Jeans and Kurtis..

New mechanistic insights into adaptive learning

The brain is a fantastically complex and mysterious device, too large and with too many internal connections to be entirely programmable genetically. Its internal connectivity must therefore self-organize, based on the one hand on genetically regulated biases and on experience and learning on the other. The brain can change its internal connectivity based, for example, on correlations between the inputs it receives and the consequences of actions associated with those inputs, in a phenomenon we generally call associative learning. There are, in our daily life, numerous examples of this type of learning; its consequence is that a smell or a tune on the radio can trigger memories from the past, which lay dormant for some time.

“Such a recall — to a smell, sound, taste, or any other sensory stimulus — is evidence of associative learning, and what interested us here was to understand the tricks used by the brain to make these associations specific”, says Gilles Laurent, Director at the Max Planck Institute for Brain Research.

Together with his former Caltech student and postdoctoral fellow Stijn Cassenaer, Gilles Laurent set out to examine the phenomenon using insects as model system. A structure of great importance for learning in the insect brain is called the mushroom body. It is composed of a great many neurons (several hundreds of thousands in honeybees for example), and has been shown to be indispensable for several forms of olfactory learning (that is, learning associated to smells). What Cassenaer and Laurent set out to do was to explain an apparent paradox: how can a given odour be specifically memorised following an association with a reward, knowing that the brain signals representing reward are broadcast broadly into the mushroom body and therefore, not specific on their own.

They found that the answer relies on an interaction between the reward signal and a synaptic phenomenon known as spike-timing-dependent plasticity (STDP), itself discovered some 15 years ago by Henry Markram and Bert Sakmann, then at Max Planck Institute for Medical Research in Heidelberg. The new results indicate that STDP on its own — the strengthening or weakening of synaptic connections between neurons, that depends on the firing of those neurons in quick succession of one another — serves as a “tag” for the synapses that need modifying. Once so identified, the nonspecific reward signal can act specifically, and does so only at those precisely marked synapses. Laurent: “The discovery of this modulation is just the beginning. The molecular underpinning as well the process associated with the read out of the memories, are areas of much need-exploration”.

The study, "Conditional modulation of spike-timing-dependent plasticity for olfactory learning," was funded by the Lawrence Hanson Chair at Caltech, the National Institutes on Deafness and other Communication Disorders, Caltech's Broad Fellows Program, the US Office of Naval Research, and the Max Planck Society.

More information: Stijn Cassenaer & Gilles Laurent, Conditional modulation of spike-timing-dependent plasticity for olfactory learning. Nature, 25 January 2012, DOI:10.1038/nature10776

 

Provided by Max-Planck-Gesellschaft

"New mechanistic insights into adaptive learning." January 27th, 2012. http://medicalxpress.com/news/2012-01-mechanistic-insights.html

 

Posted by
Robert Karl Stonjek

Body location plays part in scratching pleasure

An itch is just an itch. Or is it? New research from Gil Yosipovitch, M.D., Ph.D., professor of dermatology at Wake Forest Baptist Medical Center and a world-renowned itch expert, shows that how good scratching an itch feels is related to the itch's location.

While previous studies by Yosipovitch have shown the pleasurability of itching, analysis of itch relief at different body sites and related pleasurability had not been performed until now. The study was published online this month by the British Journal of Dermatology.

"The goal of this study was to examine the role of the pleasurability of scratching in providing relief for itch," Yosipovitch explained. "We first evaluated whether itch intensity was perceived differently at three body sites, and then we investigated the potential correlation between the pleasurability and the itch relief induced by scratching."

Yosipovitch and colleagues induced itch on the ankles, forearms and backs of 18 study participants with cowhage spicules, which come from a type of legume found in tropical areas that are known to cause intense itching. The spicules were rubbed gently in a circular motion for 45 seconds within a small area of the skin and removed with adhesive tape once itch was induced. Itch intensity and scratching pleasurability were assessed every 30 seconds for a duration of five minutes using a Visual Analog Scale (VAS) to rate intensity – 0 for no itch, up to 10 for maximum unbearable itch.

Their results show that itch was perceived most intensely at the ankle and back, while the perception of itch and scratching relief were less pronounced on the forearm. Another major finding of the paper, as Yosipovitch explains, is that "the pleasurability of scratching the ankle appears to be longer lived compared to the other two sites."

