Posts tagged brain structure
Articles and news from the latest research reports.
Fish study links brain size to parental duties
Male stickleback fish that protect their young have bigger brains than counterparts that don’t care for offspring, finds a new University of British Columbia study.
Stickleback fish are well known in the animal kingdom for the fact that the male of the species, rather than the female, cares for offspring. Male sticklebacks typically have bigger brains than females and researchers wanted to find out if the difference in size might relate to their role as caregivers.
In the study, published recently in Ecology and Evolution, researchers compared regular male sticklebacks to male white sticklebacks, which do not tend to their offspring. They found evidence that this change in male behaviour – giving up caring for the young – occurred at the same time the white stickleback evolved a smaller brain.
“This suggests that regular sticklebacks have bigger brains to handle the brain power needed to care for and protect their young,” says Kieran Samuk, a PhD student in UBC’s Dept. of Zoology and the study’s lead author. “This is one of the first studies to link parental care with brain size.”
The white stickleback is a relatively young species that only diverged from other sticklebacks 10,000 years ago, offering researchers some insight into how quickly brains can evolve.
“Our study tells us that brains might change in very drastic ways in a relatively short period of time. This helps us understand how physical changes such as brain size can lead to more complex behavioural changes,” says Samuk.
Dementia Risk Quadrupled in People with Mild Cognitive Impairment
In a long-term, large-scale population-based study of individuals aged 55 years or older in the general population researchers found that those diagnosed with mild cognitive impairment (MCI) had a four-fold increased risk of developing dementia or Alzheimer’s disease (AD) compared to cognitively healthy individuals. Several risk factors including older age, positive APOE-ɛ4 status, low total cholesterol levels, and stroke, as well as specific MRI findings were associated with an increased risk of developing MCI. The results are published in a supplement to the Journal of Alzheimer’s Disease.
“Mild cognitive impairment has been identified as the transitional stage between normal aging and dementia,” comments M. Arfan Ikram, MD, PhD, a neuroepidemiologist at Erasmus MC University Medical Center (Rotterdam). “Identifying persons at a higher risk of dementia could postpone or even prevent dementia by timely targeting modifiable risk factors.”
Unlike a clinical trial, the Rotterdam study is an observational cohort study focusing on the general population, instead of persons referred to a memory clinic. The Rotterdam study began in 1990, when almost 8,000 inhabitants of Rotterdam aged 55 years or older agreed to participate in the study. Ten years later, another 3,000 individuals were added. Participants undergo home interviews and examinations every four years.
“This important prospective study adds to the accumulating evidence that strokes, presumably related to so called ‘vascular’ risk factors, also contribute to the appearance of dementia in Alzheimer’s disease. This leads to the conclusion that starting at midlife people should minimize those risk factors. The recent results of the Finish FINGER study corroborate this idea. It should be remembered that delaying the onset of dementia by five years will reduce the prevalence of the disease by half. And of course, since there is no cure for AD, prevention is the best approach at present,” explains Professor Emeritus Amos D Korczyn, Tel Aviv University, Ramat Aviv, Israel, and Guest Editor of the Supplement.
To be diagnosed with MCI in the study, individuals were required to meet three criteria: a self-reported awareness of having problems with memory or everyday functioning; deficits detected on a battery of cognitive tests; and no evidence of dementia. They were categorized into those with memory problems (amnestic MCI) and those with normal memory (non-amnestic MCI).
Of 4,198 persons found to be eligible for the study, almost 10% were diagnosed with MCI. Of these, 163 had amnestic MCI and 254 had non-amnestic MCI.
The risk of dementia was especially high for people with amnestic MCI. Similar results were observed regarding the risk for Alzheimer’s disease. Those with MCI also faced a somewhat higher risk of death.
The research team investigated possible determinants of MCI, considering factors such as age, APOE-ɛ status, waist circumference, hypertension, diabetes mellitus, total and HDL-cholesterol levels, smoking, and stroke. Only older age, being an APOE-ɛ4 carrier, low total cholesterol levels, and stroke at baseline were associated with developing MCI. Having the APOE-ɛ4 genotype and smoking were related only to amnestic MCI.
When the investigators analysed MRI studies of the brain, they found that participants with MCI, particularly those with non-amnestic MCI, had larger white matter lesion volumes and worse microstructural integrity of normal-appearing white matter compared to controls. They were also three-times more likely than controls to have lacunes (3 to 15 mm cerebrospinal fluid (CSF)-filled cavities in the basal ganglia or white matter, frequently observed when imaging older people). MCI was not associated with total brain volume, hippocampal volume, or cerebral microbleeds.
