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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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