Yosipovitch said this research helps lead to a better understanding of itch and how to relieve it for people who have skin disease.

"We see commonly involved areas such as the ankle and back in itchy patients with skin disorders caused by eczema or psoriasis," he said. "We never understood why those areas were more affected, and now we better understand that itch in these areas is more intense and pleasurable to scratch."

Yosipovitch said that while it is known that small nerve fibers are involved in unpleasant sensations such as itch and pain, he and other researchers now suspect that there are also specific nerve fibers involved in pleasure.

"If we could translate this to a treatment that induces a pleasurable relief sensation without damaging the skin, we may be able to help itchy patients," he said.

Provided by Wake Forest Baptist Medical Center

"Body location plays part in scratching pleasure." January 27th, 2012. http://medicalxpress.com/news/2012-01-body-pleasure.html

 

Posted by
Robert Karl Stonjek

Making memories last: Prion-like protein plays key role in storing long-term memories

Drosophila Orb2 plays an important role in the persistence of memory. Upon stimulation, Orb2 (shown in yellow) forms amyloid-like oligomers (shown in red), which are an essential ingredient for the formation of long-term memory. Credit: Illustration: Nicolle Rager Fuller, Sayo-Art

Memories in our brains are maintained by connections between neurons called "synapses". But how do these synapses stay strong and keep memories alive for decades? Neuroscientists at the Stowers Institute for Medical Research have discovered a major clue from a study in fruit flies: Hardy, self-copying clusters or oligomers of a synapse protein are an essential ingredient for the formation of long-term memory.

The finding supports a surprising new theory about memory, and may have a profound impact on explaining other oligomer-linked functions and diseases in the brain, including Alzheimer's disease and prion diseases.

"Self-sustaining populations of oligomers located at synapses may be the key to the long-term synaptic changes that underlie memory; in fact, our finding hints that oligomers play a wider role in the brain than has been thought," says Kausik Si, Ph.D., an associate investigator at the Stowers Institute, and senior author of the new study, which is published in the January 27, 2012 online issue of the journalCell.

Si's investigations in this area began nearly a decade ago during his doctoral research in the Columbia University laboratory of Nobel-winning neuroscientist Eric Kandel. He found that in the sea slug Aplysia californica, which has long been favored by neuroscientists for memory experiments because of its large, easily-studied neurons, a synapse-maintenance protein known as CPEB (Cytoplasmic Polyadenylation Element Binding protein) has an unexpected property.

A portion of the structure is self-complementary and—much like empty egg cartons—can easily stack up with other copies of itself. CPEB thus exists in neurons partly in the form of oligomers, which increase in number when neuronal synapses strengthen. These oligomers have a hardy resistance to ordinary solvents, and within neurons may be much more stable than single-copy "monomers" of CPEB. They also seem to actively sustain their population by serving as templates for the formation of new oligomers from free monomers in the vicinity.

CPEB-like proteins exist in all animals, and in brain cells they play a key role in maintaining the production of other synapse-strengthening proteins. Studies by Si and others in the past few years have hinted that CPEB's tendency to oligomerize is not merely incidental, but is indeed essential to its ability to stabilize longer-term memory. "What we've lacked till now are experiments showing this conclusively," Si says.

In the new study, Si and his colleagues examined a Drosophila fruit fly CPEB protein known as Orb2. Like its counterpart in Aplysia, it forms oligomers within neurons. "We found that these Orb2 oligomers become more numerous in neurons whose synapses are stimulated, and that this increase in oligomers happens near synapses," says lead author Amitabha Majumdar, Ph.D., a postdoctoral researcher in Si's lab.

The key was to show that the disruption of Orb2 oligomerization on its own impairs Orb2's function in stabilizing memory. Majumdar was able to do this by generating an Orb2 mutant that lacks the normal ability to oligomerize yet maintains a near-normal concentration in neurons. Fruit flies carrying this mutant form of Orb2 lost their ability to form long-term memories. "For the first 24 hours after a memory-forming stimulus, the memory was there, but by 48 hours it was gone, whereas in flies with normal Orb2 the memory persisted," Majumdar says.

Si and his team are now following up with experiments to determine for how long Orb2 oligomers are needed to keep a memory alive. "We suspect that they need to be continuously present, because they are self-sustaining in a way that Orb2 monomers are not," says Si.