“Our results suggest that accumulating vascular damage plays a role in both amnestic and non-amnestic MCI,” says Dr. Ikram. “We propose that timely targeting of modifiable vascular risk factors might contribute to the prevention of MCI and dementia.”
Reference:
Determinants, MRI Correlates, and Prognosis of Mild Cognitive Impairment: The Rotterdam Study. Renée F.A.G. de Bruijn, Saloua Akoudad, Lotte G.M. Cremers, Albert Hofman, Wiro J. Niessen, Aad van der Lugt, Peter J. Koudstaal, Meike W. Vernooij, M. Arfan Ikram. Journal of Alzheimer’s Disease, Volume 42/Supplement 3 (August 2014): 2013 International Congress on Vascular Dementia (Guest Editor: Amos D. Korczyn)
(Source: iospress.nl)
Eating Baked or Broiled Fish Weekly Boosts Brain Health
Eating baked or broiled fish once a week is good for the brain, regardless of how much omega-3 fatty acid it contains, according to researchers at the University of Pittsburgh School of Medicine. The findings, published online recently in the American Journal of Preventive Medicine, add to growing evidence that lifestyle factors contribute to brain health later in life.
Scientists estimate that more than 80 million people will have dementia by 2040, which could become a substantial burden to families and drive up health care costs, noted senior investigator James T. Becker, Ph.D., professor of psychiatry, Pitt School of Medicine. Some studies have predicted that lifestyle changes such as a reduction in rates of physical inactivity, smoking and obesity could lead to fewer cases of Alzheimer’s disease and other conditions of cognitive impairment in the elderly. The anti-oxidant effect of omega-3 fatty acids, which are found in high amounts in fish, seeds and nuts, and certain oils, also have been associated with improved health, particularly brain health.
“Our study shows that people who ate a diet that included baked or broiled, but not fried, fish have larger brain volumes in regions associated with memory and cognition,” Dr. Becker said. “We did not find a relationship between omega-3 levels and these brain changes, which surprised us a little. It led us to conclude that we were tapping into a more general set of lifestyle factors that were affecting brain health of which diet is just one part.”
Lead investigator Cyrus Raji, M.D., Ph.D., who now is in radiology residency training at UCLA, and the research team analyzed data from 260 people who provided information on their dietary intake, had high-resolution brain MRI scans, and were cognitively normal at two time points during their participation in the Cardiovascular Health Study (CHS), a 10-year multicenter effort that began in 1989 to identify risk factors for heart disease in people over 65.
“The subset of CHS participants answered questionnaires about their eating habits, such as how much fish did they eat and how was it prepared,” Dr. Raji said. “Baked or broiled fish contains higher levels of omega-3s than fried fish because the fatty acids are destroyed in the high heat of frying, so we took that into consideration when we examined their brain scans.”
People who ate baked or broiled fish at least once a week had greater grey matter brain volumes in areas of the brain responsible for memory (4.3 percent) and cognition (14 percent) and were more likely to have a college education than those who didn’t eat fish regularly, the researchers found. But no association was found between the brain differences and blood levels of omega-3s.
“This suggests that lifestyle factors, in this case eating fish, rather than biological factors contribute to structural changes in the brain,” Dr. Becker noted. “A confluence of lifestyle factors likely are responsible for better brain health, and this reserve might prevent or delay cognitive problems that can develop later in life.”
Brain of World’s First Known Predators Discovered
An international team of paleontologists has identified the exquisitely preserved brain in the fossil of one of the world’s first known predators that lived in the Lower Cambrian, about 520 million years ago. The discovery revealed a brain that is surprisingly simple and less complex than those known from fossils of some of the animal’s prey.
The find for the first time identifies the fossilized brain of what are considered the top predators of their time, a group of animals known as anomalocaridids, which translates to “abnormal shrimp.” Long extinct, these fierce-looking arthropods were first discovered as fossils in the late 19th century but not properly identified until the early 1980s. They still have scientists arguing over where they belong in the tree of life.
"Our discovery helps to clarify this debate," said Nicholas Strausfeld, director of the University of Arizona’s Center for Insect Science. "It turns out the top predator of the Cambrian had a brain that was much less complex than that of some of its possible prey and that looked surprisingly similar to a modern group of rather modest worm-like animals."
