Ask an Arkansas Expert Library

My grandmother developed Alzheimer’s disease in her 80s. Am I at risk?

Because of its prevalence we should all consider ourselves at risk of Alzheimer’s disease. Among those over the age of 65, about 10% have Alzheimer’s or a similar disorder; among those over 85, the number goes up to around 40%! For a small fraction of cases — probably about 8% — the disease is strictly genetic. This means that the children of these persons have a 50-50 chance of getting it, and their grandchildren have a 25% chance. These cases are usually distinguished by their young age of onset. If your grandmother developed Alzheimer’s after the age of 65, the odds are that hers was not one of these strictly inherited cases.

However, just as our genes influence our chances of developing cancer, heart disease, or even alcoholism, numerous genes make a fractional contribution to our risk for Alzheimer’s disease. In other words, one gene may make you 50% more likely to get the disease than your neighbor; another gene may make your risk twice as high. Together, the combined increase in your risk would mean you are about two and a half times as likely to develop Alzheimer’s disease than your neighbor. Identifying these genes and how they might work together with one another or with aspects of one's environment is an active area of research.

Steven W. Barger

Return to list of questions