Would you want to know your Alzheimer's risk?

Hidden within our DNA are clues about what the future might hold for each of us. Perhaps your genetic map points toward heart disease, while mine suggests glaucoma could be down the road. These aren't set-in-stone predictions, but rather signs of a genetic leaning, indicating a heightened risk for certain conditions. Scientists are getting better and better at coaxing such details out of our genes, which presents us with both an opportunity and dilemma: knowing that your genes are nudging you toward a preventable or treatable condition, such as type 2 diabetes, might allow you to take steps to stay healthy. But what if you learn you have a higher risk of getting a condition for which there isn't yet a cure or a means to prevent it, such as Alzheimer's disease? Is that information still worth knowing, and how would it make you feel?

These are some of the questions explored in a new study about the psychological effects of genetic testing for Alzheimer's. Overall, researchers found that people who learned they had a higher risk of Alzheimer's actually adjusted to the news quite well. In fact, they were just as likely to say they'd choose to have the test again as those who learned they were at lower risk.

The study included 162 people who had a parent with Alzheimer's disease. All were tested for a gene called APoE4. People who have this gene and also a close relative with Alzheimer's have more than a 50 percent chance of getting the disease by age 85. In contrast, people who have a family history of Alzheimer's but don't have this gene have between a 30 percent and a 35 percent chance. The risk for the general population is around 10 percent to 15 percent.

Although everyone in the study was tested for the gene, only two-thirds were given their results. Over the following year, the researchers used questionnaires to score and compare people's anxiety, depression, and test-related distress.

People who tested positive for the gene had slightly more distress at first than those who didn't learn their results. However, these feelings didn't last. When people were surveyed again after six months and after a year, the researchers found no difference in anxiety, depression, or distress scores.

For those who learned they'd tested negative for the gene, the test understandably provided some relief, and they had slightly lower distress scores as a result.

Everyone in the study had genetic counseling to help them understand their Alzheimer's risk and the limitations of the testing. So, it's likely that they were particularly well prepared to deal with their results. People might not cope this well if they don't get the same amount of support. This is a concern, say researchers, as genetic testing has now expanded beyond medicine to the marketplace, with companies selling genetic testing services directly to consumers. Although these firms usually provide some counseling to help people understand their test results and put their genetic risks in context, the extent of this counseling varies. This could leave some people overly anxious about test results they don't fully understand.

What you need to know. No test can predict with 100 percent accuracy who will get Alzheimer's disease, but genetic testing can tell you if your risk is higher than average. Unfortunately, there's not much you can do with this information. Drugs can slightly reduce the symptoms of Alzheimer's, but there's no cure or way to prevent the disease.

Even so, you may be interested in learning your risk, especially if you have a close family member with Alzheimer's. This study suggests that people who test positive for the APoE4 gene don't have any lasting distress as a result, which is good news. But I'm still not sure I'd have the test. Many doctors recommend against having genetic tests unless there's a definite medical benefit in doing so, and I can see the sense in that.

But, medical opinion aside, what do you think? Would you want to know? 

—Sophie Ramsey, patient editor, BMJ Group