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Do Brains Shrink As We Age?

2009-09-16 04:55:50

Rachael Rettner

LiveScience Staff

LiveScience.com rachael Rettner

livescience Staff

livescience.com Tue Sep 15, 10:35 am ET

As we get older, our brains get smaller, or at least that's what many

scientists believe. But a new study contradicts this assumption, concluding

that when older brains are "healthy" there is little brain deterioration, and

that only when people experience cognitive decline do their brains show

significant signs of shrinking.

The results suggest that many previous studies may have overestimated how much

our brains shrink as we age, possibly because they failed to exclude people who

were starting to develop brain diseases, such as dementia, that would lead to

brain decay, or atrophy.

"The main issue is that maybe healthy people do not have as much atrophy as we

always thought they had," said Saartje Burgmans, the lead author of the study

and a PhD candidate at Maastricht University in the Netherlands.

Burgmans and her colleagues wondered what would happen if they were able to

screen out all of the people with so-called "preclinical" cognitive diseases.

Using information collected for Holland's Maastricht Aging Study, the

researchers analyzed data from 65 "healthy" individuals who did not show signs

of dementia, Parkinson's disease or stroke and who were monitored for a period

of nine years. Participants were on average 69 years old at the study's start.

Every three years, participants completed neuropsychological tests, which were

designed to assess their cognition. They also underwent a brain MRI scan.

From the test results, the researchers divided the participants into two

groups: a "healthy" group of 35 people, who showed no loss of mental abilities,

and another group of 30 people who showed substantial cognitive decline, but

did not have dementia.

Then, they analyzed the brain scans, looking at the size of seven regions

associated with cognition. In the healthy group, age did not have a significant

effect on brain size. In the other group, there was a large effect in all seven

brain areas - older participants had significantly smaller brain areas than

younger ones.

"What we found is that when you exclude all those people [who] are suspicious

for preclinical disease, and you just look at the healthy people who don't have

any suspicious cognitive decline, then you see that there is a very small age

effect in this group," said Burgmans.

The researchers caution that their findings are only preliminary, and that they

need to be confirmed in a larger group of people. Also, future studies should

include brain scans of people over time, and not just one brain scan, as was

the case for this study.

But their results demonstrate that it is important for scientists studying the

aging brain to assess the cognition of their participants over a number of

years, the researchers say.

The study was published in the September issue of the journal Neuropsychology.