People who smoke, take drugs or drink heavily could have their genes to blame for their unhealthy lifestyles, Cancer Research UK scientists reveal in a study1.
Researchers found that certain differences in genetic make-up may be related to an individual’s attitude to health or their susceptibility to addiction.
The large-scale study, involving over 20,000 people, provides the strongest evidence yet that particular human genes can influence behaviour. It is being hailed as an important advance in understanding why some of us continue to ignore health warnings over tobacco and alcohol or find it particularly difficult to give up our bad habits.
Scientists from the Cancer Research UK General Practice Research Group at the University of Oxford combined and re-analysed data from 46 separate studies on the link between inheritance and behaviour.
Their research focused on key genes that control chemical signalling in the brain. Different versions of these genes may affect the balance of signalling molecules and in turn help to shape individual personalities.
Researchers found that one particular genetic variant – a version of the human serotonin transporter gene (5HTT-LPR) – was strongly associated with anxious personalities, of the kind that find social interaction stressful and may take refuge in substance abuse.
They also found a weaker link between a variant in a second gene – the dopamine D4 receptor – and extrovert personality traits. This may make an individual more likely to try cigarettes or other substances in the first place, because of a tendency to take risks with their health and to seek out novelty.
Lead researcher Dr Marcus MunafÃ², of the Cancer Research UK GP Research Group, says: “Our study suggests that there’s a genetic basis to certain kinds of personality trait, which may be important in influencing whether people take up habits like smoking or whether they can subsequently give them up.”
“Understanding genetic influences on personality is important if we are to design health campaigns that are effective for the widest possible range of people.
“We also know, through drugs such as anti-depressants, that is possible to influence these behaviours, and our research may open the way to new types of medication to help people overcome cancer-causing addictions.”
Scientists do not know precisely why particular genetic variants may influence personality, but they do have a few clues.
The 5HTT-LPR variant appears to reduce levels of the serotonin transporter molecule, in turn influencing levels of serotonin activity. This is an important chemical signalling molecule and controls emotions such as anxiety and depression.
Variations in the dopamine D4 receptor seem to alter the brain’s response to a second chemical signalling molecule – dopamine – which is thought to be associated with novelty seeking behaviour and pleasure, and may have a role to play in substance abuse.
Cancer Research UK’s Director of Clinical Research, Professor Robert Souhami, says: “Around half of all cancers are potentially preventable if people were to alter their lifestyles, so finding ways of changing behaviour is one of our key priorities.
“This research suggests that some people are particularly prone to the kind of unhealthy lifestyles that we know can be a cause of cancer. These people may be resistant to conventional health messages and may need subtler health warnings, or perhaps specific anti-addiction treatment for their particular personality type.”
- Molecular Psychiatry8 (5)