Alzheimer’s may be predicted 18 years in advance through memory, thinking tests

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Alzheimer’s can possibly be predicted based on errors on memory and thinking tests up to 18 years before the disease can be diagnosed, a new research has suggested.

According to Kumar B. Rajan, PhD, with Rush University Medical Center in Chicago, who is also the lead author of the study, suggests that the changes in thinking and memory that precede obvious symptoms of Alzheimer’s disease begin decades before.

Rajan added that though it isn’t possible to detect such changes in individuals who might be at risk, they were able to observe those individuals among a group who eventually developed dementia due to Alzheimer’s.

For the study, 2,125 European-American and African-American people from Chicago with an average age of 73 without Alzheimer’s disease were given tests of memory and thinking skills every three years for 18 years.

Twenty-three per cent of African-Americans and 17 per cent of European-Americans developed Alzheimer’s disease during the study. Those who scored lower overall on the memory and thinking tests had an increased risk of developing the disease.

During the first year of the study, people with lower test scores were about 10 times more likely to be diagnosed with Alzheimer’s disease than people with higher scores, with the odds increasing by 10 for every standard deviation that the score was lower than the average.

Based on tests completed 13 to 18 years before the final assessments took place, one unit lower in performance of the standardized cognitive test score was associated with an 85 percent greater risk (relative risk of 1.85) of future dementia. “While that risk is lower than the same one unit lower performance when measured in the year before dementia assessment, the observation that lower test scores 13 to 18 years later indicates how subtle declines in cognitive function affect future risk,” said Rajan.

“A general current concept is that in development of Alzheimer’s disease, certain physical and biologic changes precede memory and thinking impairment. If this is so, then these underlying processes may have a very long duration. Efforts to successfully prevent the disease may well require a better understanding of these processes near middle age,” Rajan said.

The research is published in journal Neurology.