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Wednesday, 5 February, 2003, 06:27 GMT
Brain 'compensates' for Alzheimer's
Brain image
The brain has reserves it can draw on
The brains of people in the early stages of Alzheimer's compensate for damage done by the disease, researchers have found.

In memory tests, they appear to draw on a particular part of the brain not normally associated with this function.

Researchers say the ability of the brain to compensate for the damage done by Alzheimer's does diminish as the disease progresses.

But they say the discovery could point towards treatments which could maintain the compensatory effect.

What that means in real life I'm not sure

Dr Richard Harvey, Alzheimer's Society
However, UK experts cast doubt on whether the discovery could advance treatment for Alzheimer's disease.

Alzheimer's is an incurable degenerative brain disorder that causes intellectual impairment, disorientation and eventually death.

People in the early stages of the disease experience problems with their episodic memory - of events in their life, such as graduating or a trip to the dentist - and semantic memory, general knowledge such as the names of people or places and major historical events.


Researchers from the Rotman Research Institute at Baycrest Centre for Geriatric Care, in Toronto, Canada compared 12 healthy elderly people with 11 thought to be in the early stages of Alzheimer's.

Each was given quick-fire memory tests on a computer.

In the test of their semantic memory, a word or object appeared on one side of the screen, and a visual noise pattern appeared on the other.

They were asked to decide whether or not the object was living.

The episodic recognition task involved patients being shown two objects or words on screen at the same time, one of which they had seen in the previous task.

They were asked to select which object or word they had seen before.

Brain activity was monitored using positron emission tomography (PET), which measures blood flow to various regions of the brain.

Overall, Alzheimer's patients performed less well in each test.

But some did better than others.


Researchers found that those who did better had more activity in the prefrontal network area of the brain than those who made more errors.

None of the healthy patients showed this pattern of brain activity.

Dr Cheryl Grady, who led the research, said: "We found that patients who were able to recruit the prefrontal cortex of the brain 'to a greater degree' than other patients, performed more accurately on memory tests.

She added: "The development of compensatory responses in relation to early cognitive changes in Alzheimer's is an area in need of more investigation.

"The goal, until more definitive preventive treatment is found, is to develop more effective treatments that extend this compensatory effect and delay the degenerative effects of Alzheimer's for longer periods."

Real life

Dr Richard Harvey, head of research for the UK Alzheimer's Society: "This shows that some people with Alzheimer's who have specific tests are able to learn better than others.

"But what that means in real life, I'm not sure.

"We already know that the brain does compensate when there's a problem."

Dr Harvey said there was a large part of the brain which people did not use in everyday life - the cerebral reserve.

But he added: "As far as I can see, there is no way this research could be developed into treatment."

The research is published in the Journal of Neuroscience.

See also:

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