Most healthy young adults place greater emphasis on health habits than on genetic risk factors when considering what causes common diseases, a research team from the National Human Genome Research Institute (NHGRI) and the Henry Ford Health System in Detroit has found. The study, based on a survey of 25 to 45-year-olds, was released June 8, 2010 in an early online edition of the Annals of Behavioural Medicine.

The research is part of the Multiplex Initiative, a large, population-based study of how healthy young people use genetic risk-susceptibility tests. Multiplex genetic testing, for which a single blood sample per individual is used to detect multiple genetic results, provides individuals with a slightly higher or lower comparative risk value for certain conditions compared to the general population.

"Genetic information is quickly becoming an important part of the equation for making individual health choices," said NHGRI director Eric Green. "It is important that we understand how genetic test recipients react and use such information so that the public, clinicians and public health experts have realistic expectations of how genetic risk awareness may affect the health information landscape."

Participants in the study were offered multiplex genetic testing designed to yield information about 15 different genes that play roles in eight preventable conditions, including type 2 diabetes, coronary heart disease, high blood cholesterol, high blood pressure, osteoporosis, lung cancer, colorectal cancer and malignant melanoma.

In the not-too-distant future, with wider availability of genetic testing, genetic risk information will more often be an added element in the health risk equation.

"Genetic tests for common conditions are being hailed as new tools that may enhance a person's general health awareness," said study co-author and lead Multiplex Initiative researcher Colleen McBride, senior investigator and chief of NHGRI's Social and Behavioural Research Branch. "We know very little about whether individuals understand how such genetic risk results interplay with other, well-known risk messages aimed at this population. It is critically important to learn more about the ways that people who receive personalized genetic risk results seek out health information and use it, and whether it influences their health behaviours."

In the study, the researchers surveyed 1,959 members of the Henry Ford Health System who responded to questions about behavioural risk factors, family history, beliefs about what might be the causes of the eight diseases, and health information preferences. The researchers also recorded the respondents' behavioural risk factors, such as physical activity, diet, smoking, alcohol consumption, sun exposure, multivitamin use and body mass.

A key focus was how respondents perceived how health behaviours and genetic makeup could cause a disease. The researchers also probed whether people learning about a disease placed more importance on learning about behaviours or genetics.

Two-thirds put greater emphasis on learning about the effects of lifestyle habits, and half placed equal importance on learning about the effects of genes.

People with more habits that put their health at risk tended to favour genetics to explain health conditions. They also tended to place less value on learning about how health habits affect disease risk.

One possible explanation suggested by the authors is that people with unhealthy lifestyle practices might see less value in lifestyle information because they may have tried to change their lifestyles in the past and failed. "As a result, these individuals may see less value in this information," said Dr McBride.

Behavioural theories suggest that people combine beliefs about the causes of health conditions with their own personal risk factors, such as high-calorie diet, consumption of alcohol and use of tobacco products, to evaluate genetic and behavioural health information. Health risk information prompts people to formulate beliefs and sometimes worries about what causes disease, as well as strategies to reduce the perceived threat of the disease. People can muster defensive responses such as denial, as well, if the information is too threatening.

The study also indicated that family history may be an effective motivator of health behaviour change. Those with a family history of disease placed greater value on pursuing genetic information and information about changing health habits than those without such a history.

"The study was designed to give a broad sense of how the public thinks about genetics and engages with information about common disease risk," said lead author Suzanne O'Neill, assistant professor of oncology at the Lombardi Cancer Center of Georgetown University, Washington. "The results from this study have provided - greatly needed information to guide future behavioural research on how to effectively translate genome science to benefit the public's health."