“Mummy, why am I never happy?” – “Blame your father; he gave you his ‘miserable’ gene.”
While the fact that physical traits such a eye colour and skin tone arise are governed almost exclusively by our genes has long been known, a personality trait such as whether an individual sees life as a glass half-empty or half-full intuitively seems to derive from the individual's environment and upbringing rather than their genes. However, researchers at the University of Essex in the U.K have recently conducted a study indicating a “genetically-driven tendency to look on the bright side of life”. In studying the genetic basis for this personality trait, the researchers were particularly concerned with the promoter region of the serotonin transporter gene (5-HTTLPR). A common polymorphism exists in this region resulting in short (S) and long (L) alleles. Several studies have indicated that the S allele modifies the synaptic availability of serotonin (a neurotransmitter linked to mood and aggression) and that S allele carriers “are at a higher risk of depression and suicide attempts if they are exposed to major traumatic life events”.
In the investigation, 97 participants were shown a series of slides consisting of two images with differing emotional valences; positive images to elicit feelings of happiness, neutral images or negative images to elicit feelings of fear or stress. The experiment measured which types of diagrams each participant focused on or avoided and theses results were analysed based on which alleles the participants possessed. The researchers found strong evidence of a much stronger bias or “vigilance for positive material” and a stronger “avoidance of negative material” in participants homozygous for the L allele (LL) than their heterozygous (SL) and S-allele-homozygous (SS) counterparts. It is stated that these tendencies are commonly “associated with enhanced sociability and mental health and well-being”. The S allele carriers (SS and SL) exhibited the reverse bias pattern but not at a significant level. However, this bias for negative material is associated with “emotional vulnerability”, “neuroticism and anxiety”.
While this investigation does not imply that the S and L alleles alone code for pessimism and optimism, it does suggest that some people maybe have a genetic predisposition to depression while others may have genetically-conveyed “emotional resilience to general life stress”. It is then interesting to consider that future treatments for depression may involve gene therapy and that this type of therapy could possibly change and individual’s entire outlook on life.
Dennis Yeow (S42053743)
References:
Journal Article:
Elaine Fox, Anna Ridgewell, and Chris Ashwin (2009) Looking on the bright side: biased attention and the human serotonin transporter gene U.K.: Proceedings of the Royal Society B 2009 : rspb.2008.1788v1-rspb.2008.1788. Available from: Here
Related Article:
Scientists test ‘happy’ gene. (2009) Australia: ABC News. Available from: Here
Diagram from: Here
