Brain may 'work around' early Alzheimer's damage

Date: Sep-15-2014One of the hallmarks of Alzheimer's disease - the most common form of dementia - is the

build-up of beta-amyloid protein deposits in the brain. Now a new study published in the

journal Nature Neuroscience suggests that in some older people, the brain has a way of

compensating for this damage by recruiting extra brain circuits.

Previous studies of scans have shown that some older adults with Alzheimer's damage who retain

thinking and memory capacity show signs of extra brain activation.

But until this study, it was not clear whether this extra activation is linked to better

mental performance or if the extra activation is abnormal over-excitement.

William Jagust, a professor in Public Health and Neuroscience at the University of California, Berkeley, says they found

the aging brain can compensate for beta-amyloid damage.

He says it is still not clear, though, why some older people with beta-amyloid deposits are

better at using different parts of their brain than others.

Stimulating mental activity may help brain remain adaptable to damage

However, in a previous study, he and his colleagues found that lifelong active brains have less

Alzheimer's protein, so he suggests:

"I think it's very possible that people who spend a lifetime involved in cognitively

stimulating activity have brains that are better able to adapt to potential damage."

Alzheimer's disease accounts for 60-80% of cases of dementia, a general term for conditions

that impair memory and mental ability so much that daily life becomes very difficult.

According to the Alzheimer's Association, every 67 seconds, someone in the

United States develops the disease. The direct cost to the nation of caring for people with

Alzheimer's will total an estimated $214 billion in 2014, including $150 billion in costs to

Medicare and Medicaid.

Alzheimer's disease has two hallmarks: deposits of beta-amyloid protein that build up in the

spaces between nerve cells, and tangles or twisted fibers of another protein called tau that

build up inside cells.

Evidence that the aging brain can compensate for presence of Alzheimeir's proteins

For their study, Prof. Jagust and colleagues examined functional magnetic resonance imaging brain scans of 71 participants as

they performed mental tasks. The participants were 22 healthy young adults and 49 older adults

with no signs of mental decline.

Shown are scans that represent all subjects with beta-amyloid deposits in their brain. The yellow and orange colors show areas where greater brain activation was associated with the formation of more detailed memories.
Image credit: Jagust Lab

The brain scans revealed 16 of the older participants had beta-amyloid deposits, and the

others did not.

For the mental tasks, the researchers asked the participants to memorize pictures of various

scenes. Afterwards, they tested their ability to remember the gist, and then the details, of

what they had seen.

For example, one of the pictures showed a boy doing a handstand. To recall the gist,

participants were asked whether a general description of a boy doing a handstand corresponded to

the picture. Then they were asked to confirm whether more specific details - such as the color

of the boy's shirt - were correct.

Prof. Jagust says both the groups performed the tasks equally well, but "it turned out that

for people with beta-amyloid deposits in the brain, the more detailed and complex their memory,

the more brain activity there was."

"It seems that their brain has found a way to compensate for the presence of the proteins

associated with Alzheimer's," he adds.

Funds from the National Institute on Aging and the McKnight Foundation helped finance the

study.

Recently, a team led by Washington University in St. Louis, MO, suggested that
late and early onset Alzheimer's are similar in the way they affect brain function.

Written by Catharine Paddock PhD

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Courtesy: Medical News Today Note: Any medical information available in this news section is not intended as a substitute for informed medical advice and you should not take any action before consulting with a health care professional.