Strausfeld, a Regents’ Professor in the Department of Neuroscience in the UA College of Science, is senior author on a paper about the findings, which appear in the July 17 issue of Nature.
Study Identifies Predictors for Teen Binge-Drinking
Neuroscientists leading the largest longitudinal adolescent brain imaging study to date have learned that predicting teenage binge-drinking is possible. In fact, say the researchers in the group’s latest publication, a number of factors – genetics, brain function and about 40 different variables – can help scientists predict with about 70 percent accuracy which teens will become binge drinkers. The study appears online July 3, 2014 as an Advance Online Publication in the journal Nature.
First author Robert Whelan, Ph.D., a former University of Vermont (UVM) postdoctoral fellow in psychiatry and current lecturer at University College Dublin, and senior author Hugh Garavan, Ph.D., UVM associate professor of psychiatry, and colleagues conducted 10 hours of comprehensive assessments – these included neuroimaging to assess brain activity and brain structure, along with other measures such as IQ, cognitive task performance, personality and blood tests – on each of 2,400 14-year-old adolescents at eight different sites across Europe.
“Our goal was to develop a model to better understand the relative roles of brain structure and function, personality, environmental influences and genetics in the development of adolescent abuse of alcohol,” says Whelan. “This multidimensional risk profile of genes, brain function and environmental influences can help in the prediction of binge drinking at age 16 years.”
A 2012 Nature Neuroscience paper by the same researchers identified brain networks that predisposed some teens to higher-risk behaviors like experimentation with drugs and alcohol. This new study develops on that earlier work by following those kids for years (the participants in the study are now 19 years old) and identifying those who developed a pattern of binge-drinking. The 2014 Nature study aimed to predict those who went on to drink heavily at age 16 using only data collected at age 14. They applied a broad range of measures, developing a unique analytic method to predict which individuals would become binge-drinkers. The reliability of the results were confirmed by showing the same accuracy when tested on a new, separate group of teenagers. The result was a list of predictors that ranged from brain and genetics to personality and personal history factors.
“Notably, it’s not the case that there’s a single one or two or three variables that are critical,” says Garavan. “The final model was very broad – it suggests that a wide mixture of reasons underlie teenage drinking.”
Some of the best predictors, shares Garavan, include variables like personality, sensation-seeking traits, lack of conscientiousness, and a family history of drug use. Having even a single drink at age 14, was also a powerful predictor. That type of risk-taking behavior – and the impulsivity that often accompanies it – was a critical predictor. In addition, those teens who had experienced several stressful life events were among those at greater risk for binge-drinking.
One interesting finding, says Garavan, was that bigger brains were also predictive. Adolescents undergo significant brain changes, so in addition to the formation of personalities and social networks, it’s actually normal for their brains to reduce to a more efficient size.
“There’s refining and sculpting of the brain, and most of the gray matter – the neurons and the connections between them, are getting smaller and the white matter is getting larger,” he explains. “Kids with more immature brains – those that are still larger – are more likely to drink.”
Garavan, Whelan and colleagues believe that by better understanding the probable causal factors for binge-drinking, targeted interventions for those most at risk could be applied.
Gunter Schumann, M.D.,professor of biological psychiatry and head of the section at the Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King’s College London, is the principle investigator of the IMAGEN study, which is the source of this latest paper. “We aimed to develop a ‘gold standard’ model for predicting teenage behavior, which can be used as a benchmark for the development of simpler, widely applicable prediction models,” says Schumann. “This work will inform the development of specific early interventions in carriers of the risk profile to reduce the incidence of adolescent substance abuse. We now propose to extend analysis of the IMAGEN data in order to investigate the development of substance use patterns in the context of moderating environmental factors, such as exposure to nicotine or drugs as well as psychosocial stress.”
In the future, the researchers hope to perform more in-depth analyses of the brain factors involved and determine whether or not there are different predictors for abuse of other drugs. A similar analysis, which is using the same dataset to look at the predictors of cannabis use, is planned for the near future.
(Source: uvm.edu)
Exposure to TV Violence Related to Irregular Attention and Brain Structure
Young adult men who watched more violence on television showed indications of less mature brain development and poorer executive functioning, according to the results of an Indiana University School of Medicine study published online in the journal Brain and Cognition.
The researchers used psychological testing and MRI scans to measure mental abilities and volume of brain regions in 65 healthy males with normal IQ between the age of 18 and 29, specifically chosen because they were not frequent video game players.
