Head impacts lead to lower test scores

A new study shows that non-concussion head impacts can result in lower test scores and brain changes over time.

Repeated blows to the head during a season of contact sports may cause changes in the brain's white matter and affect cognitive abilities even if none of the impacts resulted in a concussion, according to a study published today in the journalNeurology.

Using a form of magnetic resonance imaging, or MRI, researchers at the Indiana University School of Medicine and the Geisel School of Medicine at Dartmouth College found significant differences in brain white matter of varsity football and hockey players compared with a group of noncontact-sport athletes following one season of competition. White matter is composed primarily of axons, the long fibers that transmit signals between neurons.

"The contact sports and noncontact-sports groups differed, and the number of times the contact sports participants were hit, and the magnitude of the hits they sustained, were correlated with changes in the white matter measures," said Thomas W. McAllister, M.D., chair of the IU Department of Psychiatry.

"In addition, there was a group of contact sports athletes who didn't do as well as predicted on tests of learning and memory at the end of the season, and we found that the amount of change in the white matter measures was greater in this group," Dr. McAllister said.

The study was conducted while Dr. McAllister was Millennium Professor of Psychiatry at Dartmouth.

"This study raises the question of whether we should look not only at concussions but also the number of times athletes receive blows to the head and the magnitude of those blows, whether or not they are diagnosed with a concussion," Dr. McAllister said.

Two groups of Dartmouth athletes were studied: 80 football and ice hockey players in the contact sports group, and 79 athletes drawn from such noncontact sports as track, crew and Nordic skiing. The football and hockey players wore helmets equipped with accelerometers, which enabled the researchers to compile the number and severity of impacts to their heads. Players who sustained a concussion during the season were not included in the analysis.

The athletes were administered a form of MRI test known as diffusion tensor imaging, which is used to measure the integrity of the white matter. They were also given the California Verbal Learning Test II, a measure of verbal learning and memory.

The study did not find "large-scale, systematic differences" in the brain scan measures at the end of the season, which the authors found "somewhat reassuring" and consistent with the fact that thousands of individuals have played contact sports for many years without developing progressive neurodegenerative disorders.

However, the results do suggest that some athletes may be more susceptible to repeated head impacts that do not involve concussions, although much more research would be necessary to determine how to identify those athletes.

More work would also be necessary to determine whether the effects of the head impacts are long-lasting or permanent, and whether they are cumulative.

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Poverty in children and brain development - A Neuro-Thanksgiving Consideration

A Neuro-Thanksgiving Consideration

This study looks at a link between poverty during early childhood and impaired brain development. JR


Poverty in early childhood appears to be associated with smaller brain volumes measured through imaging at school age and early adolescence, according to a study published byJAMA Pediatrics, a JAMA Network publication.

Poverty is known to be associated with a higher risk of poor cognitive outcomes and school performance, according to the study background.

Joan Luby, M.D., of the Washington University School of Medicine, St. Louis, and colleagues investigated the effect of poverty on brain development by examining white and cortical gray matter, as well as hippocampus and amygdala volumes in a group of children ages 6 to 12 years who were followed since preschool. The 145 children were recruited from a larger group of children who participated in a preschool depression study.

The authors report that "exposure to poverty during early childhood is associated with smaller white mater, cortical gray matter, and hippocampal and amygdala volumes," the authors write.

Study findings also indicate that the effects of poverty on hippocampal volume were mediated (influenced) by caregiving and stressful life events.

"The finding that the effects of poverty on hippocampal development are mediated through caregiving and stressful life events further underscores the importance of high-quality early childhood caregiving, a task that can be achieved through parenting education and support, as well as through preschool programs that provide high-quality supplementary caregiving and safe haven to vulnerable young children," the study concludes. 

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Concussion damage looks like early Alzheimer's

Damage from concussions seen in brain scans of children resembles early Alzheimer's.

Concussion can lead to damage in the white matter of the brain that resembles abnormalities found in people in the early stages of Alzheimer's disease, a new study suggests.

Researchers at the University of Pittsburgh School of Medicine said their findings should prompt a re-evaluation of the long-term effects of concussion, which affects more than 1.7 million people in the United States annually. About 15 percent of concussion patients suffer persistent neurological symptoms.

