Impulsiveness, serotonin genes and repetition of deliberate self-harm (DSH)

Background. Few studies have investigated independent associations of psychological, biological and social variables with repeated deliberate self-harm (DSH). Serotonin function has been linked to impulsive and suicidal behaviour and genetic polymorphisms have been identified within the serotonin system that could account for this link. This study tested hypotheses linking impulsiveness, genetic polymorphisms of tryptophan hydroxylase (TPH) and the 5-HT2c receptor and repeated DSH. Methods. Individuals presenting after DSH were interviewed, completed personality questionnaires and gave venous blood samples. Genotypes were determined for TPH intron7 and 5-HT2c (cys-ser) polymorphisms. Follow-up to identify repetition of DSH was for 1 year. Results. Males with the 5-HT2c serine variant were more impulsive than those with the cysteine variant (0.39 standardized units, P = 0.041, 95 % CI 0.017 to 0.076). There was no association between impulsiveness and the TPH intron7 polymorphism overall but a weak association with the L allele in men (0.41 standardized units, P = 0.05, 95 % CI 0.001 to 0.82). Impulsiveness, although high in the group as a whole, did not distinguish those who repeated DSH. Conclusions. The personality trait of impulsiveness may in part be related to genotypes of the 5-HT2c receptor and TPH gene in men. Impulsiveness does not differ between those who do and do not repeat DSH.