US researchers have developed a new tool that assesses 15 risk factors for dementia that can predict whether people aged 65 and over have a high risk of developing Alzheimer’s.

The study was the work of first and corresponding author Dr Deborah Barnes of the Department of Psychiatry at the University of California, San Francisco, and colleagues, and was published online on 13 May in the journal Neurology. Barnes also works at the San Francisco Veterans Affairs Medical Center and is a member of the American Academy of Neurology.

Scoring 8 or more points on the 15-point scale indicates that a person is at high risk of developing dementia in the next six years, said the researchers in a press statement.

Many of the scale items are well-known risk factors for Alzheimer’s disease. These include: older age, having a gene that has been linked to the disease, and getting low scores on tests of thinking skills.

Barnes and colleagues were suprised however by some of the other factors that predicted dementia.

For instance, having had coronary bypass surgery, being underweight, not drinking alcohol, or being slow at physical tasks such as buttoning a garment, also predicted higher risk of developing dementia compared to not having these risk factors.

Barnes said:

“This new risk index could be very important both for research and for people at risk of developing dementia and their families.”

“It could be used to identify people at high risk for dementia for studies on new drugs or prevention methods,” she added.

It could also help to identify people who show no signs of dementia yet but who should be monitored more closely so that treatment can start sooner rather than later, and perhaps help them keep their thinking and memory skills and quality of life longer, explained Barnes.

She and her colleagues developed the index by following 3,375 people taking part in the Cardiovascular Health Cognition Study who had an average age of 76 and had no symptoms of dementia at the start of the study which went on for six years. 59 per cent were women and 15 per cent were Afirican American.

Over the six years of the study, 480 participants (14 per cent) developed dementia. The researchers used a statistical method called logistical regression analysis to identify the cluster of risk factors assessed in the examinations that most closely linked with cases of dementia. They created the 15-point index from these factors.

The results showed that 56 per cent of the participants with high scores on the risk index developed dementia, compared with 23 per cent who only had moderate scores and 4 per cent who had low scores. Overall, the risk index correctly classified 88 per cent of the participants, said the researchers.

The next stage is to make the index more robust by validating it with other studies, said Barnes, who with her colleagues is hoping to create a shorter, simpler version that is just as accurate.

The Cardiovascular Health Study is a longitudinal study of risk factors for cardiovascular disease among nearly 6,000 community-dwelling people aged 65 and over that included a large number of people who also underwent extensive neurological examinations for dementia and cognitive impairment.

“Predicting risk of dementia in older adults. The late-life dementia risk index.”
D. E. Barnes, K. E. Covinsky, R. A. Whitmer, L. H. Kuller, O. L. Lopez, and K. Yaffe
Neurology, first published online on May 13, 2009
doi:10.1212/WNL.0b013e3181a81636

Additional sources: American Academy of Neurology.

Written by: Catharine Paddock, PhD