Posted for Roberta Kwok

Researchers have linked a genetic variation to a tendency to avoid gloom. As described in a study published today, people who carry longer versions of a serotonin-related gene are drawn to pleasing images, while paying less attention to negative ones.

The gene affects levels of the mood-altering neurotransmitter serotonin in the brain, and its promoter region, called 5-HTTLPR, comes in short or long forms. Researchers took DNA samples from 97 people to determine which combination of alleles they had. They then showed pairs of pictures, one positive or negative and the other neutral, and gauged the participants’ reactions.

The 16 people with two long forms of 5-HTTLPR preferred the happy images and avoided the depressing ones, the study found. Those with at least one short allele did not show the same pattern and seemed to favour the negative images, though that effect was not statistically significant.

“We have shown for the first time that a genetic variation is linked with the tendency to look on the bright side of life,” says lead researcher Elaine Fox of the University of Essex, UK (press release). The findings appear in Proceedings of the Royal Society B.

Scientists have previously found that people with short alleles of the gene are more likely to be depressed or attempt suicide (AFP). They may also have more intense neurochemical reactions to stress.