Pubdate: Wed, 18 Jun 2003
Source: Independent  (UK)
Copyright: 2003 Independent Newspapers (UK) Ltd.
Contact:  http://www.independent.co.uk/
Details: http://www.mapinc.org/media/209
Author: John von Radowitz

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.
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