Lead author Tom A. Hummer, Ph.D., assistant research professor in the IU Department of Psychiatry, said the young men provided estimates of their television viewing over the past year and then kept a detailed diary of their TV viewing for a week. Participants also completed a series of psychological tests measuring inhibitory control, attention and memory. At the conclusion, MRI scans were used to measure brain structure.
Executive function is the broad ability to formulate plans, make decisions, reason and problem-solve, regulate attention, and inhibit behavior in order to achieve goals.
"We found that the more violent TV viewing a participant reported, the worse they performed on tasks of attention and cognitive control," Dr. Hummer said. "On the other hand, the overall amount of TV watched was not related to performance on any executive function tests."
Dr. Hummer noted that these executive functioning abilities can be important for controlling impulsive behaviors, including aggression. “The worry is that more impulsivity does not mix well with the behaviors modeled in violent programming.”
Tests that measured working memory, another subtype of executive functioning, were not found to be related to overall or violent TV viewing.
Comparing TV habits to brain images also produced results that Dr. Hummer and colleagues believe are significant.
"When we looked at the brain scans of young men with higher violent television exposure, there was less volume of white matter connecting the frontal and parietal lobes, which can be a sign of less maturity in brain development," he said.
White matter is tissue in the brain that insulates nerve fibers connecting different brain regions, making functioning more efficient. In typical development, the amount or volume of white matter increases as the brain makes more connections until about age 30, improving communication between regions of the brain. Connections between the frontal and parietal lobes are thought to be especially important for executive functioning.
"The take-home message from this study is the finding of a relationship between how much violent television we watch and important aspects of brain functioning like controlled attention and inhibition," Dr. Hummer said.
Dr. Hummer cautions that more research is needed to better understand the study findings.
"With this study we could not isolate whether people with poor executive function are drawn to programs with more violence or if the content of the TV viewing is responsible for affecting the brain’s development over a period of time," Dr. Hummer said. "Additional longitudinal work is necessary to resolve whether individuals with poor executive function and slower white matter growth are more drawn to violent programming or if exposure to media violence modifies development of cognitive control," Dr. Hummer said.
(Source: newswise.com)
Creatures of habit: disorders of compulsivity share common pattern and brain structure
In a study published in the journal Molecular Psychiatry and primarily funded by the Wellcome Trust, researchers show that people who are affected by disorders of compulsivity have lower grey matter volumes (in other words, fewer nerve cells) in the brain regions involved in keeping track of goals and rewards.
In our daily lives, we make decisions based either on habit or aimed at achieving a specific goal. For example, when driving home from work, we tend to follow habitual choices – our ‘autopilot’ mode – as we know the route well; however, if we move to a nearby street, we will initially follow a ‘goal-directed’ choice to find our way home – unless we slip into autopilot and revert to driving back to our old home. However, we cannot always control the decision-making process and make repeat choices even when we know they are bad for us – in many cases this will be relatively benign, such as being tempted by a cake whilst slimming, but extreme cases it can lead to disorders of compulsivity.
In order to understand what happens when our decision-making processes malfunction, a team of researchers led by the Department of Psychiatry at the University of Cambridge compared almost 150 individuals with disorders including methamphetamine dependence, obesity with binge eating and obsessive compulsive disorder, comparing them with healthy volunteers of the same age and gender.
Study participants first took part in a computerised task to test their ability to make choices aimed a receiving a reward over and above making compulsive choices. In a second study, the researchers compared brain scans taken using magnetic resonance imaging (MRI) in healthy individuals and a subset of obese individuals with or without binge eating disorder (a subtype of obesity in which the person binge eats large amounts of food rapidly).
The researchers demonstrated that all of the disorders were connected by a shift away from goal-directed behaviours towards automatic habitual choices. The MRI scans showed that obese subjects with binge eating disorder have lower grey matter volumes – a measure of the number of neurons – in the orbitofrontal cortex and striatum of the brain compared to those who do not binge eat; these brain regions are involved in keeping track of goals and rewards. Even in healthy volunteers, lower grey matter volumes were associated with a shift towards more habitual choices.
Dr Valerie Voon, principal investigator of the study, says: “Seemingly diverse choices – drug taking, eating quickly despite weight gain, and compulsive cleaning or checking – have an underlying common thread: rather that a person making a choice based on what they think will happen, their choice is automatic or habitual.
“Compulsive disorders can have a profoundly disabling effect of individuals. Now that we know what is going wrong with their decision making, we can look at developing treatments, for example using psychotherapy focused on forward planning or interventions such as medication which target the shift towards habitual choices.”