The team's research also suggests some intriguing possibilities for other areas of neuroscience. This study revealed that Orb2 proteins in the Drosophila nervous system come in a rare, highly oligomerization-prone form (Orb2A) and a much more common, much less oligomerization-prone form (Orb2B). "The rare form seems to be the one that is regulated, and it seems to act like a seed for the initial oligomerization, which pulls in copies of the more abundant form," Si says. "This may turn out to be a basic pattern for functional oligomers."

The findings may help scientists understand disease-causing oligomers too. Alzheimer's, Parkinson's and Huntington's disease, as well as prion diseases such as Creutzfeldt-Jakob disease, all involve the spread in the brain of apparently toxic oligomers of various proteins. One such protein, strongly implicated in Alzheimer's disease, is amyloid beta; like Orb2 it comes in two forms, the highly oligomerizing amyloid-beta-42 and the relatively inert amyloid-beta-40. Si's work hints at the possibility that oligomer-linked diseases are relatively common in the brain because the brain evolved to be relatively hospitable to CPEB proteins and other functional oligomers, and thus has fewer mechanisms for keeping rogue oligomers under control.

Provided by Stowers Institute for Medical Research

"Making memories last: Prion-like protein plays key role in storing long-term memories." January 27th, 2012.http://medicalxpress.com/news/2012-01-memories-prion-like-protein-key-role.html

 

Posted by

Robert Karl Stonjek

CAMH discovery identifies potential target for anti-craving medications

Scientists at the Centre for Addiction and Mental Health (CAMH) have identified a potential target for the development of anti-craving medications for people with addictions to stimulants such as methamphetamine.

The discovery centres on a brain receptor related to the chemical dopamine, which has a complex role in addictive behaviours.

Using brain scans and a novel chemical probe developed in CAMH's Research Imaging Centre, CAMH scientists found that the probe had high levels of binding to the dopamine D3 receptor in some people with methamphetamine addiction, compared with those who had no addiction. Higher levels of D3 were also linked to participants' reported motivation to take drugs.

"This is the first time, to our knowledge, that anyone has shown that D3 receptor levels are high in people with an active addiction to methamphetamine," says Dr. Isabelle Boileau, a scientist in the Research Imaging Centre, part of the new Campbell Family Research Institute at CAMH. Boileau led the study that appears in the January 25, 2012 issue of The Journal of Neuroscience.

Using positron emission tomography (PET), Boileau's team looked at D3 levels in 16 people who were dependent on methamphetamine. Participants abstained from methamphetamine use for 14 days prior to brain scans. Their results were compared with scans from 16 participants with no addiction. On a separate day after scanning, participants were given a low dose of amphetamine, and they had to report how much they wanted to use drugs.

D3 receptors appear to have a role in craving, but it is not fully established how they are related to drug-related behaviours. The new chemical probe developed at CAMH, called 11C-(+)-PHNO, binds to dopamine D3 receptors. This probe allows researchers to study D3 in people for the first time, using PET scans, in order to answer questions about its role in stimulant addiction.

Understanding the role of brain receptors in addiction has enabled researchers to develop treatment medications, such as nicotine replacement therapy for smoking. So far, therapeutic strategies for stimulant addiction have focused on increasing activity with D2 receptors, where binding levels have been low.

"We can now suggest that any therapeutic approach aimed at increasing activity with D2 receptors should consider being selective at targeting D2, and not increasing D3 levels," says Boileau. "Our finding also supports the idea that D3 should be considered another target for anti-craving medications."

Boileau is also looking at the role of D3 in different types of addictions, including cocaine and gambling.

Building on CAMH's record of innovation and discovery, the Campbell Family Mental Health Research Institute will be accelerating discoveries in the areas of mood disorders, addictions, schizophrenia and cognitive impairment.

CAMH's Research Imaging Centre is the first of its kind in Canada where positron emission tomography (PET), magnetic resonance imaging (MRI), and imaging-genetics are dedicated to the study of mental illness and addictions.

This new discovery is an example of the innovative brain science at CAMH's new Research Imaging Centre, the first of its kind in Canada where positron emission tomography (PET), magnetic resonance imaging (MRI), and genetic imaging are dedicated to the study of mental illness and addictions.

