Alzheimer's Risk and The Family
Of all illness, perhaps it’s Alzheimer’s that people most fear – because of its devastating circumstances, the fact that nothing can be done to prevent it, and the possible genetic factor.
In an issue of the Harvard Men’s Health Watch, experts explore the issue of what it means for your children or siblings if you’re diagnosed with Alzheimer’s? What if a close relative develops the condition.
“People think that if their dad or aunt or uncle had Alzheimer’s disease, they are doomed. But, no, that’s not true,” says Dr. Gad Marshall, assistant professor of neurology at Harvard Medical School. “Even though family history adds to the overall risk, age still usually trumps it quite a bit. It means your risk is higher, but it’s not that much higher, if you consider the absolute numbers.”
According to the Harvard experts, “studies of family history say that if you have a close relative who has been diagnosed with Alzheimer’s disease—the most common form of dementia in older adults—your risk increases by about 30%. This is a relative risk increase, meaning a 30% hike in your existing risk.”
And if you’re age 65, the risk of being diagnosed is 2% a year; at the same time, the experts point out, this means you have a 98% chance of not developing Alzheimer’s. Concretely, the 2% figure means that two out of 100 65-year-olds will develop dementia every year.
Family history, the Harvard article says, increases the 2% annual risk by about 30%, to 2.6% per year. That means going from 20 cases in a group of 1,000 to 26 in 1,000, or six additional cases in 1,000. “So the absolute increase is relatively small,” Marshall says.
In fact, age is a bigger factor than family history when it come to Alzheimer’s. People in their 70s have a 5% chance of getting Alzheimer’s. That’s more than twice the risk of people in their 60s. Family history, the article says, “raises this by 30%, from 5% to 6.5%. Again, the absolute change is relatively small.”
Should you be tested for Alzheimer’s if a close relative has it? Basically, the answer is no. “It’s not going to be helpful,” Marshall says, “since it won’t tell you whether you will develop the disease. It will only tell you if you are at a greater or lower risk.”
And that may leave you living in fear, or making life decisions based on a negative view of your future.
The article goes on to say: “For Alzheimer’s disease that begins later in life—the vast majority of cases—a gene called apolipoprotein E (APOE4) is associated with greater risk for dementia. If you inherit one copy of APOE4, your risk triples. If you have two copies, your risk is 10 to 15 times higher, although that is rare.”