"The previous thinking before was you get a concussion, and that causes a certain damage from bopping your head and you get these symptoms," said study author Dr. Saeed Fakhran, an assistant professor of radiology at the University of Pittsburgh School of Medicine. "We found it acts as a kind of trigger, and lights a fuse that causes a neurodegenerative cascade that causes all these symptoms down the line. Once you've hit your head, the injury isn't done."

The findings are published online June 18 in the journal Radiology.

The study drew some criticism from concussion and Alzheimer's disease experts who said the findings, while provocative, should not be interpreted as drawing a clear link between a concussion suffered early in life with the development of Alzheimer's.

"I don't want a mom to pick this up and say, 'Oh my god, my 10-year-old is going to get Alzheimer's now,' because that is not the case," said Dr. Ken Podell, a neuropsychologist and co-director of the Methodist Concussion Center in Houston. "It's very inconclusive at this time, and there's no clinical application of this at this point of time."

White matter serves as the tissue through which messages pass between different areas of gray matter within the brain and spinal cord. Think of gray matter as the individual computers in a network, and white matter as the cables that connect the computer.

The researchers reviewed past brain scans of 64 people who had suffered a concussion, focusing on scans that used an advanced MRI technique called diffusion-tensor imaging, which spots microscopic changes in the brain's white matter.

The investigators then compared these brain scans to symptoms reported by concussed patients in a post-concussion questionnaire. They focused on symptoms shared with Alzheimer's patients, including memory problems, disturbances in sleep cycles and hearing problems.

The results showed a significant correlation between high concussion symptom scores and reduced water movement in the parts of the brain's white matter related to auditory processing and sleep-wake disturbances. Further, the researchers said, the distribution of white matter abnormalities in mildly concussed patients resembled the distribution of abnormalities in people with Alzheimer's disease.

"Basically, it looks a lot like Alzheimer's," said study co-author Dr. Lea Alhilali, an assistant professor of radiology at the University of Pittsburgh School of Medicine. "You get the same distribution of damage in the way that Alzheimer's disease affects the brain."

These abnormalities could spark a series of reactions that lead to long-term problems with thinking and memory. "The cascade is what is the important factor," Alhilali said. "It doesn't appear what you're symptomatic from is the injury itself. What you're symptomatic from is how the brain responds to that injury."

However, brain experts believe that researchers may be going too far in trying to draw a link between the concussion damage they found and the chronic damage found in Alzheimer's.

"It's an interesting observation, but I think they are making a leap that the pattern of changes they see on the scan are indicative of what we see in Alzheimer's disease," said Dr. Ron Petersen, director of the Mayo Alzheimer's Disease Research Center. "Their correlation between the scores on the concussion instrument and white matter changes, that's nice and good and makes sense. But then they go into a rather extensive anatomical explanation of how this might be similar to Alzheimer's disease, and I find that a bit tenuous."

Podell listed a number of concerns with the article, including:

• The researchers' reliance on existing brain scans and symptom charts created by other people. "You don't know what questions were asked, who asked the questions, how they were asked," he said. "There are a lot of things you can't control for."
• The inclusion of young patients in the pool of subjects, who ranged in age from 10 to 38. "White matter is not fully developed in people until they are adults," he said. "You have 10-year-olds in this study. It is highly, highly unusual to mix young kids with adults, because the brain is so different."
• The use of sleep disturbance as a comparable symptom between concussion and Alzheimer's. "What's a common co-injury in concussion? Whiplash. You have neck pain, back pain," he said. "If you go to sleep, you don't think that pain wakes you up?"

"The issue is, does a single concussion in an individual mean they are at risk for developing Alzheimer's?" Podell said. "There are so many other factors involved, including genetic factors, management of a concussion and the general health and well-being of the individual throughout their life."

The study authors agreed that their findings are tentative.

"This is not a definitive study. This is not the end at all. This is the first step," Alhilali said. "We hope this will lead to more research that will further explore this potential link."

The researchers do believe their findings could lead to better treatments in the future, however.

"The first step in developing a treatment for any disease is understanding what causes it," Fakhran said. "If we can prove a link, or even a common pathway, between mild traumatic brain injury and Alzheimer's, this could potentially lead to treatment strategies that would be potentially efficacious in treating both diseases."

