Psyche, Science, and Society

Blast trauma may act at a distance

The new Science contains an important article on current thinking on traumatic brain injury (TBI) from bomb blasts:

Shell Shock Revisited: Solving the Puzzle of Blast Trauma

Even at a distance, explosions may cause lasting damage to the brain. Such findings could have big implications for arming and compensating troops

by Yudhijit Bhattacharjee

Working at the Military Hospital in Belgrade during the brutal Balkan war of the 1990s, neurologist Ibolja Cernak encountered a medical enigma. She saw soldier after soldier with memory deficits, dizziness, speech problems, and difficulties with decision-making–but no obvious injury. Cernak recalls one 19-year-old who went to a grocery store and began to weep after he couldn’t remember how to get back home. When his mother brought him to the hospital a few days later, Cernak learned what later emerged as a common element in all these cases: The soldier had survived an explosion on the battlefield.

The strange thing was that most of these patients had not suffered a direct injury to the head. And yet, in computed tomography and magnetic resonance imaging scans, Cernak saw signs of internal damage. In some cases, the brain’s ventricles–channels that carry cerebrospinal fluid– had become enlarged; and in some, there was evidence of minor bleeding.

But when Cernak dug into the medical literature for an explanation, she came up empty. According to the available research, shock waves from an explosion injure mainly air-filled organs such as the lung and the bowel, not the brain.

With a small band of collaborators in Belgrade, China, and Sweden, Cernak undertook animal studies that eventually confirmed that blast waves can cause neuronal damage. The work drew little attention until 2 years ago when hundreds of U.S. and British soldiers began returning from Iraq with symptoms similar to those of Cernak’s patients. As roadside explosions became more common, military doctors suspected that these symptoms were the likely result of mild traumatic brain injury (TBI) sustained in blasts. Seeing her observations borne out was as if “a myth had become reality,” says Cernak, who is now a researcher at the Applied Physics Laboratory at Johns Hopkins University in Baltimore, Maryland.

How blasts affect the brain has since become an urgent question in military medicine. Last summer, the U.S. Congress gave $150 million to the Department of Defense (DOD) for the first year of research on TBI– both severe injuries that damage the skull and milder ones suspected of causing neurological deficits. The Defense Advanced Research Projects Agency (DARPA) has already launched a $9 million research program aimed specifically at understanding trauma caused by shock waves, heat, and electromagnetic radiation emanating from blasts. Another $14 million a year is going to the Defense and Veterans Brain Injury Center (DVBIC), a DOD-funded agency headquartered in Washington, D.C., for research and outreach on TBI.

This flurry of interest has focused a spotlight on Cernak’s research. There is growing consensus that blasts can produce subtle injuries in the brain as suggested by Cernak several years ago. In fact, the Department of Veterans Affairs (VA) proposed a new rule this month acknowledging blast-related TBI as a special neurological condition whose symptoms may have gone undetected in the past. The proposed rule, published in the Federal Register on 3 January, would allow for greater disability compensation to victims than is granted currently.

But many researchers are skeptical of Cernak’s ideas about how these injuries might occur. Cernak postulates that blast waves ripple through the victim’s torso up into the brain through the major blood vessels, leading to neurological effects that can be slow to appear. Although she has evidence from animal experiments to back up that hypothesis, she admits that more research is needed. If the mechanism is confirmed by future studies, Cernak says, it would mean that helmets do not protect the brain against blast injury.

Besides raising questions about the protection of troops currently in combat, Cernak’s suggestion that simply being exposed to an explosion might lead to long-lasting brain damage has opened a Pandora’s box, particularly for veterans. It implies that some could be suffering from neurological deficits that went undiagnosed or were mistakenly attributed to posttraumatic stress disorder (PTSD). Indeed, since the government began putting out information about blast-related TBI, veterans have been trickling in to seek treatment for mental problems that some have lived with for decades. “It may well be that blast injuries follow the pattern of Agent Orange and Gulf War syndrome,” says former VA psychiatrist David Trudeau, referring to ill-defined health problems that have lingered for years after battle.

Hidden trauma

If Cernak had been a doctor during World War I, she says, she might well have recognized mild TBI among the thousands of soldiers who suffered from what was simply called “shell shock.” But during World War I, many doctors and military commanders viewed shell shock as a transient psychological phenomenon that affected soldiers who, in their opinion, were mentally weak.

Cernak discovered something very different: that soldiers’ mental problems seemed to be driven by enduring physical changes in the brain. To test her hypothesis, she conducted a study of 1300 patients who had suffered penetrating wounds to the lower body but not the head. More than half had suffered injuries in a blast; the rest had been wounded by projectiles. Many of the blast victims complained of symptoms such as insomnia, vertigo, and memory deficits, and more than 36% in this group showed irregular patterns of electrical activity in the brain–as measured by electroencephalograms taken within 3 days of the injury– compared to only 12% in the other group. A year later, 30% of blast- injured patients still showed abnormal brain activity compared to 4% of the rest. Cernak says the findings, published in the Journal of Trauma in 1999, suggested that the mental problems of blast victims had a biological basis.

Her study wasn’t the first to make that point. A year earlier, VA researchers had found that among veterans with PTSD, individuals with a history of blast exposure were much more likely than others to have abnormal brain activity as well as cognitive and behavioral problems.

“Our evidence pointed to the possibility that blast injury was a long- lasting injury in combat veterans,” says Trudeau, who retired in 2000. He says he was disappointed by the lack of follow-up to the study, published in the August 1998 Journal of Neuropsychiatry. “The reception we got was pretty lukewarm,” he says.

For decades, Army researchers had been studying the effects of blast waves but with a different focus. They concentrated on how to protect the lungs and bowel because the pressure from an explosion is most likely to shear at the interface of these tissues, where densities differ. DOD was so confident that advanced body armor was protecting troops against lung and bowel injuries that it closed down this research program in 2003. “We thought, why spend more money on this when we’ve fixed the problem?” says Geoffrey Ling, a neurologist and a program manager at DARPA.

