Attempted suicide and oxytocin-related gene polymorphisms

Background: Oxytocin may moderate prosocial behaviors, but has also been implicated in negative mental health outcomes. A single-nucleotide polymorphism (SNP) of the oxytocin receptor gene (OXTR), rs53576, and a SNP of the CD38 gene, which regulates oxytocin secretion, rs3796863, have been associated with depression and suicidal ideation. Methods: We conducted an exploratory study investigating the relationship of these two SNPs to history of suicide attempt. Secondary analyses explored relationships of genotype with sex, diagnosis, history of abuse, depression, suicidal ideation, and attachment and personality traits. Subjects were depressed adults with DSM-IV major depressive disorder (MDD; n=161) or bipolar disorder (BD; n=75). Results: The A allele of rs53576 was associated with suicide attempt history. A differential effect of rs3796863 genotype on suicide attempt risk was found by diagnosis. In the BD sample, CC and AC genotypes were associated with higher odds of suicide attempt compared to AA, while in the MDD sample, AC subjects were more likely than CC subjects to have made an attempt. Limitations: Our assessment of social sensitivity was limited to measures of attachment style and abuse history and did not differentiate between types of abuse. Plasma oxytocin was not measured. Conclusions: These findings add to evidence for the involvement of oxytocin in suicide attempts and identify a potential biomarker for differentiating depressed attempters from non-attempters.