ATLANTA (AP) – People who learn through genetic testing that they have a higher than average risk for Alzheimer's disease are able to handle the bad news pretty well, results from the first major study of this suggest.

The findings aren't enough evidence for doctors to urge more people to get genetic testing, said lead author, Dr. Robert Green. But they challenge assumptions that people will be devastated by a positive test result and misread it as certain proof they're doomed to Alzheimer's.

"Our participants were able to understand the risk and manage it," said Green, a researcher at the Boston University School of Medicine.

For many who learned they were not at increased risk, testing wound up being a great relief. The study is being published yesterday in the New England Journal of Medicine. Alzheimer's is the most common cause of dementia among older adults, and affects as many as five million Americans, most of them over age 60. The exact cause is not known, but scientists believe heredity plays a role. People with a certain gene – known as APoE4 – are believed to be three to 15 times more likely to develop the illness than other people, depending on how many copies of the gene they have. It is not, however, a sure sign someone will get the disease. Experts recommend a test for APoE4 only to diagnose Alzheimer's in patients already having symptoms. But a number of companies have been marketing the test directly to consumers, even though there is no cure for the disease or way to prevent it from developing.

"It's available if somebody wants it," said Beth Peshkin, a genetic counselor at Georgetown University Medical Center. The study measured anxiety, depression and stress levels in 162 healthy adults who were children or siblings of people with Alzheimer's.