Seniors' Health: Simple index warns of dementia risk

Doctors may soon be able to predict an elderly person's risk of developing dementia with nearly 90 per cent accuracy, simply by using information that can be collected at the bedside or in the office.

"There are lots of tools that doctors currently use to predict risk of various diseases. Probably the most famous one is the Framingham Index, which is used to predict someone's risk of having a heart attack," says Deborah Barnes, a researcher at the San Francisco Veterans Affairs Medical Center. "The idea behind the study was to try to develop something similar for dementia."

Barnes and her colleagues developed two indices. The first was a long index that was as detailed as possible and included results from brain scans and genetic tests. The second index was designed for use in a doctor's office, and used only easily accessible information such as age, medical history and scores on two simple mental tests.

The indices were tested in 3,375 people with an average age of 76 years who did not initially have dementia. Over the next six years, 14 per cent of the participants developed dementia. Risk factors included age older than 70, a body mass index of less than 18, previous heart bypass surgery, slow physical function on everyday tasks, and low scores on the mental tests.

The long, comprehensive index was 88 per cent accurate in predicting dementia over the six-year period, and the short index was 87 per cent accurate.

"Perhaps there are certain situations in which a doctor would really want to have that extra bit of accuracy. But just for a busy clinical practice, we think probably that the shorter index is going to be something that people could hopefully use more routinely," Barnes says.

The index is not yet available for use, but Barnes and her team hope to make it available before the end of the year. "We're still validating it, and we'd particularly like to validate it in other study populations, such as in Canada, to make sure that it generalizes across different groups of people."

Once available, the index could be used to identify which people should be watched closely for changes in mental function. It could also be used to reassure or counsel people who wish to know their dementia risks. "As drugs are made available, or as different preventive strategies are made available, those could be targeted at the people who are higher-risk," Barnes says. "The high-risk people could also start having discussions with family members about what type of care they might want in the future if they were to develop dementia."