Can a saliva test really detect your genetic “risk” of Alzheimer’s?

Unlocking the data stored within our DNA can help us learn a host of different things about our ancestry and health. But how much should you worry if your genes are linked to the development of disease?

23andMe, a genetic testing company, aims to arm people with foreshadowing about their health risks. It recently received Food and Drug Administration (FDA) permission to sell individualized genetic risk reports directly to consumers.

The most prominent among the diseases and conditions tested are late-onset Alzheimer’s, Parkinson’s and celiac disease. 23andMe uses a saliva sample to seek out specific genetic variants in a customer’s DNA that are associated with increased lifetime risk of 10 maladies. The report sells for $179 and includes information on ancestry, genetic traits and whether a customer is a carrier for specific diseases.

Considering Factors

If you decide to buy the test, there are some issues to consider:

• Having a genetic variant does not mean you are likely to get the disease. Many conditions have a very small average lifetime percentage risk, and an enhanced risk likely will still be small.
• Not having a genetic variant does not mean you won’t get the disease. Genes are one piece of a larger disease-risk puzzle. Lifestyle and family history arguably are at least as influential. The 23andMe genetic test does not factor in family history. The FDA carefully pointed out the tests “are intended to provide genetic risk information to consumers,” and they “cannot determine a person’s overall risk of developing a disease or condition.”
• Get help in figuring out what the test results mean. It’s not wise to make life choices based only on a genetic test. The Alzheimer’s Association encourages people to consult a genetic counselor before and after undergoing genetic testing.

The test results can be jarring emotionally if you don’t know how to interpret them. 23andMe requires consumers read an online disclaimer before they can view their results for Alzheimer’s and Parkinson’s.

Claudia R. Padilla, MD, medical director of the Baylor AT&T Memory Center, is developing a research program focused on new medications and treatments for Alzheimer’s disease and other dementias.

Dr. Padilla is asked by patients about the genetic risk of developing Alzheimer’s. She encourages people to talk to their physician and a genetic counselor before genetic testing to understand the meaning of the genes.

The board-certified behavioral neurologist points out there are two categories of genes. Risk genes increase the likelihood of developing a disease but do not guarantee it will happen. Deterministic genes directly cause a disease, guaranteeing that anyone who inherits one will develop the condition. ApoE4, the Alzheimer’s disease gene that 23andMe tests for, is a risk gene. The American College of Medical Genetics does not recommend testing for that gene.

Dr. Padilla counsels her patients to remain socially, physically and mentally active to combat Alzheimer’s risk. She also recommends the MIND diet, a hybrid of the Mediterranean and DASH diets that emphasize brain-healthy foods such as vegetables, nuts, berries, beans, fish, poultry and olive oil.

Learn more about Alzheimer’s genetic testing, here.