The role of some brain structures are better understood than others. For example, the hippocampus, a small S-shaped structure that lies just inside your temples, plays a specific role in memory for facts, such as the capital of France (Paris), or events, such as what you had for breakfast (in my case, oatmeal).

Our knowledge of the hippocampus comes, in part, from a rare surgical procedure where an epileptic patient known as H.M. had a large portion of his hippocampus removed to prevent seizures. Although after the operation he suffered fewer seizures, he could no longer form new memories, such as remembering his doctors’ faces. Upon each visit, he introduced himself as if seeing them for the first time.

Imaging studies of patients with PTSD and depression reveal that part of their brain actually shrinks. They have a smaller hippocampus.

Given the fact that conditions such as PTSD are characterized by smaller hippocampi and a decline in memory, it might be important for treatments to address these deficits. Notably, patients with the worst memory performance have the most difficulty recovering.

The road to a high-functioning, herculean memory seems to be paved with a robust hippocampus, and PTSD and depression studies indicate that the hippocampus is dynamic and can change over time, for better or worse. It’s unclear whether SSRIs would improve memory for a healthy adult, but there is an alternative action which has shown promise as a memory enhancer. Exercise, well-documented as a stress-reliever and mood-booster, also helps improve the ability to remember words, facts and ideas. Why might this be? Following a 30-minute jog, a person has elevated levels of nerve-growth chemicals such as Brain-Derived Neurotrophic Factor (BDNF) which causes nerve cells in the hippocampus to multiply. The release of BDNF may boost both mood and memory, possibly explaining why exercise remains one of the best natural anti-depressants.

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Persons with higher levels of leptin, a protein hormone produced by fat cells and involved in the regulation of appetite, may have an associated reduced incidence of Alzheimer disease and dementia, according to a study in the December 16 issue of JAMA.

Previous studies have shown that overweight and obesity in mid-life are associated with poorer cognitive function in the general population and an increased risk of dementia. There has been evidence that leptin exerts additional functions on the brain outside the hypothalamus (a region of the brain that controls body temperature, hunger, and thirst), according to background information in the article.

The researchers found that higher leptin levels were associated with a lower incidence of  dementia and AD. The incidence of dementia decreased gradually across increasing levels of leptin: a person with a baseline leptin level in the lowest quartile group had a 25 percent risk of developing AD after 12 years of follow-up, whereas the corresponding risk for a person in the top quartile group was only 6 percent.

“These findings are consistent with recent experimental data indicating that leptin improves memory function in animals through direct effects on the hippocampus and strengthens the evidence that leptin is a hormone with a broad set of actions in the central nervous system. Due to the exploratory character of the present analyses, we did not adjust for multiple comparisons and acknowledge that our findings require confirmation in independent samples,” the authors write.

“If our findings are confirmed by others, leptin levels in older adults may serve as one of several possible biomarkers for healthy brain aging and, more importantly, may open new pathways for possible preventive and therapeutic intervention. Further exploration of the molecular and cellular basis for the observed association may expand our understanding of the pathophysiology underlying brain aging and the development of AD.”
(JAMA 2009;302[23]:2565-2572. )

Scientists in Germany found that increased physical activity was associated with a lower incidence of dementia. In this study, researchers recruited 3,485 elderly residents in Bavaria and asked them about their physical activity. None of the participants had dementia at the start of the analysis, but after two years of follow-up, researchers found that those who exercised at least three times a week were half as likely to have developed dementia compared with people who reported no physical activity. Based on his results, says lead author Dr. Thorleif Etgen, a professor of psychiatry and psychotherapy at München University, “It doesn’t make a big difference if you have moderate or high physical activity. The important message is that you do any activity. And even if you start late in life, at 60 or 70, there is a benefit, for it’s never too late to start exercising.”

The key words are “moderate or high,” according to another study published Monday in the Archives. Dr. Qi Sun, a researcher at Harvard School of Public Health, analyzed 13,000 women participating in the Nurses’ Health Study and found that when it came to exercise, more was better. Compared with women who jogged for 20 minutes a week, those who jogged three hours a week or walked briskly for five hours a week were 76% more likely to age successfully, free of chronic illnesses such as cancer and heart disease, as well as mental and physical impairment.

Sun’s group found that this benefit occurred across all weight divisions, meaning that even among those who were overweight or obese, women who exercised improved their odds of aging without chronic disease. The effects may apply across different age groups as well; the women were at least 60 years old by the time they enrolled in the study, and while Sun was not able to determine how long they had been exercising prior to that, the results suggest that the health benefits are not limited to the young.

That was the same message of the final exercise paper in the journal, by researchers at University of Erlangen-Nuremberg in Germany. In this trial, a group of 246 elderly women were randomly assigned to an 18-month exercise regimen or a wellness program. The women participating in the four times weekly exercise sessions, which involved aerobics and balance and muscle training, improved their bone mineral density by nearly 2%. The women in the wellness group, which focused on walking, muscle relaxation and breathing skills, had a 0.33% increase in bone density over the same time period. Perhaps more important, participants in the exercise group saw no increase in their risk of experiencing a fracture-causing fall, compared with a 66% higher risk in the control group.