In Old Age, Lack of Emotion and Interest May Signal Your Brain Is Shrinking
Older people who have apathy but not depression may have smaller brain volumes than those without apathy, according to a new study published in the April 16, 2014, online issue of Neurology®, the medical journal of the American Academy of Neurology. Apathy is a lack of interest or emotion.
“Just as signs of memory loss may signal brain changes related to brain disease, apathy may indicate underlying changes,” said Lenore J. Launer, PhD, with the National Institute on Aging at the National Institutes of Health (NIH) in Bethesda, MD, and a member of the American Academy of Neurology. “Apathy symptoms are common in older people without dementia. And the fact that participants in our study had apathy without depression should turn our attention to how apathy alone could indicate brain disease.”
Launer’s team used brain volume as a measure of accelerated brain aging. Brain volume losses occur during normal aging, but in this study, larger amounts of brain volume loss could indicate brain diseases.
For the study, 4,354 people without dementia and with an average age of 76 underwent an MRI scan. They were also asked questions that measure apathy symptoms, which include lack of interest, lack of emotion, dropping activities and interests, preferring to stay at home and having a lack of energy.
The study found that people with two or more apathy symptoms had 1.4 percent smaller gray matter volume and 1.6 percent less white matter volume compared to those who had less than two symptoms of apathy. Excluding people with depression symptoms did not change the results.
Gray matter is where learning takes place and memories are stored in the brain. White matter acts as the communication cables that connect different parts of the brain.
“If these findings are confirmed, identifying people with apathy earlier may be one way to target an at-risk group,” Launer said.
Research sheds new light on impact of diabetes on the brain
The new findings published in the Diabetes Care journal reveal the extent of damage patients suffering with the disease can endure in areas of the brain called ‘grey matter’ – a key component of the central nervous system which is involved in touch and pain sensory perception.
During the study, which involved patients with Type 1 and Type 2 diabetes, researchers used recent advances in ground breaking brain imaging and analyses methods to take detailed nerve assessments of the brain using magnetic resonance imaging (MRI) techniques.
This revealed that the volume of certain brain regions in people with diabetic neuropathy was significantly lower compared to those without the disease. Previous studies have shown that the impact of the disease on the brain is limited and isolated to outside areas of the brain considered to be peripheral to core functions in the body.
The breakthrough could pave the way for better assessment and monitoring of the disease, which affects around a third of people with diabetes. This, in turn, could lead to better treatments for sufferers in the future.
Brain Anatomy Differences Between Deaf, Hearing Depend on First Language Learned
In the first known study of its kind, researchers have shown that the language we learn as children affects brain structure, as does hearing status. The findings are reported in The Journal of Neuroscience.
While research has shown that people who are deaf and hearing differ in brain anatomy, these studies have been limited to studies of individuals who are deaf and use American Sign Language (ASL) from birth. But 95 percent of the deaf population in America is born to hearing parents and use English or another spoken language as their first language, usually through lip-reading. Since both language and audition are housed in nearby locations in the brain, understanding which differences are attributed to hearing and which to language is critical in understanding the mechanisms by which experience shapes the brain.
“What we’ve learned to date about differences in brain anatomy in hearing and deaf populations hasn’t taken into account the diverse language experiences among people who are deaf,” says senior author Guinevere Eden, DPhil, director for the Center for the Study of Learning at Georgetown University Medical Center (GUMC).
Eden and her colleagues report on a new structural brain imaging study that shows, in addition to deafness, early language experience – English versus ASL – impacts brain structure. Half of the adult hearing and half of the deaf participants in the study had learned ASL as children from their deaf parents, while the other half had grown up using English with their hearing parents.
“We found that our deaf and hearing participants, irrespective of language experience, differed in the volume of brain white matter in their auditory cortex. But, we also found differences in left hemisphere language areas, and these differences were specific to those whose native language was ASL,” Eden explains.
The research team, which includes Daniel S. Koo, PhD, and Carol J. LaSasso, PhD, of Gallaudet University in Washington, say their findings should impact studies of brain differences in deaf and hearing people going forward.
“Prior research studies comparing brain structure in individuals who are deaf and hearing attempted to control for language experience by only focusing on those who grew up using sign language,” explains Olumide Olulade, PhD, the study’s lead author and post-doctoral fellow at GUMC. “However, restricting the investigation to a small minority of the deaf population means the results can’t be applied to all deaf people.”
(Image: iStockphoto)