Can Genetic Risk for Alzheimer's be Reduced?

Contributed by: Dennis Fortier, President, Medical Care Corporation

As genetic testing has become more commonplace in medicine, we have all seen frequent examples of overstatement, where writers and speakers confuse "higher risk" with "absolute certainty".  This has been an especially maddening component of arguments against testing for the APOe4 gene associated with increased risk for Alzheimer's disease.

A great many of these faulty arguments state that learning about a genetic risk for an incurable disease is pointless.  (I have refuted that argument many times but that is not the point of this post).  This week, research published in Archives of Neurology strengthens the case for genetic testing.

In a study from the University of Washington in St. Louis, more than 200 participants aged 45 to 88 reported on their physical exercise habits and submitted to spinal fluid measures or PET scans to determine the amount of accumulated amyloid protein in their brains. They also had their APOe4 status checked and researchers found that, among those who carried the APOe4 gene, regular exercisers had less amyloid load than sedentary members of the group.  Interestingly, this was not the case among the APOe4 non-carriers.

This was a small study and needs replication before we can conclude that physical exercise staves off amyloid accumulation in those with genetic risks for AD.  However, the study has a very intuitive finding and gives credence to a much larger body of work showing that good cardiovascular health may reduce the risk of Alzheimer's disease.

The suggestion from this study is very significant.  It could be that genetic risk for AD (usually considered to be an unmodifiable risk), could possibly be reduced by physical exercise.  If so, it will put a whole new spin on those old arguments against genetic testing.

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