Variations in 5-HTTLPR: relation to familiar risk of affective disorder, life events, neuroticism and cortisol.

Background: Variations in the serotonin transporter gene (5-HTTLPR) and stressful life events are associated with affective disorders.

Aim: To investigate whether the distribution of the alleles of the 5-HTTLPR is associated with a genetic predisposition to affective disorder and whether these variations interact with life events in relation to depressive symptoms, neuroticism and salivary cortisol.

Method: In a high-risk population study, healthy monozygotic and dizygotic twins with (high-risk twins) and without (low-risk twins) a co-twin history of affective disorder were identified through nationwide registers.

Results: When comparing the 81 individuals homozygote for the long allele with the 125 individuals hetero- and homozygote for the short allele no associations between the allele distribution and a genetic predisposition were found. The presence of the short allele of the 5-HTTLPR and the experience of SLE was associated with a higher neuroticism score, but not with depressive symptoms nor awakening or evening salivary cortisol.

Conclusion: A combination of variants in 5-HTTLPR and environmental stress seems to increase neuroticism in healthy individuals.