You can't change your genes, but you can change your behavior, right? Well, a new study finds that people who have a genetic test result that tells them they are at higher risk for lung cancer or heart disease aren't likely to change their health behaviors anyway.  

Researchers in England found that providing people with information about their estimated genetic risk for developing certain diseases, such as diabetes, lung cancer, skin cancer or heart disease, had little or no effect on their health-related behavior, according to the study, published today (March 15) in the journal The BMJ.

The results from genetic tests were just not a factor that motivated people to change their lifestyle habits, especially when it came to quitting smoking and getting more exercise, the study showed.

For example, smokers who found out they had an increased genetic risk of developing lung cancer were not more motivated to stop smoking than those who were not told they had a higher genetic risk of lung cancer. And telling middle-aged men and women they were more likely to develop diabetes did not appear to encourage them to begin a regular exercise program, according to the study. 

These findings were not surprising, said Theresa Marteau, lead author of the study and a professor of behavior and health at the University of Cambridge in England. Other studies have shown that communicating information about perceived risk generally has a small impact on the types of health behaviors that were evaluated in this review study, namely, smoking, physical inactivity and diet, she said. [9 Healthy Habits You Can Do in 1 Minute (Or Less)]

In the review study, the researchers analyzed data collected from 18 different studies of more than 6,100 adults ages 30 to 56. The studies all involved one group of participants who received personalized, DNA-based estimates of their disease risk for conditions whose risk could be reduced by behavior change, compared with a second group who did not learn their disease risk from genetic testing.

Personalized genetic testing

Companies that offer "personalized medicine" or sell genetic-testing services to consumers may claim that obtaining these results could possibly motivate people to change their behaviors and benefit their health.  

But the new findings suggest this is not the case.

The reason may be that people aren't motivated to make changes that may reduce their risk of longer-term threats, such as the possibility of developing diabetes in the next 10 years, Marteau told Live Science.

She said another reason why the risk estimates may not have much influence is because the behavior that needs to change is one that is routine or habitual, such as eating cookies with coffee, and it's easy to continue doing that because people live in an environment with a ready supply of cheap, tasty cookies and coffee.

"Information is, at best, a weak intervention for changing behavior," Marteau said.

The results from this review provide no evidence to support the use of personalized genetic testing as part of policies to change people's behavior to prevent common, complex diseases, such as diabetes, heart disease and many forms of cancer, she said.

Instead of relying on information to help change people's behavior on a large enough scale to prevent chronic diseases, a more effective approach is to change cues in the environment to make healthier behavior more likely, Marteau said.

For example, this may involve putting cigarettes in plain packets to remove branding cues that may appeal to children, serving beer in straight rather than curved glasses to reduce the speed and overall consumption of alcohol, and placing food on smaller plates to reduce the amount eaten at meals, she said.

However, although information from genetic testing may have little effect on changing health behavior, it may have other benefits, she noted.

The tests may have a role in dividing populations by their risk level, so that people at increased risk of a given condition could be offered treatment, such as surgery or medication, or be given more frequent screenings for that condition to help reduce their risk, Marteau said. [7 Diseases You Can Learn About from a Genetic Test]

Or the test results could be supplemented by the offer of effective behavior-change programs, such as smoking cessation programs that use a combination of behavioral and pharmacological strategies, and commercial weight-loss programs, such as Weight Watchers, she said.

People will see genetic-testing kits and may want to buy them to learn their risks of disease, and some may purchase the test, thinking it will motivate them to change their behavior, Marteau said.

But, she advises, "buyer beware." Consumers should understand that the scientific evidence suggests that they would be as likely or as unlikely to change their health behavior had they not undergone genetic testing, Marteau said.

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