Then the bad news arrived. As blast survivors from Iraq were air-lifted to hospitals, U.S. Army doctors, including Ling, who was deployed in Iraq in late 2004, began to see patients whose brains had swelled markedly within hours of being close to a blast. Some had clear head injuries but many did not. Even in cases involving visible wounds, the extent of swelling was often much greater than expected, leading neurosurgeons to wonder whether blast waves had played a role in addition to penetrating shrapnel. Ling says the patterns of vascular enlargement seen across a range of patients showed a continuum of brain injury, suggesting that there could be milder versions that were less obvious.

That suspicion has grown stronger with hundreds of soldiers returning from the war zone complaining of a common cluster of cognitive and behavioral problems. Army doctors say they have encountered many patients who are unable to perform simple addition and subtraction, read more than one sentence at a stretch, or recall simple things like what they had for lunch. “The majority are individuals who lost consciousness or were dazed after a blast but did not sustain overt head injuries,” says Ronald Riechers, a neurologist at Walter Reed Army Medical Center in Washington, D.C. “Within a short time frame, they develop headaches and notice that their reaction time and concentration are not the same as before.” Based on these evaluations, DVBIC estimates that 10% to 20% of all soldiers on duty in Iraq and Afghanistan have suffered some type of TBI.

Ling says the TBI numbers prompted DOD to restart its research on blast injury, this time with a focus on the brain. DARPA is funding two main projects as part of the first basic science effort on the topic. One will study the mechanical and cellular effects of blast waves in an animal model. Another will look at the consequences of repeated exposures to low-intensity explosions among military breachers, whose job is to blast holes into buildings using shoulder-launched weapons. “Once you know for certain what in a blast is really hurting the brain and how, you can use that to develop therapies and prevention strategies,” says Ling.

A tsunami in the brain

Although it is becoming accepted that blast waves can cause TBI, Cernak’s theory about how the damage occurs is controversial, and it has implications for how best to protect troops. She hypothesizes that when blast waves strike the body, they transfer kinetic energy and cause pressure in the main blood vessels to oscillate rapidly. A pulse travels up through the neck into the brain, damaging axonal fibers and neurons in the hippocampus, brainstem, and other structures close to cerebral vessels. The shock can also injure cells farther out in the cortical regions.

That mechanism is entirely different from the more widely studied effects of acceleration or deceleration in a car crash. Researchers know that a crash impact can shake the brain so violently that axonal fibers are torn. Some say victims of explosions could be experiencing a similar whiplashing, in contrast to Cernak’s view–which would mean that helmets designed to dampen that effect could help. “I am very skeptical that kinetic energy could be transferred through the vascular system,” says J. Clay Goodman, a neuropathologist at Baylor College of Medicine in Houston, Texas. “It is much more reasonable to consider the blast effects directly on the cranial vault and the brain.”

Cernak says her findings show the vascular route to be more plausible. In experiments that exposed rats and rabbits to a simulated blast wave in a shock tube–a cylinder through which an air pulse is transmitted at high velocity–Cernak and her colleagues found that immobilizing the animal’s head with steel plates to prevent whiplash effects did not protect against hippocampal cell damage, as they reported in the Journal of Trauma in 2001. Cernak says the vascular-transmission theory could explain the unique combination of symptoms in blast-induced TBI, as well as why neurological symptoms are seen in soldiers wearing helmets. For example, memory deficits hint at damage to the hippocampus, whereas problems in orientation reflect injuries to the cerebellum. “What’s happening in blast injury is that these inner structures are being affected,” Cernak says, in contrast to TBIs in traffic accidents and contact sports, where the cortex bears most of the brunt.

Cernak presented unpublished results last month at the Blast Injury Conference in Tampa, Florida, showing that exposure to blast waves can trigger neurodegeneration in rat brains, fragmenting the walls of neurons in the hippocampus and other regions. Similar findings have been published by Annette Saljo, a researcher at the University of Goteborg in Sweden and a collaborator of Cernak’s. Saljo and her colleagues reported in the Journal of Neurotrauma in August 2000 that rats exposed to blasts showed a buildup of neurofilament proteins in the cortex and the hippocampus during the week following the injury. This suggests that the damage can worsen over time, like a “slow cooking under the surface,” says Cernak: “One could think of it as a horribly accelerated aging of the brain.”

If blast waves indeed cause injury by vascular transmission, new types of body armor may be needed. “We would need to develop materials that completely absorb or reflect the full range of blast-wave frequencies generated by an explosion,” says Cernak, adding that current body armor only shields against some of a blast’s kinetic energy.

Cernak has done pioneering work, says John Povlishock, a neuroanatomist at Virginia Commonwealth University in Richmond, adding that she may be right that a “rapid rise and fall in venous pressure” is what stamps the blast’s signature on the brain. But more studies are needed to validate her ideas and translate the animal results into humans: “This is a topic with great economic, military, and social implications,” he says, “and as of now, the literature is extremely limited.”

Needed: A gold standard

As blast casualties from Iraq have mounted, the U.S. military has stepped up efforts to detect TBI among troops. In July 2006, the Army Surgeon General asked all unit commanders in Iraq to request TBI screening for soldiers displaying “poor marksmanship, delayed reaction times, decreased ability to concentrate, and inappropriate behavior.”
Troops who have been in a blast are evaluated by field medics using a short questionnaire that asks, among other things, if the person lost consciousness and had trouble remembering things from just before the explosion. Depending on the severity of the symptoms, they are asked to take a day off or see a neuropsychologist.

Some veterans groups believe a more aggressive screening policy is needed, especially because the symptoms of blast injury might not show up until later and because subtle injuries might not show up in standard brain scans. The ideal option, some say, would be to use a biomarker:

“We’d like to be able to do a blood test to determine the injury,” says Colonel Robert Labutta, a neurologist at the health affairs office at DOD. But until the science of blast injury is established, officials say, it does not make sense to bring home every soldier who has been in the vicinity of an explosion.

The costs of treating TBI victims from Iraq and Afghanistan could be astronomical. At last count, nearly 25,000 soldiers had been diagnosed with TBI. One estimate of the financial burden, calculated by Harvard researchers, puts the number at $14 billion over the next 20 years. But officials seem determined not to miss any cases among troops coming
home: In April, VA mandated TBI screening for all Iraq and Afghanistan veterans who come to VA hospitals for any services, even if it’s a dental exam.