Provided by Centre for Addiction and Mental Health

"CAMH discovery identifies potential target for anti-craving medications." January 25th, 2012. http://medicalxpress.com/news/2012-01-camh-discovery-potential-anti-craving-medications.html

 

Posted by
Robert Karl Stonjek

New deep brain stimulation device shows promising results

(Medical Xpress) -- A multi-site study of a new deep brain stimulation device for people with Parkinson’s disease has found the device to provide benefits to patients, potentially paving the way for unprecedented competition in the area of neurostimulation technology.

The study, whose co-authors included George Mandybur, MD, an associate professor of neurosurgery at the University of Cincinnati (UC) College of Medicine and Mayfield Clinic neurosurgeon, and Fredy Revilla, MD, an associate professor of neurology and UC Health neurologist, was published Jan. 11, 2012, in the online edition of Lancet Neurology. Mandybur and Revilla are members of the James J. and Joan A. Gardner Center for Parkinson’s Disease and Movement Disorders at the UC Neuroscience Institute, a specialty center within UC Health.

Principal investigator of the study was Michael Okun, MD, a neurologist and co-director of the Center for Movement Disorders and Neurorestoration at the University of Florida College of Medicine.

Deep brain stimulation (DBS) devices stimulate the subthalamic nucleus deep within the brain. Deep brain stimulation surgery has been shown to reduce symptoms of Parkinson’s and to improve quality of life.

The Lancet Neurology study examined the new Libra and LibraXP devices, which are manufactured by St. Jude Medical. The devices provide a constant, fixed-dose current, in contrast to the voltage-controlled device by Medtronic, Inc., which features a variable current and is the only DBS device on the market.

Participants in the randomized, controlled trial whose stimulators were turned on shortly after surgery experienced an increase of four hours of "on time” (with minimal symptoms), three months into the study. These benefits were significantly greater—2.5 more hours of "on time”—than those experienced by participants in the control group, whose stimulators were not turned on until the three-month mark.

Mandybur, who implanted the devices in 12 study participants at UC Health University Hospital, said the constant-current device compares favorably with the FDA-approved voltage-controlled device currently in use.

"This is the first study to look at constant-current effectiveness in Parkinson’s disease,” Mandybur says. "The new device appeared to be every bit as effective as the voltage-controlled device, but we won’t know for sure until there is a head-to-head comparison in future clinical trials. The devices are not identical.”

The St. Jude Neuromodulation Division, which funded the study, has applied for and is awaiting approval from the U.S. Food and Drug Administration for the Libra and LibraXP neurostimulators, which are currently available in Europe, Latin America and Australia.

The study results likely signal the imminent arrival of a competitor into a market currently filled only by Medtronic. "It will stir competition and it will light fires under people to develop new technology,” Mandybur says. "The same thing happened in the area of spinal cord stimulators.”

Revilla predicts that the new constant-current option will inspire Medtronic to create a constant-current option as well. "With further study,” he adds, "we may be able to establish clearly the differences and similarities of these two technologies.” 

Researchers theorize that constant-current stimulation might provide more accurate control of the spread of the electrical field than voltage-controlled stimulation. "But fundamental differences are unlikely,” writes Jens Volkmann, MD, of University Hospital of Würzburg, Germany, in an accompanying editorial in Lancet Neurology.

Parkinson’s disease, which afflicts more than 1 million Americans, is a degenerative neurological disorder involving the death of dopamine-producing nerve cells deep within the brain. There is no cure for Parkinson’s at this time, and scientists do not yet know how to halt its progression. Recent studies have shown that neurostimulation may slow the progression of the disease.

Candidates for deep brain stimulation are those who respond well to dopamine but over time have developed intolerable side-effects (mainly dyskinesias) and short duration of benefit.

 "When a person with Parkinson's develops wide motor fluctuations, requiring frequent doses of medications, along with intolerable side effects, it is time for DBS surgery,” Revilla says. "But it is still a requirement that the patient experience some benefit from the medications, even if it is short-lived.”

Revilla praised the 15 institutions whose close collaboration resulted in a study "that we expect will allow us to have alternative options for programming deep brain stimulation in patients who don’t respond well to conventional medical treatments.”

The Gardner Center team enrolled 12 patients, the second-highest number of any of the participating centers. (The highest enrollment was 13.)

