Knowing genetic risk doesn't really help us

Genetic tests that predict people's risk for disease are becoming more common, but a recent study suggests that having that information doesn't mean people act on it.

The University of Cambridge study found that communicating the results of DNA tests has little or no impact on behaviour change, such as stopping smoking or increasing physical activity.

These results are timely, given high levels of interest in personalised medicine and increasing use of direct-to-consumer testing for a range of common complex disorders, say the research team, led by Professor Theresa Marteau.

They reviewed the results of 18 studies on the effects of communicating genetic risk estimates of heart disease, cancers, and Alzheimer's disease, for which behaviour change could reduce that risk.

Behaviours included smoking, alcohol consumption, diet, and physical activity. Other outcomes analysed were motivation to change behaviour and levels of depression and anxiety.

The results show that there were also no effects on any other behaviours (alcohol use, medication use, sun protection behaviours, and attendance at screening or behavioural support programmes).

There were also no effects on motivation to change behaviour, and no adverse effects, such as depression and anxiety.

Further analyses provided no clear evidence that communication of a risk-conferring genotype affected behaviour more than communication of the absence of such a genotype.

"Existing evidence does not support expectations that such interventions could play a major role in motivating behaviour change to improve population health," they concluded.

The study is published by The BMJ.