The spotlight on mild TBI has drawn the attention of older combat veterans who were exposed to blasts but were never treated for neurological symptoms. Many were diagnosed with PTSD; some of the symptoms–such as depression, irritability, and attention deficit– overlap with those of mild TBI. These cases, some reaching back to the Vietnam War, could have significant legal and financial implications, says Edward Kim, a psychiatrist with Bristol-Myers Squibb in Plainsboro, New Jersey, and author of a recent report from the American Neuropsychiatric Association on the mental health effects of TBI. “I question whether DOD and the VA really want to open this can of worms,”
he says. For example, a veteran with Alzheimer’s disease could make a claim pointing to research showing that TBI increases the risk of developing Alzheimer’s disease.

Cernak says she has been receiving e-mails and phone calls from veterans thanking her for her research and seeking more information. Last month, she got a call from a 47-year-old woman who had served in the first Gulf War. The woman had been a teacher before she went to the combat zone, where she was exposed to repeated blasts. After she returned home, she had to stop teaching because she could not remember any facts. The story reminded Cernak why she had begun studying this obscure field 2 decades ago. “Soldiers anywhere are one of the most vulnerable populations in the world,” she says. “It is a moral obligation to help them.”

2 comments January 25th, 2008

Are teen sex and delinquenct linked?

The Washington Post has an article partially on a study claiming to debunk the finding that early teen consensual sex leads to later delinquency. By comparing pairs of twins, they suggest that the effect might even be in the opposite direction. While hardly definitive, it looks like a nice attempt to use sophisticated data analysis along with careful conceptual analysis to clarify important social issues.

The article also discusses other issues,including a claim that the relationship between IQ and breastfeeding, about which I blogged last week, may be artifactual:

A recent study by Scottish researchers asked whether the higher IQs seen in breast-fed children are the result of the breast milk they got or some other factor. By comparing the IQs of sibling pairs in which one was breast-fed and the other not, it found that breast milk is irrelevant to IQ and that the mother’s IQ explains both the decision to breast-feed and her children’s IQ.

I suspect neither of these studies is the last word on the breastfeeding-IQ link.

Another issue involves the benefits and risks of early parenting by poor black girls. For decades, Arline Geronimus has made the case that poor young girls are often better off having children young, in direct contradiction of our society’s obsession with preventing teen pregnancy. I was in a seminar with Arlene during our postdocs in 1986-87 and remember her making a quite plausible case. She apparently has continued to amass evidence over the 20 years since.

While none of these studies are definitive, they all emphasize the importance of careful research work before developing social interventions to address what, in some instances, are nonexistent problems.

Here’s the entire article:

Study Debunks Theory On Teen Sex, Delinquency
New Analyses Challenging Many Old Assumptions

By Rick Weiss

Researchers at Ohio State University garnered little attention in February when they found that youngsters who lose their virginity earlier than their peers are more likely to become juvenile delinquents. So obvious and well established was the contribution of early sex to later delinquency that the idea was already part of the required curriculum for federal “abstinence only” programs.

There was just one problem: It is probably not true. Other things being equal, a more probing study has found, youngsters who have consensual sex in their early-teen or even preteen years are, if anything, less likely to engage in delinquent behavior later on.

That new analysis, a reworking of the same data the Ohio team used, is one of several recent instances in which a more precise parsing of data has begun to turn long-standing societal presumptions on their head. By bringing evidence to bear on complex social issues, these studies are forcing individuals and policymakers to rethink such hot-button topics as the benefits of breast-feeding, the risks of teen child-bearing and, in the latest example, the harms long presumed to result from teen sex.

Like many of the newer studies, the latest one — led by Paige Harden, a doctoral candidate in psychology at the University of Virginia in Charlottesville — used the powerful techniques of behavioral genetics. The field specializes in studies on twins, research that can help tell whether behavioral traits are the result of genes or the social environment, and that has periodically stirred controversy when it has focused on the genetic underpinnings of criminality and intelligence.

But the specialty’s analytic methods can also help tell whether one behavior, such as early sex, is merely correlated with or actually causes a second behavior that is often found with it, such as delinquency. If two behaviors often exist in the same people but are found not to be connected by cause and effect, then a third factor is likely to be causing both.

That kind of finding can help identify better targets for prevention efforts, experts say.

“Behavioral geneticists have long sought to establish causal links between genes and complex behaviors. So it’s fascinating to see them use the tools of their trade to dispute widely held beliefs” about the social roots of some of those behaviors, said Erik Parens, a senior research scholar who has tracked the field intensively at the Hastings Center, a Garrison, N.Y., science and ethics think tank.

The latest example started when Dana Haynie, a sociologist at Ohio State, and her then-graduate student, Stacy Armour, published a study in February in the Journal of Youth and Adolescence. They analyzed data collected from more than 7,000 children as part of the National Longitudinal Study of Adolescent Health, a federally funded survey that in 1994 began gathering information about the health-related behavior of U.S. schoolchildren who were then in grades seven through 12.

Haynie and Armour divided the children into three groups based on when they first had sex: when they were younger, about the same age or older than the age at which most of their local peers lost their virginity. (It varies by region, but on average, U.S. children lose their virginity at age 16.) They also compiled information on graffiti-painting, shoplifting, drug-selling and other “problem behaviors” by those young people in later years.

Their conclusion: One year after losing their virginity, children in the early category were 20 percent more likely than those who started having sex at the average age to engage in delinquent behavior, even when several other relevant factors such as wealth, race, parental involvement and physical development were taken into account.

Those findings supported the widely held notion that loss of virginity at a relatively young age appears to, as Haynie and Armour wrote, “open the doorway to problem behaviors.”

Harden, at the University of Virginia, didn’t believe it.

Looked at from a similarly high altitude, she said, people might conclude that red meat is a health food, since people live longer in countries where more is eaten. Only when the issue is studied within one country does red meat’s link to chronic diseases appear.

Suspecting such an error in the Haynie study, Harden and three colleagues, including her adviser, Eric Turkheimer, an expert in behavioral genetics, studied more than 500 pairs of twins in the same national survey analyzed by the Ohio team. Because twin pairs share similar or identical genetic inheritances (depending on whether they are fraternal or identical) and the same home environment, twin studies are useful for seeing through false cause-and-effect relationships.