Mandybur has received honoraria from Medtronic, Inc. Revilla is a consultant for Lundbeck, Inc.

Provided by University of Cincinnati

"New deep brain stimulation device shows promising results." January 25th, 2012. http://medicalxpress.com/news/2012-01-deep-brain-device-results.html

 

Posted by
Robert Karl Stonjek

Experiences are better when we know they're about to end

 

(Medical Xpress) -- People often view the "last" moments of an event positively simply because they signal the end of an experience, say University of Michigan researchers.

Even if the experience is painful or negative, but concludes on a pleasant note, people will consider the event a more positive experience, says Ed O'Brien, a graduate student in the U-M Department of Psychology.

"Endings are powerful," he said.

O'Brien and colleague Phoebe Ellsworth, the Frank Murphy Distinguished Professor of Law and Psychology, conducted a chocolate tasting experiment with 52 college students to test the theory.

Volunteers could sample five different Hershey's Kisses chocolates (milk, dark, crème, caramel and almond), but did not know in advance how many pieces they would eat or the type. Participants rated how much they enjoyed the chocolate and described each flavor so that the researchers could record the order in which the randomly pulled treats were eaten.

Volunteers were randomly assigned to the "next" or the "last" condition. In the "next" condition, the experimenter said, "Here is your next chocolate," before offering each chocolate, including the fifth.

For the "last" condition, the experimenter said, "Here is your last chocolate," before offering the fifth chocolate. These participants rated the fifth chocolate more enjoyable than volunteers in the "next" condition.

As predicted, participants who knew they were eating the final chocolate of a taste test enjoyed it more. In fact, when asked to pick their favorite chocolate, the majority of "last" participants chose the fifth—even though the flavor of the fifth was randomly chosen. They also rated the overall experience as more enjoyable than volunteers who thought they were just eating one more chocolate in a series.

O'Brien says these findings may have far-reaching implications. For example, the last book in a series or last speaker in a symposium may receive unwarranted praise simply because they are at the end of a series. The last job applicant may look more qualified.

More information: The findings appear in the current issue of Psychological Science

 

Provided by University of Michigan

"Experiences are better when we know they're about to end." January 25th, 2012. http://medicalxpress.com/news/2012-01-theyre.html

 

Posted by
Robert Karl Stonjek

Being ignored hurts, even by a stranger

 

(Medical Xpress) -- Feeling like you’re part of the gang is crucial to the human experience. All people get stressed out when we’re left out. A new study published in Psychological Science, a journal of the Association for Psychological Science, finds that a feeling of inclusion can come from something as simple as eye contact from a stranger.

Psychologists already know that humans have to feel connected to each other to be happy. A knitting circle, a church choir, or a friendly neighbor can all feed that need for connection. Eric D. Wesselmann of Purdue University wanted to know just how small a cue could help someone feel connected. He cowrote the study with Florencia D. Cardoso of the Universidad Nacional de Mar del Plata in Argentina, Samantha Slater of Ohio University, and Kipling D. Williams of Purdue. “Some of my coauthors have found, for example, that people have reported that they felt bothered sometimes even when a stranger hasn’t acknowledged them,” Wesselmann says. He and his authors came up with an experiment to test that.

The study was carried out with the cooperation of people on campus at Purdue University. A research assistant walked along a well-populated path, picked a subject, and either met that person’s eyes, met their eyes and smiled, or looked in the direction of the person’s eyes, but past them—past an ear, for example, “looking at them as if they were air,” Wesselmann says. When the assistant had passed the person, he or she gave a thumbs-up behind the back to indicate that another experimenter should stop that person. The second experimenter asked, “Within the last minute, how disconnected do you feel from others?”

People who had gotten eye contact from the research assistant, with or without a smile, felt less disconnected than people who had been looked at as if they weren’t there.

“These are people that you don’t know, just walking by you, but them looking at you or giving you the air gaze—looking through you—seemed to have at least momentary effect,” Wesselmann says. Other research has found that even being ostracized by a group you want nothing to do with, like the Ku Klux Klan, can make people feel left out, so it’s not surprising that being pointedly ignored can have the same effect. “What we find so interesting about this is that now we can further speak to the power of human social connection,” Wesselmann says. “It seems to be a very strong phenomenon.”

