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Posts Tagged ‘Brain’

The Case Of The Shrinking Brain

It was believed that a significant amount shrinkage was inevitable as a healthy brain aged, as though aging should be the mental equivalent of taking a cold shower. As it turns out, that belief is wrong.

Previous studies of the brain in older people may have inadvertently included individuals going through the early stages of dementia. The results of a long term study were recently revealed in the September issue of Neuropsychology (an APA publication).

After examining behavioral data collected from 1994 to 2005 (with scans taken between 1997 and 1999 depending on when people entered the study), the researchers divided participants into two groups: one group with 35 cognitively healthy people who stayed free of dementia (average starting age 69.1 years), and the other group with 30 people who showed substantial cognitive decline but were still dementia-free (average starting age 69.2 years).

By dividing the people into separate groups the researchers were able to determine that a reduction in brain volume as we age should not be considered the norm. Rather, it is a sign of dementia.

In contrast to the 35 people who stayed healthy, the 30 people who declined cognitively over nine years showed a significant effect for age in the hippocampus and parahippocampal areas, and in the frontal and cingulate cortices. In short, among the people whose cognition got worse, older participants had smaller brain areas than younger participants.

Thus, the seeming age-related atrophy in gray matter more likely reflected pathological changes in the brain that underlie significant cognitive decline than aging itself, the authors wrote. As long as people stay cognitively healthy, the researchers believe that the gray matter of areas supporting cognition might not shrink much at all. “If future longitudinal studies find similar results, our conception of ‘normal’ brain aging may become more optimistic,” said lead author Saartje Burgmans, who is due to receive her PhD later this year.

As we pass certain age milestones, the odds of having dementia get higher. A study published in Neurology (the medical journal of the American Academy of Neurology) noticed something strange in the statistics for individuals above the age of 90. Women are 45% likely to suffer from dementia, whereas for men it is a much lower 28% likelihood.

Research has shown that dementia prevalence for both men and women increases from age 65 to 85. The frequency of dementia increases with age from less than 2 percent for the 65-69-year-olds, to 5 percent for the 75-79-year-olds and to more than 20 percent for the 85-89-year-olds.

The UC Irvine study, conducted in Laguna Woods, Calif., is among the few to look at dementia in people over age 90. It found that the likelihood of having dementia doubled every five years in women after reaching 90, but not in men. The results also showed that women with a higher education appeared to be as much as 45 percent less likely to have dementia compared to women with less education.

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Use It Or Lose It

Putting your brain to use through years of formal education can serve as a protector against the effects of Alzheimer’s disease. The remarkable effect discovered was not that years of education lower the odds of getting the disease. Instead, researchers discovered that those individuals with more formal education were not showing clinical symptoms of brain deficits compared to other people with Alzheimer’s and without the educational background.

These phenomena are often ascribed to the theoretical concept of cognitive reserve. A high level of cognitive reserve results in a strong individual resilience against symptoms of brain damage; cognitive reserve can therefore be seen as protective against brain damage.

The amount of brain tissue lost was assessed through MRI (Magnetic Resonance Imaging) scans. Somehow, those with the benefit of a formal education showed an equal amount of brain volume lost, yet they were able to function normally.

Human brains are flexible organs, and it’s never too late to give them a workout. Although this study, published in the current issue of the Journal of Alzheimer’s Disease (“Education attenuates the effect of medial temporal lobe atrophy on cognitive function in Alzheimer’s disease: The MIRAGE Study,” Journal of Alzheimer’s Disease, August 2009), used formal education as a convenient guideline, you can get similar benefits by exercising your brain regularly with mentally challenging activities.

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The old hypothesis regarding appetite control and the body was that the hormone leptin regulated satiety. If the body produced more leptin, appetite would be suppressed by sending a signal to a particular part of the brain called the ARC (arcuate nucleus). ARC is in an area of the hypothalamus that controls energy balance.

However, new research shows that other parts of the brain have receptors for leptin. The LHA (lateral hypothalamic) area is one such example, and it has strong connections to the dopamine system in the VTA (ventral tegmental area) which is responsible for the brain’s reward system. Dopamine is the chemical signal used by the brain for rewards.

The new hypothesis shows that someone who has a higher amount of dopamine under normal circumstances may be more resistant to food temptations. Also, someone with naturally low levels of leptin may eat more to stimulate the reward system to bring dopamine levels to what feels “normal”.

The new study shows that leptin injected in the LHAs of rats causes the animals to eat less and lose weight. Leptin action in the LHA also raises dopamine content in the brains of otherwise leptin-deficient animals.

We are moving closer to a day when an eating disorder can be dealt with by simply taking a pill. However, it will take several years and more studies like this one before a product is commercially available.

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After ingestion, alcohol gets to the brain how quickly?

Only six minutes after consuming an amount of alcohol equivalent to three glasses of beer or two glasses of wine, leading to a blood alcohol level of 0.05 to 0.06 percent, changes have already taken place in the brain cells, as the scientists in Heidelberg proved using magnetic resonance spectroscopy (MRS).

Well, now we have confirmation on the timeless classic “candy is dandy, but liquor is quicker”. What we are really concerned about are the effects of alcohol, not just the speed at which it does its magic.

Is all consumption of alcohol harmful for the brain? “Our follow-ups on the next day showed that the shifts in brain metabolites after moderate consumption of alcohol by healthy persons are completely reversible,” says Dr. Armin Biller. “However, we assume that the brain’s ability to recover from the effect of alcohol decreases or is eliminated as the consumption of alcohol increases. The acute effects demonstrated in our study could possibly form the basis for the permanent brain damage that is known to occur in alcoholics.

In conclusion, drinking a bit is fine, drinking to excess has long term negative consequences. We have a ton of respect for those German researchers who have bravely discovered how to get the university budget to cover their bar tab.

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