SMOKING AND DRUG ABUSE TRAITS LINKED TO GENES

People who drink, smoke and take drugs could be more at the mercy of their
genes than was previously realised, research showed yesterday.

A study involving more than 20,000 people has suggested that particular
genes can influence personality traits linked to unhealthy behaviour.

Cancer Research UK scientists at Oxford University pooled data from 46
separate studies looking at the link between human behaviour and
inheritance. The research focused on genes that control chemicals used to
transmit signals between brain cells. The findings were published in the
journal Molecular Psychiatry.

Researchers found that one version of the human serotonin transporter gene
(5HTT-LPR) was strongly associated with anxious personalities. Individuals
with this gene variant were the sort who find social interaction stressful
and may take refuge in substance abuse.

The scientists found a weaker link between a variant in a second gene, the
dopamine D4 receptor, and extrovert personality traits. Such people are
more likely to smoke or take drugs because of a tendency to gamble with
their health and seek out novelty.

The chief researcher, Dr Marcus Munafo, said: "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 antidepressants, 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 have some clues.

The 5HTT-LPR variant appears to reduce levels of the serotonin transporter
molecule, in turn influencing levels of serotonin activity. Serotonin helps
to control emotions such as anxiety and depression.

Variations in the dopamine D4 receptor seem to alter the brain's response
to dopamine, which is thought to be associated with novelty seeking
behaviour and pleasure, and may have a role in substance abuse.