The team looked at identical twin pairs in which one twin initiated sex younger than the other, then team members tallied subsequent problem behaviors. If sex really adds to the chances of delinquency, then early-sex teens should end up delinquent more often than their later-sex twins.

“It turns out that there was no positive relationship between age of first sex and delinquency,” Harden said.

The way to reconcile that with the previous evidence of a link is to conclude that some other factors are promoting both early sex and delinquency, she said. In an e-mail, Haynie agreed. And the Virginia study, to appear in the March 2008 issue of the Journal of Youth and Adolescence, offers some clues.

It found that identical twins, who have the same DNA, were more similar to one another in the ages at which they lost their virginity than were fraternal twins, whose DNA patterns are 50 percent the same — an indication that genes influence the age at which a person will first have sex. Other twin studies have found the same pattern for delinquency.

Together, those findings suggest that some genes — perhaps, for example, those that increase impulsivity and risk-taking — may underlie both behaviors.

“You need to have some appetite for risk-taking to be a delinquent. And the same if you’re 13 and going to have sex for the first time,” Harden said.

Efforts to prevent delinquency can hardly take aim at people’s genes. But the Virginia study also indicates that social factors, as yet unidentified but perhaps involving relationships with family and friends, have an even bigger impact than genes on whether a child will become delinquent. Those are the things that should be identified and targeted by delinquency-prevention programs, said Jeanne Brooks-Gunn, co-director of Columbia University’s National Center for Children and Families.

“I wouldn’t be focusing on early sexuality . . . to alter rates of delinquency,” she said.

Perhaps most surprising, the Virginia study found that adolescents who had sex at younger ages were less likely to end up delinquent than those who lost their virginity later. Many factors play into a person’s readiness for sex, but in at least some cases sexual relationships may offer an alternative to trouble, the researchers say.

Even then, there are emotional and physical risks. Young adolescents, in particular, are less likely to use condoms and so are vulnerable to sexually transmitted diseases and unwanted pregnancies.

But those are risks that other nations have mitigated with education, Harden and Turkheimer said, while U.S. educators wanting a piece of the nation’s $200 million “abstinence only” budget must adhere to a curriculum that links sex to delinquency and explicitly precludes discussion of contraception.

The new study “really calls into question the usefulness of abstinence education for preventing behavior problems,” Harden said, “and questions the bigger underlying assumption that all adolescent sex is always bad.”

Similar re-analyses have begun to undermine other conventional notions about health.

A recent study by Scottish researchers asked whether the higher IQs seen in breast-fed children are the result of the breast milk they got or some other factor. By comparing the IQs of sibling pairs in which one was breast-fed and the other not, it found that breast milk is irrelevant to IQ and that the mother’s IQ explains both the decision to breast-feed and her children’s IQ.

In another example, Arline Geronimus, a University of Michigan professor of health behavior who is now a fellow at Stanford University’s Center for Advanced Study, knew that babies born to teenagers are more likely to die in their first year of life than those born to older women.

“But that is an apples-to-oranges comparison,” she said. In New York City, for example, far more teen mothers live in Harlem than on the Upper East Side, she said, and “there are a lot of differences between those groups.”

So Geronimus looked more closely and got a different answer.

“If you compare Harlem teen moms to Harlem older moms, you find that the kids of the teen moms are actually less likely to die,” she said. The reasons include the fact that, unlike older women, poor teenagers are generally not juggling jobs and have older relatives to help.

It can make sense for poor women to have children when they are quite young, Geronimus concludes, and any effort to change that ought to treat it as an economic problem, not a health education problem.

In a different re-analysis, Geronimus made another counterintuitive finding. While it is true that, in general, teen mothers are less likely to breast-feed their babies than older moms, it is not true among poor women. Poor teenagers are actually more likely to breast-feed than poor older moms, in large part because the older women have jobs that don’t grant them the time to breast-feed or pump milk.

Because of that misconception, programs promoting breast-feeding have targeted teens instead of older women, Geronimus said. And they have taken aim, in part, at a concern that teenagers were believed to have: the cosmetic effects of breast-feeding on their breasts.

“So you’ve targeted the wrong population,” Geronimus said, “and come up with the wrong kind of intervention.”

1 comment November 11th, 2007

Breastfeeding: Nature determines nurture influence

According to the BBC, a new study reports finding a gene that determines whether breastfeeding will increase a baby’s IQ. The 90% of babies (the article doesn’t say in what population) with the gene will gain an average of 7 IQ points if breastfed, the other 10% will not experience gain. This study is one of a number showing that traditional models of the nature-nurture relationship, in which the two are additive effects, are flawed. Rather, their is an interaction between them. But elucidating the nature of the interaction requires identification of mechanisms, in this case the FADS2 gene. Perhaps gradually the “nature-nurture” dichotomy will die out as we learn more about how these factors interact in development:

Gene ‘links breastfeeding to IQ’
A single gene influences whether breastfeeding improves a child’s intelligence, say London researchers.

Children with one version of the FADS2 gene scored seven points higher in IQ tests if they were breastfed.

But the Proceedings of the National Academy of Sciences study found breastfeeding had no effect on the IQ of children with a different version.

The gene in question helps break down fatty acids from the diet, which have been linked with brain development.

Seven points difference is enough to put the child in the top third of the class, the researchers said.

Some 90% of people carry the version of the gene which was associated with better IQ scores in breastfed children.

Researchers at the Institute of Psychiatry, Kings College London, used data from two previous studies of breast-fed infants in Britain and New Zealand, which involved more than 3,000 children.

IQ was measured at various points between the ages of five and 13 years in the studies.

Previous studies on intelligence and breastfeeding have come up with conflicting results.

There has been some debate as to whether mothers who had more education or who were from more affluent backgrounds were more likely to breastfeed, skewing the results.

Nature versus nurture

Professor Terrie Moffitt, a co-author on the paper, said the findings gave a fresh perspective on the arguments by showing a physiological mechanism that could account for the difference between breastfed and bottle-fed babies.

“The argument about intelligence has been about nature versus nurture for at least a century,” she said.