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Alcohol and Marijuana Use in Youth can Compromise White Matter in Brain

Research into how alcohol and marijuana use affects children's brains showed that the integrity of white matter can be compromised.

Chronic use of alcohol and marijuana during youth is associated with poorer neural structure, function, and metabolism, as well as worsened neurocognitive abilities into later adolescence and adulthood. This may be due to biological and psychosocial transitions occurring during adolescence that impart increased vulnerability to neurotoxic influences. A study of longitudinal changes in fiber tract integrity associated with adolescent alcohol and marijuana use during 1.5 years supports previous findings of reduced white-matter integrity in these youth.

Results will be published in a special online issue of Alcoholism: Clinical & Experimental Research and are currently available at Early View.

"Research has shown differences in the brains of teens who use alcohol and marijuana as compared to teens who do not use these drugs or report only very infrequent, minimal use," said Joanna Jacobus, postdoctoral fellow at the University of California, San Diego as well as corresponding author for the study. "Alcohol and marijuana may have a negative impact by altering important cellular communication in the brain, preventing development of new healthy cells, and/or causing inflammation, which can adversely impact healthy brain development in many ways. For example, the results can lead to changes in brain structure such as volume, and function such as activity."

"The areas of the brain that are composed mostly of connecting axons have been termed 'white matter,' since these areas appear white in color," added Duncan Clark, associate professor of psychiatry at the University of Pittsburgh Medical Center. "However, prior research has not clearly demonstrated that this white matter disorganization is caused by alcohol or marijuana use. In some studies where adolescents are studied only once, white matter disorganization may have been present prior to alcohol or marijuana use."

"The teen brain is continuing to develop, so many neural systems are not yet fully matured, as compared to adults' brains," said Jacobus. "Brain connections important for inhibiting risky behaviors are still forming, and some youth are more likely to choose immediate effects, such as alcohol or marijuana use, over long-term benefits."

Clark agreed. "Maturation of the brain during adolescence is thought to be the foundation for self-control," he said. "The developing adolescent brain, compared to the fully developed adult brain, is also probably more vulnerable to alcohol neurotoxicity. Adolescents are vulnerable to loss of control and, when this loss of control involves substance use, excessive or risky substance use can have adverse consequences."

For 18 months, the researchers followed 92 adolescents (63 males, 29 females), ages 16 to 20 years, divided into two groups: 41 with extensive alcohol and marijuana use histories by mid-adolescence, and 51 with consistently minimal if any substance use. Participants were part of an ongoing longitudinal study of substance use in adolescence with teens recruited from local schools from 2005 to 2007. Both groups received diffusion tensor imaging and detailed substance use assessments, along with toxicology screening, at baseline and 18-month follow-ups -- 182 scans in all -- as well as interim substance-use interviews every six months.

"We found evidence for poorer white matter tissue health in teens who engage in heavy alcohol and marijuana use compared to those who abstain," said Jacobus. She noted that white matter, the "information highway of the brain," allows for quick and efficient communication between brain regions. Compromised white matter can mean slower cognitive processing and poorer cognitive performance such as memory, attention, and decision-making.

"As to whether there were differences in these teens before they began using alcohol and marijuana is difficult to determine, but we found that increasing alcohol use over 1.5 years in late adolescence was related to a decline in white matter health 18 months later, supporting a negative effect of alcohol use on the brain despite potential pre-existing differences," Jacobus said.

"White matter organization was particularly compromised in an area called the superior longitudinal fasciculus," added Clark. "This is one of the major connection roadways in the brain. When the connections between brain areas are severely damaged, those areas of the brain cannot properly function. While the more subtle deficit shown here may impair functioning, the degree of deficit involved is not likely to be obvious in day-to day functioning. However, we are concerned that even these subtle deficits in brain microstructure may lead to diminished self-control."

"Our findings underscore that early initiation of alcohol and marijuana use can have negative implications on the brain" said Jacobus. "We hope this information can be communicated to teens to help them understand why drinking during adolescence is discouraged. In the future, biomarkers such as tissue health may help identify teens that are particularly vulnerable for engaging in riskier behaviors such as drinking."

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