More information: http://www.psychol … ical_science

 

Provided by Association for Psychological Science

"Being ignored hurts, even by a stranger." January 25th, 2012. http://medicalxpress.com/news/2012-01-stranger.html

 

Posted by
Robert Karl Stonjek

Long-term effect of war on healthcare costs

(Medical Xpress) -- In the largest study of its kind, researchers have found that exposure to war and its effect on mental health are linked to a substantial increase in health care costs which remain high many years after the conflict.  

The research from King's College London Institute of Psychiatry, published in this month's PLoS ONE, suggests that costs remain especially high for those who stayed in the conflict zone compared to those who migrated. 

Researchers interviewed over 4,000 people who had experienced war around eight years previously in the former-Yugoslavia – these were mainly from Bosnia-Herzegovina, Croatia, Kosovo, FYR Macedonia, Serbia as well as refugees in Germany, Italy and the UK. 

The project team at the Institute of Psychiatry, Ramon Sabes-Figuera and Professor Paul McCrone, analysed the impact of individual characteristics such as age, sex, mental health status, and exposure to traumatic events before, during and after the wars, on the cost of services. 

In the Balkan countries, individual healthcare costs were increased by 63% if Post-Traumatic Stress Disorder was present and 73% if mood disorders were present. In the West, costs were increased by 77% and 63% with the presence of other anxiety disorders (e.g. phobias, obsessive compulsive disorder) and mood disorders respectively.  

In the Balkans, those with more traumatic events were more likely to have used health services. However in Western countries, exposure to more traumatic events was not linked to an increase in service use.  Reasons for this are uncertain.

Mr Sabes-Figuera, lead author of the study at the IoP, says: ‘So far, little has been known about the costs of healthcare for those involved in or affected by war. Estimating these costs and identifying their predictors can help inform appropriate service planning in the regions directly affected by conflict, and in the areas that welcomed high numbers of refugees. Assessment of these costs becomes even more important in lower income countries with limited health care funds which are disproportionately affected by war.’

The authors conclude that focussing on the mental health impact of war is important for an economic perspective as well as a public health perspective. In planning local mental health services the presence of people affected by war and conflict needs to be taken into account and it should be recognised that economic effects can be prolonged. 

The study was funded by a grant from the European Commission and the principal investigator was Stefan Priebe from Queen Mary College London.

More information: For full paper: Sabes-Figuera, R. et al. ‘Long-term impact of war on healthcare costs: an eight country study’ PLoS ONE (January 2012) doi:10.1371/journal.pone.0029603

 

Provided by King's College London

"Long-term effect of war on healthcare costs." January 26th, 2012. http://medicalxpress.com/news/2012-01-long-term-effect-war-healthcare.html

 

Posted by
Robert Karl Stonjek

Fear dementia? Your diet, weight more important than genes, experts say

Anyone who has a close relative with Alzheimer's shares the same worry: Am I next? However, a growing body of research indicates that our lifestyles - particularly what we eat and whether we're obese - play a greater role than our genes in determining our brain health as we age.

"For years, scientists thought that Alzheimer's was primarily genetic," said Gary Wenk, professor of neuroscience at Ohio State University. "We now believe that, while there's a genetic component, Alzheimer's is primarily a lifestyle disease."

People do carry genes, including APOE-4, that predispose them toward the disease, but whether they activate those genes depends heavily on their lifestyles, said Dr. Stuart Lipton, professor at Sanford-Burnham Research Institute, where he's scientific director of neuroscience, aging and stem-cell research.

"A myth exists that if the Alzheimer's gene is in your family, you're going to get it. But that only affects 1 percent of cases," Lipton said. "What matters most is how you superimpose your lifestyle on top of your genetic background."

A degenerative brain disorder that causes progressive loss of memory and intellectual and social skills, Alzheimer's is the most common form of dementia, affecting 5.4 million Americans, nearly half a million in Florida alone, according to the Alzheimer's Association. Though no cure exists, medications can slow progress.

Although Americans may have more control over whether they develop Alzheimer's than they thought, the primary risk factors are all on the rise.

"Looking at the rising rate of obesity, diabetes and metabolic syndrome, we're in a bad state of affairs," Lipton said.