“However, we have shown that in fact nature works via nurture to create better health outcomes.”

Since the studies used in the analysis were done, manufacturers have begun to add fatty acids to formula milk but there have been inconsistent results on the benefits.

Belinda Phipps, of the National Childbirth Trust, said: “This shows for the majority of parents they can have a positive effect on their babies IQ by breastfeeding.”

Catherine Collins, a dietician at St Georges Hospital in London and spokesperson for the British Dietetic Association, said the study highlighted the interaction between nutrition and genetics.

“In this study you have an effect that suggests that nature is more important that nurture.

“If nine out of 10 babies benefit, then that is a very good chance.”

But she added the study did not specify how long babies were breastfed for and it may be that even breastfeeding for a short period may be beneficial for intelligence.

Professor Jean Golding, who founded the ALSPAC study set up in the 1990s to follow the development of thousands of children in the South West of England, said the results were fascinating and they would be doing a further study of the gene.

“In the past people have had different results about whether breastfeeding improves IQ and this would sort out the reason why,” she said.

1 comment November 6th, 2007

Study finds liberal-conservative difference in brain functioning

The Los Angeles Times reports on a new study finding differences in brain function between liberals and conservatives. Using a classic experimental paradigm, they found that liberals were more open to new information, whereas conservatives were more likely to block potentially distracting information:

Study finds left-wing brain, right-wing brain

Even in humdrum nonpolitical decisions, liberals and conservatives literally think differently, researchers show.

By Denise Gellene, Los Angeles Times Staff Writer

Exploring the neurobiology of politics, scientists have found that liberals tolerate ambiguity and conflict better than conservatives because of how their brains work.

In a simple experiment reported today in the journal Nature Neuroscience, scientists at New York University and UCLA show that political orientation is related to differences in how the brain processes information.

Previous psychological studies have found that conservatives tend to be more structured and persistent in their judgments whereas liberals are more open to new experiences. The latest study found those traits are not confined to political situations but also influence everyday decisions.

The results show “there are two cognitive styles — a liberal style and a conservative style,” said UCLA neurologist Dr. Marco Iacoboni, who was not connected to the latest research.

Participants were college students whose politics ranged from “very liberal” to “very conservative.” They were instructed to tap a keyboard when an M appeared on a computer monitor and to refrain from tapping when they saw a W.

M appeared four times more frequently than W, conditioning participants to press a key in knee-jerk fashion whenever they saw a letter.

Each participant was wired to an electroencephalograph that recorded activity in the anterior cingulate cortex, the part of the brain that detects conflicts between a habitual tendency (pressing a key) and a more appropriate response (not pressing the key). Liberals had more brain activity and made fewer mistakes than conservatives when they saw a W, researchers said. Liberals and conservatives were equally accurate in recognizing M.

Researchers got the same results when they repeated the experiment in reverse, asking another set of participants to tap when a W appeared.

Frank J. Sulloway, a researcher at UC Berkeley’s Institute of Personality and Social Research who was not connected to the study, said the results “provided an elegant demonstration that individual differences on a conservative-liberal dimension are strongly related to brain activity.”

Analyzing the data, Sulloway said liberals were 4.9 times as likely as conservatives to show activity in the brain circuits that deal with conflicts, and 2.2 times as likely to score in the top half of the distribution for accuracy.

Sulloway said the results could explain why President Bush demonstrated a single-minded commitment to the Iraq war and why some people perceived Sen. John F. Kerry, the liberal Massachusetts Democrat who opposed Bush in the 2004 presidential race, as a “flip-flopper” for changing his mind about the conflict.

Based on the results, he said, liberals could be expected to more readily accept new social, scientific or religious ideas.

“There is ample data from the history of science showing that social and political liberals indeed do tend to support major revolutions in science,” said Sulloway, who has written about the history of science and has studied behavioral differences between conservatives and liberals.

Lead author David Amodio, an assistant professor of psychology at New York University, cautioned that the study looked at a narrow range of human behavior and that it would be a mistake to conclude that one political orientation was better. The tendency of conservatives to block distracting information could be a good thing depending on the situation, he said.

Political orientation, he noted, occurs along a spectrum, and positions on specific issues, such as taxes, are influenced by many factors, including education and wealth. Some liberals oppose higher taxes and some conservatives favor abortion rights.

Still, he acknowledged that a meeting of the minds between conservatives and liberals looked difficult given the study results.

“Does this mean liberals and conservatives are never going to agree?” Amodio asked. “Maybe it suggests one reason why they tend not to get along.”

Of course, this study does not, by itself, provide evidence on causality. It is possible that experience in considering alternative explanations may develop the brain regions dealing with new information.

4 comments September 10th, 2007

Lead poinsoning and crime rates: The case for public health as public safety

This is a topic about which I have no special competence. But, like other social researchers and citizens, I have been puzzled by the dropping crime rate. Many theories have been proposed, but none has seemed to really explain the phenomenon. Now the Washington Post brings news of a little-know theory with, evidently, strong empirical support: crime rate reflects the lead poisoning rate 20 years earlier:

Research Links Lead Exposure, Criminal Activity
Data May Undermine Giuliani’s Claims

By Shankar Vedantam
Sunday, July 8, 2007

Rudy Giuliani never misses an opportunity to remind people about his track record in fighting crime as mayor of New York City from 1994 to 2001.

“I began with the city that was the crime capital of America,” Giuliani, now a candidate for president, recently told Fox’s Chris Wallace. “When I left, it was the safest large city in America. I reduced homicides by 67 percent. I reduced overall crime by 57 percent.”

Although crime did fall dramatically in New York during Giuliani’s tenure, a broad range of scientific research has emerged in recent years to show that the mayor deserves only a fraction of the credit that he claims. The most compelling information has come from an economist in Fairfax who has argued in a series of little-noticed papers that the “New York miracle” was caused by local and federal efforts decades earlier to reduce lead poisoning.

The theory offered by the economist, Rick Nevin, is that lead poisoning accounts for much of the variation in violent crime in the United States. It offers a unifying new neurochemical theory for fluctuations in the crime rate, and it is based on studies linking children’s exposure to lead with violent behavior later in their lives.

