OBJECTIVETo understand the environmental risk factors on attempted suicide, and to study the interaction between factors as gene polymorphism of catechol-O-methyltransferase (COMT) associated to attempted suicide.

METHODSPaired case-control study of 205 suicide attempters (89 male, 116 female) and molecular biological techniques were used to study the relation between gene polymorphism of COMT, environmental factors and the rate of attempted suicide. Controls were paired with cases according to the same gender, similar age (no more than 3 years) and in the same district.

RESULTSThere were no significant differences in gene types and gene frequency between case and control groups. Multivariate conditional logistic regression model analysis showed that COMT Val/Val 158/108, low education level, cigarette smoking, emotional conflicts, psychologic disorders and depression were risk factors of attempted suicide with OR values as 2.43 (95% CI: 1.10 - 5.40), 5.70 (95% CI: 1.88 - 17.27), 3.54 (95% CI: 1.02 - 12.36), 10.96 (95% CI: 4.74 - 25.34), 6.35 (95% CI: 1.68 - 24.05) and 11.30 (95% CI: 4.58 - 27.89) respectively. There was no first level interaction between any two risk factors.

CONCLUSIONThe study supported that low education level, cigarette smoking, affective conflicts, psychiatric disorders, depression were risk factors of attempted suicide and COMT Val/Val 158/108 was suspected to be a susceptible gene type of attempted suicide but needs further study. The study also suggested that 116 bp in gene atlas be possibly correlated to high activity of COMT.