Many adults are at greater risk of developing Alzheimer's disease because of their family and genetic history. While one cannot change the genes and risks associated with them, it is possible to mitigate or slow the symptoms of Alzheimer's disease. Knowing what the risks are can be of benefit in the development of target prevention.

This just got easier.

A research team in California recently reported that a collection of genes can better predict who will develop Alzheimer’s disease (AD). It has long been acknowledged that having a genetic factor called APOE-e4 was a risk to developing AD.

Everyone has two copies of some form of APOE: APOE-e2, APOE-e3 or APOE-e4. Having APOE-e4 predisposes one to Alzheimer's disease. Having both copies of APOE-e4 presents a greater risk than having only one copy and the other copy being one of the other two forms.

The research team led by Chin Hong Tan, Ph.D., a postdoctoral scholar at University of California San Francisco, reported their findings related to the genetic risk factors better predicting AD in the September issue of Annals of Neurology. They found that testing for APOE-e4 in combination with other genes — what they called the polygenic hazard score (PHS) provides a predictive value of 85 to 95 percent compared to testing of APOE-e4, which has a much lower prediction of expression of symptoms.

The study evaluated data on 1,081 participants from the National Alzheimer's Coordinating Center who had not been diagnosed with dementia and found that the PHS was predictive of how long it would take before the participants began demonstrating Alzheimer's disease dementia. The researchers also could predict how rapid the cognitive decline would be.

This is good news since there is evidence that changes in lifestyle can slow down symptoms of AD. Many of the lifestyle factors that contribute to poor health also contribute to higher rates of AD. Those associated with a higher risk of AD include smoking, diabetes mellitus type 2, physical inactivity and overweight/obesity. Physical inactivity has been reported to have the highest risk at 22 percent, and smoking the next highest risk at 15.7 percent.

As these are all factors under individual control, these are risks that can be eliminated. There has been a decline in the incidence of AD, and this is already attributed to a general adoption of healthier lifestyles.

"Our findings have strong implications for disease stratification and secondary prevention trials in Alzheimer's, as well as direct-to-consumer genetic tests, some of which have recently received FDA clearance," said Anders Dale, Ph.D., a professor of neurosciences and radiology at University of San Diego and co-author of the study.

People should not need to have genetic testing to motivate them to adopt the lifestyle modifications that are already attributed to prevention of cognitive decline such as healthier diet, smoking cessation and exercise. These benefit not just the brain but the entire body heart, bones and muscles.

However, knowing of an even greater risk of dementia may be the greater motivating factor to toss the doughnuts and get off the sofa.