What makes Nevin’s work persuasive is that he has shown an identical, decades-long association between lead poisoning and crime rates in nine countries.

“It is stunning how strong the association is,” Nevin said in an interview. “Sixty-five to ninety percent or more of the substantial variation in violent crime in all these countries was explained by lead.”

Through much of the 20th century, lead in U.S. paint and gasoline fumes poisoned toddlers as they put contaminated hands in their mouths. The consequences on crime, Nevin found, occurred when poisoning victims became adolescents. Nevin does not say that lead is the only factor behind crime, but he says it is the biggest factor.

Giuliani’s presidential campaign declined to address Nevin’s contention that the mayor merely was at the right place at the right time. But William Bratton, who served as Giuliani’s police commissioner and who initiated many of the policing techniques credited with reducing the crime rate, dismissed Nevin’s theory as absurd. Bratton and Giuliani instituted harsh measures against quality-of-life offenses, based on the “broken windows” theory of addressing minor offenses to head off more serious crimes.

Many other theories have emerged to try to explain the crime decline. In the 2005 book “Freakonomics,” Steven D. Levitt and Stephen J. Dubner said the legalization of abortion in 1973 had eliminated “unwanted babies” who would have become violent criminals. Other experts credited lengthy prison terms for violent offenders, or demographic changes, socioeconomic factors, and the fall of drug epidemics. New theories have emerged as crime rates have inched up in recent years.

Most of the theories have been long on intuition and short on evidence. Nevin says his data not only explain the decline in crime in the 1990s, but the rise in crime in the 1980s and other fluctuations going back a century. His data from multiple countries, which have different abortion rates, police strategies, demographics and economic conditions, indicate that lead is the only explanation that can account for international trends.

Because the countries phased out lead at different points, they provide a rigorous test: In each instance, the violent crime rate tracks lead poisoning levels two decades earlier.

“It is startling how much mileage has been given to the theory that abortion in the early 1970s was responsible for the decline in crime” in the 1990s, Nevin said. “But they legalized abortion in Britain, and the violent crime in Britain soared in the 1990s. The difference is our gasoline lead levels peaked in the early ’70s and started falling in the late ’70s, and fell very sharply through the early 1980s and was virtually eliminated by 1986 or ‘87.

“In Britain and most of Europe, they did not have meaningful constraints [on leaded gasoline] until the mid-1980s and even early 1990s,” he said. “This is the reason you are seeing the crime rate soar in Mexico and Latin America, but [it] has fallen in the United States.”

Lead levels plummeted in New York in the early 1970s, driven by federal policies to eliminate lead from gasoline and local policies to reduce lead emissions from municipal incinerators. Between 1970 and 1974, the number of New York children heavily poisoned by lead fell by more than 80 percent, according to data from the New York City Department of Health.

Lead levels in New York have continued to fall. One analysis in the late 1990s found that children in New York had lower lead exposure than children in many other big U.S. cities, possibly because of a 1960 policy to replace old windows. That policy, meant to reduce deaths from falls, had an unforeseen benefit — old windows are a source of lead poisoning, said Dave Jacobs of the National Center for Healthy Housing, an advocacy group that is publicizing Nevin’s work. Nevin’s research was not funded by the group.

The later drop in violent crime was dramatic. In 1990, 31 New Yorkers out of every 100,000 were murdered. In 2004, the rate was 7 per 100,000 — lower than in most big cities. The lead theory also may explain why crime fell broadly across the United States in the 1990s, not just in New York.

The centerpiece of Nevin’s research is an analysis of crime rates and lead poisoning levels across a century. The United States has had two spikes of lead poisoning: one at the turn of the 20th century, linked to lead in household paint, and one after World War II, when the use of leaded gasoline increased sharply. Both times, the violent crime rate went up and down in concert, with the violent crime peaks coming two decades after the lead poisoning peaks.

Other evidence has accumulated in recent years that lead is a neurotoxin that causes impulsivity and aggression, but these studies have also drawn little attention. In 2001, sociologist Paul B. Stretesky and criminologist Michael Lynch showed that U.S. counties with high lead levels had four times the murder rate of counties with low lead levels, after controlling for multiple environmental and socioeconomic factors.

In 2002, Herbert Needleman, a psychiatrist at the University of Pittsburgh, compared lead levels of 194 adolescents arrested in Pittsburgh with lead levels of 146 high school adolescents: The arrested youths had lead levels that were four times higher.

“Impulsivity means you ignore the consequences of what you do,” said Needleman, one of the country’s foremost experts on lead poisoning, explaining why Nevin’s theory is plausible. Lead decreases the ability to tell yourself, “If I do this, I will go to jail.”

Nevin’s work has been published mainly in the peer-reviewed journal Environmental Research. Within the field of neurotoxicology, Nevin’s findings are unsurprising, said Ellen Silbergeld, professor of environmental health sciences at Johns Hopkins University and the editor of Environmental Research.

“There is a strong literature on lead and sociopathic behavior among adolescents and young adults with a previous history of lead exposure,” she said.

Two new studies by criminologists Richard Rosenfeld and Steven F. Messner have looked at Giuliani’s policing policies. They found that the mayor’s zero-tolerance approach to crime was responsible for 10 percent, maybe 20 percent, at most, of the decline in violent crime in New York City.

Nevin acknowledges that crime rates are rising in some parts of the United States after years of decline, but he points out that crime is falling in other places and is still low overall by historical measures. Also, the biggest reductions in lead poisoning took place by the mid-1980s, which may explain why reductions in crime might have tapered off by 2005. Lastly, he argues that older, recidivist offenders — who were exposed to lead as toddlers three or four decades ago — are increasingly accounting for much of the violent crime.

Nevin’s finding may even account for phenomena he did not set out to address. His theory addresses why rates of violent crime among black adolescents from inner-city neighborhoods have declined faster than the overall crime rate — lead amelioration programs had the biggest impact on the urban poor. Children in inner-city neighborhoods were the ones most likely to be poisoned by lead, because they were more likely to live in substandard housing that had lead paint and because public housing projects were often situated near highways.

