Happy or sad? Single gene controls mood

26 Feb 2009, 0008 hrs IST, AFP

PARIS: Whether you see life as a glass half-empty or half-full may depend on a single, hormone-delivery gene, scientists in Britain reported on Wednesday. Some folks, in other words, are likely hard-wired for happiness while others are genetically gluttons for gloom, they suggested in a study published in Britain’s Proceedings of the Royal Society B.

Earlier research had already established that the gene known as 5-HTTLPR plays a key role in determining how the neurotransmitter serotonin functions within the brain. Serotonin, a hormone, transmits chemical messages between nerve cells, and has been closely linked to mood. Several anti-depressant drugs regulate serotonin levels.

Experts had identified three variants of the gene. Two “short” alleles, or variants, were linked to a higher risk of depression and suicidal tendencies. Unlike the third “long” allele, they were also thought to trigger an exaggerated neurochemical response to stressful situations.
A trio of researchers from the University of Essex in Britain led by Elaine Fox decided to find out if people with different variants were more or less drawn to or repelled by both distressing and pleasing situations.

Images categorized as negative designed to inspire fear or stress, erotic or pleasant ones, and neutral ones were shown to 97 participants. The 16 participants who had the long variant of the 5-HTTLPR gene “showed a marked avoidance of negative material alongside a vigilance for positive material,” the researchers found.

They paid close attention to the pretty pictures, in other words, and screened out the frightening ones. By contrast, the short allele groups showed opposite preferences, though not as strongly.