Researchers optimistic about the prospects of personalized medicine have long asserted that knowledge of genetic predisposition to certain diseases would improve public health by allowing for earlier interventions. However, changing human behavior is not so simple, according to the work of one researcher in the UK.
Theresa Marteau, a professor of psychology at King’s College in London spoke at a conference sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases earlier this month about how genetic susceptibility information impacts behavior.
In her research, she found that the interplay between an individual’s knowledge of a genetic risk and a decision to alter his behavior as a result of that knowledge is not so straightforward.
Marteau is currently investigating for the UK’s Medical Research Council how genotype analysis of people at risk of developing Crohn’s disease impacts their decision to stop smoking. The risk of developing Crohn’s disease can be predicted by testing for mutations in the NOD2 (CARD15) gene, by considering family history, and by factoring in smoking status.
The study, which began in April 2007, has so far enrolled 10 percent of the 540 first-degree relatives of Crohn’s disease patients. The primary outcome of the study is to see whether study participants will stop smoking for 24 hours or longer in the six months after learning their risk information. The secondary outcome is to gauge the proportion of participants stop smoking for seven days or longer at the six-month follow up. Smoking status will be biochemically verified.
So far, investigators have encountered patients who – after learning that they have a genetic predisposition for Crohn’s disease and that smoking increases their risk of getting the disease from 2 percent to 4 percent – still continue to smoke, reasoning that there are “greater risks” to their health than Crohn’s disease.
Other patients, meanwhile, stopped smoking – not after they learned of their genetic predisposition – but at the onset of the study, when they found out that researchers were studying the link between smoking and Crohn’s disease.
In conducting literature reviews of clinical studies, Marteau has found that while some patients who learn they are genetically predisposed to certain illnesses will try to alter their lifestyle to help mitigate those risks, on the whole, genetic risk information plays a small role in causing people to change their behavior.
Furthermore, Marteau’s research suggests that knowledge of genetic risk factors does not affect an individual’s behavior if the most effective way to mitigate that risk is through medication. However, people do change their behavior if the overall disease risk can be lessened by a lifestyle change.
This “speaks to the adaptiveness of humans.”
Additionally, some experts fear that individuals who find out their genetic risk for certain diseases may succumb to fatalism, the belief that events surrounding their health are predetermined and inevitable.
For instance, EuroGentest, an EU-funded project that aims to educate people about genetic testing, has issued leaflets in certain member countries that discuss the risks and psychological concerns associated with genetic testing [see PGx Reporter 05-09-2007].
“Taking a genetic test, waiting for the results, and then receiving them may cause a range of mixed emotions such as relief, fear, anxiety, or guilt,” according to the brochure. “It is important to think through the possible consequences for you and your family if you were to receive either good news or bad news; even though a genetic test may confirm a diagnosis, there may be no intervention or treatment available.”
But Marteau’s research suggests that knowing one’s genetic predisposition for a disease doesn’t necessarily trigger thoughts of impending illness or death.
This “speaks to the adaptiveness of humans,” said Marteau.
Marteau’s research on smoking cessation and Crohn’s disease is ongoing. The clinical trial is slated to finish in January 2009. It was not immediately clear what kinds of patient populations, including breakdowns by race and gender, are being surveyed.
Behavioral research of this kind certainly has implications for companies like Navigenics, 23andMe, and DeCode, who are aggressively marketing genotyping services to the general public. Marteau’s findings about how people react to and use DNA risk information may put into question the utility of these consumer genomics offerings.
In Marteau’s opinion, gene susceptibility studies should include a behavioral component so that researchers may learn how people will use this information and how the data can be better presented to help patients.
At the same conference, Colleen McBride, head of the Public Health Genomics Section of the National Human Genome Research Institute, discussed an ongoing project called the Multiplex Initiative, which is doing just that: testing people’s genetic susceptibility to eight common diseases and then gauging how the participants use the information.
Three years ago, McBride and Larry Brody, a senior investigator in NHGRI's Genome Technology Branch, started the Multiplex Initiative, which aims to examine the effects of genetic susceptibility testing for type 2 diabetes, coronary heart disease, hypercholesterolemia, hypertension, osteoporosis, lung cancer, colorectal cancer, and malignant melanoma.
NHGRI's Bioinformatics and Scientific Programming Core has created an online program under the Multiplex Initiative to help collect behavioral data after patients get genetically tested and receive their results. Each study participant will be presented with the pros and cons of genetic testing through the web-based program. The researchers will take note of what information the participants seek and how long they spend at each portion of the site.
McBride said that she hopes that this data will help NHGRI discern the most effective way of offering genetic testing and information. With this project “we can provide unobtrusive information and see how [participants] use that,” McBride said at the conference.
NHGRI’s Genome Technology Branch began recruiting patients for the Multiplex Initiative in February 2007. McBride said she hopes to finish enrolling patients in the next few months.
The Multiplex Initiative has a goal of recruiting 1,000 participants from a large primary healthcare system in the Midwest. As of March 10, the researchers had interviewed 1,648 people, of which 486 had gone to the project website, 408 agreed to be genetically tested, 250 had their blood drawn, and 83 have received their results.