Scientists Predict How Alzheimer’s Will Progress

Researchers have developed models to predict cognitive decline in patients with Alzheimer’s disease.

More than 6 million Americans are estimated to have Alzheimer’s disease, the most common type of dementia. The condition is defined by cognitive decline, the rate of which varies greatly from person to person.

The authors of the new study published in Neurology developed models to predict patients’ scores decline on a test of thinking and memory skills. Then, they compared the models to data from actual Alzheimer’s patients over time.

The study included 961 people with an average age of 65. Of those, 310 had mild cognitive impairment, and 651 already had mild dementia. All patients had the amyloid-beta plaques in their brains — the hallmark of Alzheimer’s disease — that are targeted by the new drugs.

The participants underwent a cognitive test, the scores of which ranged from zero to 30. Scores of 25 and higher indicate no dementia, scores of 21 to 24 indicate mild dementia, scores of 10 to 20 indicate moderate dementia, and scores lower than 10 indicate severe dementia.

In patients with mild cognitive impairment, the test scores declined from 26.4 at the beginning of the study to 21.0 five years later. The scores of people with mild dementia declined from 22.4 to 7.8 five years later.

The actual test score slightly differed from the predicted score. For half of patients with mild cognitive impairment, the difference was less than two points, and less than three points for half of patients with mild dementia.

The researchers determined that a hypothetical person with mild cognitive impairment, a baseline test score of 28, and a certain level of amyloid plaques would be predicted to reach the stage of moderate dementia after six years. If they received treatment with drugs reducing the rate of decline by 30%, they would not reach the stage of moderate dementia until after 8.6 years.

The model predicted that a hypothetical person with mild dementia, a baseline score of 21, and a certain level of amyloid would reach a score of 15 points in 2.3 years. If they were taking the medication, it would take 3.3 years.

However, the study findings should be interpreted with caution, as the cognitive tests were not always given at the same time of day. People with cognitive decline may score lower later in the day when they are more tired.

Researchers hope that the models could help people with cognitive problems and their care partners to predict how long they will be able to drive a car or keep doing their hobby.