Chicago’s Robert Taylor Homes, for example, were built over the Dan Ryan Expressway, with 150,000 cars going by each day. Eighteen years after the project opened in 1962, one study found that its residents were 22 times more likely to be murderers than people living elsewhere in Chicago.

Nevin’s finding implies a double tragedy for America’s inner cities: Thousands of children in these neighborhoods were poisoned by lead in the first three quarters of the last century. Large numbers of them then became the targets, in the last quarter, of Giuliani-style law enforcement policies.

Add comment July 9th, 2007

Men talk as much as women

Men talk less than women. This has become a common piece of folklore. Women utter almost three times as many words as men do, several textbooks tell us. A new study actually counts the words uttered by college men and women and finds a trivial, not statistically significant, difference. Time reports on the study, published in Science [subscribers only]:

Study: Women Don’t Talk More Than Guys
Thursday, Jul. 05, 2007
By AP/RANDOLPH E. SCHMID

Another stereotype — chatty gals and taciturn guys — bites the dust. Turns out, when you actually count the words, there isn’t much difference between the sexes when it comes to talking.

A team led by Matthias R. Mehl, an assistant professor of psychology at the University of Arizona, came up with the finding, which is published in Friday’s issue of the journal Science. The researchers placed microphones on 396 college students for periods ranging from two to 10 days, sampled their conversations and calculated how many words they used in the course of a day.

The score: Women, 16,215. Men, 15,669.

The difference: 546 words: “Not statistically significant,” say the researchers.

“What’s a 500-word difference, compared with the 45,000-word difference between the most and the least talkative persons” in the study, said Mehl.

Co-author James W. Pennebaker, chairman of the psychology department at the University of Texas, said the researchers collected the recordings as part of a larger project to understand how people are affected when they talk about emotional experiences. They were surprised when a magazine article asserted that women use an average of 20,000 words per day compared with 7,000 for men. If there had been that big a difference, he thought, they should have noticed it.

They found that the 20,000-7,000 figures have been used in popular books and magazines for years. But they couldn’t find any research supporting them. “Although many people believe the stereotypes of females as talkative and males as reticent, there is no large-scale study that systematically has recorded the natural conversations of large groups of people for extended periods of time,” Pennebaker said.

Indeed, Mehl said, one study they found, done in workplaces, showed men talking more. Still, the idea that women use nearly three times as many words a day as men has taken on the status of an “urban legend,” he said. “We realized we had the data,” Mehl said in a telephone interview, so they went back to their recordings and calculated the actual numbers.

Their research began with one group of students in 1998, two groups sampled in 2001, two in 2003 and a final group in 2004. One of the 2003 groups involved 51 students in Mexico, the rest were all in the United States. The students were fitted with unobtrusive recorders that sampled their conversations — the students didn’t know when the recorders were on. From the samples, a total number of words for the day could be calculated.

Of the six groups sampled, women used more words than men in three and men used more words than women in the other three, including the one in Mexico. The research was limited to college students, but Pennebaker said he believes it would probably apply to others in the same age range. “The question is, how it applies to people as we get older,” he said in a telephone interview on Thursday. Mehl said he thinks it should apply across age groups, but he wondered how it would be affected by different cultures.

Add comment July 5th, 2007

Doctors telling personal anecdotes to patients aren’t doing the patients a favor

As a long-time researcher and proselytizer among my clinical colleagues for the value of research, I love examples where researchers start out with an hypothesis only to be told by the data that they were wrong. Yesterday’s New York Times provides one of these examples.

Those concerned with improving doctor patient interaction have encouraged doctors to loosen up how they talk to patients, in order to build a relationship that can facilitate communication and compliance with medical advice. Some thought that doctors being willing to reveal personal details about themselves might contribute to improved communication.

Researchers studied doctors in Rochester who agreed to have two unidentified pseudo patients come to their office and surreptitiously record the consultation. the researchers were surprised by the results. When the doctors revealed personal details, rather than aid communication, it seemed to hijack the discussion to the doctor’s concerns and away from the patient’s.

June 26, 2007

Study Says Chatty Doctors Forget Patients

by Gina Kolata

A new patient comes into a doctor’s office weighing 204 pounds. He’s six feet tall. The following conversation ensues:

Doctor: Is that up a little bit for you, weightwise?

Patient: It might be up a few pounds. I used to jog and I just haven’t …

Doctor: See, ’cause I’m weighing more like 172, 173 and I’m six foot. And I’m still running. I’m doing the 5 and 10 and 15 K’s. The half marathons and …

Patient: So, I’m 30 pounds heavier than you?

Doctor: Right now, yeah.

That, a group of researchers say, is part of an actual conversation they recorded in the course of a study that showed that many doctors waste patients’ time and lose their focus in office visits by interjecting irrelevant information about themselves.

Their paper, published yesterday in The Archives of Internal Medicine, involved 100 primary-care doctors in the Rochester area. As part of a study on patient care and outcomes, the doctors agreed to allow two people trained to act as patients come to their offices sometime over the course of a year. The test patients would surreptitiously make an audio recording of the encounter. The investigators analyzed recordings of 113 of those office visits, excluding situations when the doctors figured out that the patient was fake.

To their surprise, the researchers discovered that doctors talked about themselves in a third of the audio recordings and that there was no evidence that any of the doctors’ disclosures about themselves helped patients or established rapport.

Nor, in the vast majority of cases, did the doctors circle back to the personal conversation or try to build upon it.

“I think all of us on the team thought self-disclosure is a potentially positive aspect to building a doctor-patient relationship and that we ourselves were quite good at it,” said Susan H. McDaniel, a psychologist who is associate chairwoman of the department of family medicine at the University of Rochester and lead author of the study.

“We were quite shocked,” Dr. McDaniel added. “We realized that maybe not 100 percent of the time, but most of the time self-disclosure had more to do with us than with the patients.”

Dr. Howard B. Beckman, medical director of the Rochester Individual Practice Association and an internist and geriatrician who was an author of the study, analyzed conversations before and after the doctors started talking about themselves.

“I’d been saying for many years that disclosure was a form of patient support,” Dr. Beckman said. “If someone says, ‘I have a problem,’ and you say, ‘I understand because I have it, too,’ that would be comforting.” But, he added, “in truth that never happens.”

