Neurologist Discusses Alzheimer's

Personally, I would consider getting genetic testing if I had a family history of very frequent dementia occurring at a young age (30s, 40s, early 50s) in several generations of my family. These families are relatively rare (less than 3 percent of all Alzheimer's cases), but they are the most likely to have a genetic etiology. If the mutation is known for the family, genetic testing would give a fairly definitive answer about whether I would be a victim of early Alzheimer's disease like my family members. Before getting the test, I would have considerable genetic pre-counseling. Our experience with people at risk for Huntington's disease (an inherited cause of dementia and movement problems) has shown that many people at risk decide not to take genetic tests once they have completed educational counseling.

If Alzheimer's is present in a first-degree family member (parents, siblings and children), but occurred at older ages, there is unlikely to be a marker relevant to your increased genetic risk other than your Apolipoprotein E(ApoE) genotype. ApoE is a normal ipoprotein that transports cholesterol in the body. Similar to blood type (ie, type A, B, and O), ApoE comes in 3 genetic types: e2, e3, and e4. Everyone has two alleles (one from each parent). The most common combination in more than half of the population is to have e3/3. People with one or more ApoE -e4 alleles are at higher risk of developing Alzheimer's at an earlier age. However, ApoE genotype provides very little information on an individual level. More than half of the people who develop Alzheimer's disease do not have an e4 allele, so having a 'negative' test should not be overly reassuring. Moreover, we have encountered people in their 90's with APOE e4/4 genotype(two e4 alleles carry the highest risk for Alzheimer's), but even in advanced age, these individuals continue to have normal cognition. Thus, even having two alleles doesn't necessarily doom you to the disease. Therefore, we are really unable to tell individuals who are concerned with their risk specifics as to when and if Alzheimer's will strike. Furthermore, there is no specific medical benefit in knowing your genetic predisposition before the onset of symptoms at this time. Hopefully, continued research will provide better understanding of the disease and eventually lead us to better diagnostic and treatment options so knowing your risk early could mean taking preventative measures.

Preventative measures for Alzheimer's are actively under study for people with and without family histories. There are no specific measures that have been clearly shown to be able to prevent Alzheimer's disease. However, observational studies have suggested that factors associated with "a healthy lifestyle" may also be good for brain health. These factors include exercise, high levels of social engagement, and a well-balanced, low-fat diet that includes a variety of vegetables, fruits and omega acids (fish).