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A large, 5-year study showed that the people in their 70s who were the most active and adhered the best to a Mediterranean-style diet were 61–67 percent less likely to develop Alzheimer’s disease compared with the least active and least Mediterranean-minded of the group.

Exercise
The most active in the study group got about an hour and a half of exercise weekly. That’s just a few 30-minute walks a week — a pretty manageable commitment. Better yet, aim to walk 30 minutes every day.

Diet
People with the lowest dementia risk ate the highest amounts of fruit, veggies, legumes, and fish, but less meat and dairy products. Monounsaturated fats, like olive oil, also accounted for more of their fat intake than saturated fats. All very typical ratios in a Mediterranean-style diet that doctors and health experts alike recommend for all sorts of reasons. These nutrient-dense, healthy-fat-focused foods could help protect brains against disease and cognitive decline and help protect the body from lots of other bad things, too.

LONDON – Scientists have discovered a new source for the generation of nerve cells in the brain.

Professor Magdalena Gotz of Helmholtz Zentrum Munchen and Ludwig-Maximilians-Universitat (LMU) Munich and colleagues have discovered progenitor cells, which can form new glutamatergic neurons following injury to the cerebral cortex.

Particularly in Alzheimer’s disease, nerve cell degeneration plays a crucial role. In the future, new therapeutic options may possibly be derived from steering the generation and/or migration mechanism, according to the researchers.

Until only a few years ago, neurogenesis – the process of nerve cell development – was considered to be impossible in the adult brain.

Then researchers discovered regions in the forebrain in humans in which new nerve cells can be generated throughout life. These so-called GABAergic cells use gamma-aminobutyric acid (GABA), a neurotransmitter of the central nervous system.

Now, the research team, led by Gotz, has taken a closer look at this brain region in the mouse model. They found that even in the forebrain, there are other nerve cells that are regularly generated – the so-called glutamatergic nerve cells, which use glutamate as neurotransmitter.

Rest of article here.

Play brain games to generate neurons at Myfitbrain.

Bad drivers may in part have their genes to blame, suggests a new study by UC Irvine neuroscientists.

People with a particular gene variant performed more than 20 percent worse on a driving test than people without it – and a follow-up test a few days later yielded similar results. About 30 percent of Americans have the variant.

“These people make more errors from the get-go, and they forget more of what they learned after time away,” says Dr. Steven Cramer, neurology associate professor and senior author of the study published recently in the journal Cerebral Cortex.

This gene variant limits the availability of a protein called brain-derived neurotrophic factor during activity. BDNF keeps memory strong by supporting communication among brain cells and keeping them functioning optimally. When a person is engaged in a particular task, BDNF is secreted in the brain area connected with that activity to help the body respond.

Previous studies have shown that in people with the variant, a smaller portion of the brain is stimulated when doing a task than in those with a normal BDNF gene. People with the variant also don’t recover as well after a stroke. Given these differences, the UCI scientists wondered: Could the variant affect an activity such as driving?

“We wanted to study motor behavior, something more complex than finger-tapping,” says Stephanie McHughen, graduate student and lead author of the study. “Driving seemed like a good choice because it has a learning curve and it’s something most people know how to do.”

The driving test was taken by 29 people – 22 without the gene variant and seven with it. They were asked to drive 15 laps on a simulator that required them to learn the nuances of a track programmed to have difficult curves and turns. Researchers recorded how well they stayed on the course over time. Four days later, the test was repeated.

Results showed that people with the variant did worse on both tests than the other participants, and they remembered less the second time. “Behavior derives from dozens and dozens of neurophysiologic events, so it’s somewhat surprising this exercise bore fruit,” Cramer says.

The gene variant isn’t always bad, though. Studies have found that people with it maintain their usual mental sharpness longer than those without it when neurodegenerative diseases such as Parkinson’s, Huntington’s and multiple sclerosis are present.

“It’s as if nature is trying to determine the best approach,” Cramer says. “If you want to learn a new skill or have had a stroke and need to regenerate brain cells, there’s evidence that having the variant is not good. But if you’ve got a disease that affects cognitive function, there’s evidence it can act in your favor. The variant brings a different balance between flexibility and stability.”

A test to determine whether someone has the gene variant is not commercially available.

“I’d be curious to know the genetics of people who get into car crashes,” Cramer says. “I wonder if the accident rate is higher for drivers with the variant.”

In addition to Cramer and McHughen, Paul Rodriguez, Laura Marchal-Crespo and Vincent Procaccio of UCI worked on the study, along with researchers from the University of Florida. The National Institutes of Health funded the study.