Obesity is linked to Alzheimer's because it's a risk factor for diabetes, and diabetics have a two to three times greater risk of developing Alzheimer's, said Ira Goodman, a neurologist at Orlando Health. "We believe that's because their impaired ability to use or make insulin contributes to neurodegeneration" - in other words, brain breakdown.

Goodman, like other neuroscientists, recommends eating fewer carbohydrates, which keeps insulin levels down.

He cited a study out of the University of Cincinnati that found that carbohydrate restriction helped participants who had mild cognitive impairment regain mental function. Researchers divided the 23 participants into two groups. One group went on a typical diet consisting of 50 percent of calories from carbohydrates for six weeks. The other group went on a low-carbohydrate diet, where fewer than 10 percent of calories came from carbohydrates.

Afterward, cognitive function stayed about the same in the first group, while in the low-carb group, function improved, according to the 2010 study, published in the Neurobiology of Aging.

Brain experts also recommend a diet high in protein and rich in colorful fruits and vegetables. The latter are strong in polyphenols and anti-oxidants, which have proven to boost brain health.

Controlling stress is also important for optimizing brain function. Stress increases cortisol, a hormone, in the blood, which increases blood sugar, which increases insulin, Goodman said. The neuroscientist also does research at Compass Research in Orlando, where studies are under way looking for medications to prolong brain health and slow mental demise.

In a recent study at Yale, scientists found that stressful events appeared to cause gray matter - the brain tissue that contains dendrites, which transfer information between brain cells - to shrink. The cumulative effects of stress lead to cognitive impairment and probably to memory loss, said researcher Rajita Sinha, professor of psychiatry at Yale Medical School and director of the Yale Interdisciplinary Stress Center.

Yale researchers asked 103 healthy volunteers ages 18 to 48 to fill out questionnaires to quantify the amount of stress they'd had in their lives. Then participants underwent brain scans.

Subjects who had experienced recent stressful events, such as loss of a job, house or loved one, showed markedly lower amounts of gray matter in the prefrontal cortex, according to the study published in a recent issue of Society of Biological Psychiatry.

"The dendrites shrink with high levels of stress," Sinha said. "But all is not lost. The brain is dynamic and plastic. If the stress is dealt with in a healthy manner, dendrites grow back."

A healthful manner includes all the behaviors that help keep Alzheimer's at bay: keeping blood-sugar levels steady, exercising, building good personal relationships and engaging in positive activities, Sinha said.

Of course, another primary risk factor for Alzheimer's is getting older. Today, the chances of having Alzheimer's by the time a person reaches age 85 is 50 percent, Goodman said. That risk rises to 75 percent by age 100.

"Even if you do carry a genetic predisposition, lifestyle modifications in midlife can greatly reduce the risk and delay onset," Goodman said.

---

MORE WAYS TO WARD OFF ALZHEIMER'S

-Coffee drinkers and those who partake in a little wine each day also enjoy some protective benefits, said Gary Wenk, professor of neuroscience at Ohio State University, and author of "Your Brain on Food."

Long-term global studies have shown that those who consume five cups of coffee a day reduce their incidence of diabetes by 50 percent, and that protection increases as coffee consumption goes up.

-Other brain-healthy behaviors include keeping cholesterol levels, blood pressure and inflammation under control. "What's good for your heart is good for your brain," said Ira Goodman, a neurologist who conducts Alzheimer's studies at Compass Research in Orlando, Fla.

-Patients who've taken statins for years to control their cholesterol seem to have some protection, as do those who keep their blood pressure down, with or without medication, Wenk said.

-Large epidemiological studies have suggested that anti-inflammatory medications also help. "Those who developed arthritis early and began taking nonsteroidal anti-inflammatories were at lower risk of developing Alzheimer's," Wenk said.

-Exercising your body and your brain also proves protective. "The more you learn, the more synapses you make," Goodman said. "Brain degeneration involves the breaking down of synapses, so the more you have the longer the brain takes to break down. This is why we think people who are highly educated have a lower incidence of Alzheimer's."

-Socializing with friends and being active in your faith also help, researchers say.

(c)2012 The Orlando Sentinel (Orlando, Fla.) 
Distributed by MCT Information Services

"Fear dementia? Your diet, weight more important than genes, experts say." January 26th, 2012. http://medicalxpress.com/news/2012-01-dementia-diet-weight-important-genes.html

 

Posted by
Robert Karl Stonjek