Expert: Mary Gordon - 4/19/2007

Question
My grandfather served in WWII as a navigator and for 17 years thereafter. He is now suffering from Alzheimer's Disease. I have heard that there is a correlation between the two. Is this true? If so, where can I get informaiton on it for a research paper I am preparing? Thank you very much.

Answer
Well, I can't do your homework for you, but I have to tell you, the idea that being a navigator causes Alzheimer's is a new one on me. I've never seen anything solid that suggests aviation as an occupation might cause Alzheimer's. If your grandfather was in WWII, he has to be over 80, and the biggest risk factor for Alzheimer's is....age. The longer you live, the higher your odds. Countries whose populations are very healthy and live the longest are also the countries with the highest rates of Alzheimers. From age 65-74, about 3% of people have AD. From 75-84, its 19% and for those 85 and older its 47% odds, irrespective of what anyone did for a living in their younger days (and the highest occupational group would be...housewives, since women tend to live longer than men, and the odds are very good that a lady in her 80s today was a homemaker).

The next biggie is family history. If you have a first degree relative with Alzheimer's (i.e. parent, sibling, or child) your odds are somewhat higher. When diseases tend to run in families, either heredity (genetics) or environmental factors or both may play a role.   

There is one marker gene associated with a higher risk of Alzheimer's called APOE-e4. It is one of is one of three common forms of the APOE gene - everyone has two copies of some form of APOE gene. APOE provides the blueprint for one of the proteins that carries cholesterol in the bloodstream. You can inherit one or two copies of APOE-e4. Although it raises your odds, even people with 2 copies of APOE-e4 don't always develop AD.

People with Down's syndrome almost always develop a form of Alzheimer's if they live into middle age. There are also families where a really nasty, early onset form of AD runs - if you were a member of one of those families you would know about it - it is strongly inheritable - 50:50, so similar to Huntington's Disease. Only 1% of cases are known to fall into that category.

A history of head injury also ups your odds of AD. Diseases that damage blood vessels like high blood pressure, heart disease, stroke, diabetes and high cholesterol up your odds - although, I strongly suspect those factors up your odds of multi-infarct dementia (the second most common cause of
AD, caused by teeny strokes). Doctors aren't always very careful when they diagnose AD, so many causes of what is diagnosed as AD are actually multi-infarct dementia.

There have been several occupational studies and none of them were able to conclude with any certainty that exposure to various things in the work place caused cognitive issues later in life - which is probably because its the healthy ones who live long enough to develop AD.  

Collectively the best way to control risk is to do what the doctor tells you. Eat well, exercise, take good care of yourself, keep your blood pressure and weight down, don't smoke, don't drink too much.

I googled occupational factors every which way, and found nothing about exposure to the kind of environment a navigator would be in around planes, hangars, the tarmack (such as solvents, fuels etc.) -  that suggested that would have upped his odds.

Mary G.