Some people who have a parent or another close relative with early-onset Alzheimer’s disease opt to undergo genetic testing to determine whether they’re at high risk for the disease.
Is Alzheimer’s Genetic?
Early-onset Alzheimer’s disease (also known as “familial Alzheimer’s disease”) is a rare, inherited form of Alzheimer’s that develops before 65 years of age. Early-onset Alzheimer’s shows a strong pattern of inheritance. A child who has one parent with the disease has a 50 percent chance of developing it as well. If both parents have the disease, the risk to the child will be even greater.
Late-onset Alzheimer’s disease (or “sporadic Alzheimer’s disease”) develops after the age of 65. Researchers have identified a certain inherited gene mutation associated with late-onset Alzheimer’s, but heredity appears to be just one of a number of risk factors for the disease–it’s not a sole cause. An individual with this gene mutation may never actually develop Alzheimer’s disease.
Finding out if You Have Alzheimer’s: Genetic Testing
Genetic testing is a process by which a geneticist examines your DNA to determine whether it contains genetic alterations that indicate disease susceptibility, certain characteristics and tendencies, or family history. Alzheimer’s genetic testing can confirm an Alzheimer’s diagnosis or alert your doctor that you may be at risk of developing the disease in the future.
A positive result indicates that the genetic alteration for which you were tested is present in your DNA. This information can be very useful as it can forewarn you that you need to make certain lifestyle changes to reduce your risk of developing Alzheimer’s disease. However, a positive result does not necessarily mean you will develop the disease. Similarly, a negative result doesn’t necessarily mean that you won’t ever develop Alzheimer’s disease. The results simply indicate susceptibility.
Genetic testing is not a reliable indicator for late-onset or sporadic Alzheimer’s disease. This is because late-onset and sporadic Alzheimer’s are affected by so many other risk factors, such as:
- Low levels of physical and mental activity
- Medical conditions (i.e. high blood pressure)
- Poor diet.
Genetic testing for early-onset Alzheimer’s disease is much more reliable.
Speak with your doctor or a genetic counselor before you decide to undergo Alzheimer’s genetic testing. She will be able to point out the pros and cons of genetic testing, as well as help you navigate the number of psychological, legal and social issues that you may not have considered. She will also discuss with you the potential implications of your test results and help you decide on an appropriate course of action to take.
Alzheimer’s Association. (n.d.) Genetic testing. Retrieved June 9, 2010, from http://www.alz.org/national/documents/topicsheet_genetictesting.pdf.
Alzheimer Society of Canada. (n.d.) Alzheimer’s disease and genetics: The role of genes in Alzheimer’s disease. Retrieved April 24, 2010, from http://www.alzheimer.ca/english/disease/causes-heredity.htm.
Fisher Center for Alzheimer’s Research Foundation. (2004). Good genes, bad genes: The pros and cons of Alzheimer’s screening. Retrieved June 9, 2010, from http://www.alzinfo.org/newsarticle/templates/archivenewstemplate.asp?articleid=151