Is it Possible to Predict How Quickly Cognitive Decline Occurs in Early Alzheimer’s Disease?

A new study looks at predicting how quickly the cognitive abilities of people with early Alzheimer’s disease will decline. The study is published in the July 10, 2024 online issue of Neurology®, the medical journal of the American Academy of Neurology. It also looked at how the new drugs recently approved for the disease can reduce decline. The rate of cognitive decline varies greatly from person to person, and people are very interested in what to expect from the disease in themselves or their loved ones. Therefore, better predictive models are urgently needed.

Model Helps Predict Speed of Cognitive Decline

The researchers, led by study author Pieter J. van der Veere, M.D., of the Amsterdam University Medical Center, Netherlands, developed models to predict how quickly people’s scores on a test of thinking and memory skills would deteriorate. They then compared the models with people’s actual scores over time. They studied 961 people with an average age of 65 – 310 had mild cognitive impairment and 651 had mild dementia. All had amyloid beta plaques in the brain, which are an early sign of Alzheimer’s disease and are targeted by the new drugs.

On the cognitive test, scores range from zero to 30, with scores of 25 and above indicating no dementia, scores of 21 to 24 indicating mild dementia, scores of 10 to 20 indicating moderate dementia and scores below 10 indicating severe dementia. The test scores of people with mild cognitive impairment fell from 26.4 at the start of the study to 21.0 five years later. The scores of people with mild dementia fell from 22.4 to 7.8 five years later.

The models were helpful in predicting the rate of cognitive decline, but also show the uncertainty of these predictions, van der Veere noted. In half of the people with mild cognitive impairment, the actual test result differed from the predicted result by less than two points. For those with mild dementia, the results differed by less than three points for half of the individuals.

The researchers found that a hypothetical person with mild cognitive impairment, a baseline score of 28 and a certain level of amyloid plaques would be expected to reach the stage of moderate dementia (test score of 20 points) after six years. If drug treatment were to reduce the rate of deterioration by 30%, this person would only reach the stage of moderate dementia after 8.6 years. For a hypothetical person with mild dementia, a baseline score of 21 and a specific amyloid concentration, the predicted time to reach a score of 15 points was 2.3 years, or 3.3 years if deterioration was reduced by 30%. The researchers hope that in the future, models will help make predictions about these quality of life and daily functioning issues. But until then, they hope these models will help doctors translate these predictions into answers to people’s questions.

One limitation of the study was that the cognitive tests were not always conducted at the same time of day, and people with cognitive impairment may perform worse later in the day when they are more tired.

Pay Attention to Heart Health

People at higher risk for cardiovascular disease show increased cognitive decline, including an increase in typical markers of Alzheimer’s disease, suggesting that monitoring and controlling heart disease may be key to maintaining and improving cognitive health later in life, according to a study published in the Journal of the American College of Cardiology.

In fact, researchers found that a higher cardiovascular risk burden was associated with a faster decline in episodic memory, working memory and perceptual speed. The researchers also examined MRI data from a subset of patients and found that higher FGCRS was associated with lower hippocampal, cortical gray matter and whole brain volume. Reductions in the hippocampus and gray matter are typical signs of neurodegeneration associated with Alzheimer’s dementia. The MRI images also showed a greater volume of white matter hyperintensities, which are white patches in the brain that lead to a decrease in the functionality of an area.