Patients were not comforted, he said, and conversations got off track. Four out of five times when a doctor interjected personal information, the doctor never returned to the topic under discussion before the interruption.

“We found that the longer the disclosures went on, the less functional they were,” Dr. Beckman said. “Then the patient ends up having to take care of the doctor and then the question is who should be paying whom.”

The researchers studied the conversations looking for any hint that patients were helped when the doctors talked about themselves.

“We looked for any statement of comfort, any statement of appreciation, any deepening of the conversation,” Dr. Beckman said.

They found none.

Dr. Jeffrey Borkan, who is a professor and chairman of the department of family medicine at Brown University, said it was easy to see why doctors thought it was helpful to talk about themselves. Doctors are told that they must make a connection with patients. But, Dr. Borkan said, “the instruction is often imprecise — how do you make a connection?” Many think the way to do it is by talking about themselves.

“What’s shocking about this article is how often they moved from the patient’s concerns to their own,” Dr. Borkan said.

But Dr. Richard Frankel, a professor of medicine and geriatrics at Indiana University, hopes that doctors do not conclude that the best course is to clam up completely about themselves.

Patients, for example, may ask a female physician who is pregnant when she is due or whether she is having a boy or a girl. “It would not be appropriate not to say anything,” Dr. Frankel said.

The Rochester researchers, though, say their results opened their eyes to their own transgressions and made them change their ways.

They also made them see that they, too, had been the victims of doctors’ time-wasting disclosures.

Dr. McDaniel said, “I went to my doctor recently, and I realized after I left, when I was in the parking lot, that I had only asked one of my two questions because my doctor was telling me about his trip to Italy.”

But not all doctors informed of the results saw themselves in the data.

Dr. John K. Min, an internist at the Kernodle Clinic in Burlington, N.C., said he had always been circumspect when he talked to patients.

Then, however, he recalled a patient who came to see him five years ago for a physical exam. Dr. Min is avid about building furniture and the patient was skilled at furniture building. The patient spent 40 minutes with Dr. Min. When he left, Dr. Min looked at his notes.

“I realized that I didn’t even examine him,” Dr. Min said. The man, he added, was gracious when Dr. Min called to apologize.

“He said, ‘We’ll just wait for next time,’ ” Dr. Min recalled.

This study has potential relevance for psychotherapy as well. In the therapy world, as in medicine, there has been discussion of whether therapist self-disclosure might facilitate an improved therapist-patient relationship and increased patient sel-disclosure. This study would suggest that examination of this possibility should carefully distinguish between cases where the therapist makes brief personal comments in an attempt to further patient talk and cases where the therapists ends up hijacking the conversation.

2 comments June 27th, 2007

Newstudy: Ritalin use doubles after divorce

A very interesting study. Unusually, the reporter accurately conveys the complexity of interpreting non-experimental data. The study suggests that divorce may be an important life stressor leading to increased symptomatology in kids. But there are several other plausible explanations. Yet another explanation not described here is the possibility that custodial parents (usually mothers) are more stressed after divorce and are less able to tolerate certain behaviors in their child:

Ritalin use doubles after divorce, study finds

By Scott Anderson Tue Jun 5, 9:47 AM ET

TORONTO (Reuters) - Children from broken marriages are twice as likely to be prescribed attention-deficit drugs as children whose parents stay together, a Canadian researcher said on Monday, and she said the reasons should be investigated.

More than 6 percent of 633 children from divorced families were prescribed Ritalin, compared with 3.3 percent of children whose parents stayed together, University of Alberta professor Lisa Strohschein reported in the Canadian Medical Association Journal.

The study of more than 4,700 children started in 1994, while all the families were intact, Strohschein said. They followed the children’s progress to see what happened to their families and to see what drugs were prescribed.

“It shows clearly that divorce is a risk factor for kids to be prescribed Ritalin,” Strohschein said.

Other studies have shown that children of single parents are more likely to get prescribed drugs such as Ritalin. But is the problem caused by being born to a never-married mother, or some other factor?

“So the question was, ‘is it possible that divorce acts a stressful life event that creates adjustment problems for children, which might increase acting out behavior, leading to a prescription for Ritalin?”‘ Strohschein said in a statement.

“On the other hand, there is also the very public perception that divorce is always bad for kids and so when children of divorce come to the attention of the health-care system — possibly because parents anticipate their child must be going through adjustment problems — doctors may be more likely to diagnose a problem and prescribe Ritalin.”

Ritalin, known generically as methylphenidate, is a psychostimulant drug most commonly prescribed for the treatment of attention-deficit hyperactivity disorder in children.

There is a big debate in much of the developed world over whether it may be over-prescribed — given to children who do not really need it. In March, a University of California, Berkeley study found that the use of drugs to treat ADHD has more than tripled worldwide since 1993.

Strohschein said it is possible that some mental health problems pre-date the divorce, so “it is possible that these kids had these problems before, but are only being identified afterward.”

Her study was not designed to find out why the children were prescribed the drug.

“I might be finished with the survey, but I am not necessarily finished with the question,” she said in a telephone interview.

Add comment June 6th, 2007

Air Force psychological operations interested in neurobiology of dread (anticipation of pain)

A study last year on the neurobiology of dread gives an idea of what our military Psychological Operations folks are paying attention to. A link on this Air Force Psychological Operations web site is to this article on a recent study on the neurobiology of dread: The Real Pain of Dread with this intrguing subtitle: According to brain-imaging studies, the anticipation of pain can be just as agonizing as the experience of it.

While this research appears to be benign in intention, having been funded by the National Institute on Drug Abuse, it sure is interesting that it is one of a very few research papers cited by the Air Force PSYOPS folks. After all, creating an anticipation of pain is a central element in the United States” psychological torture paradigm.

It also makes one wonder what the calls for increased neurobiological research into interrogation strategies may actually be about.

1 comment May 14th, 2007

Alfred McCoy lectures on psychological torture

On March 19, 2007, Survivors International in San Francisco sponsored a lecture by Alfred McCoy on the American development of psychological torture. It was filmed and can be watched here. Unfortunately, American Psychological Association Ethics Director Stephen Behnke has not so far given permission for SI to use his discussion material.

1 comment April 23rd, 2007