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Background: Suicide is the most serious outcome of major depression, yet not all depressed patients will commit suicide. Genes, along with other factors, might account for this difference. Serotonergic alterations have been observed in suicide and depression and impulsive-aggressive behaviors. Therefore, we aimed to identify predictors of suicide, considering genetic variation at the serotonin transporter (5-HTT) gene., Methods: We investigated the 5-HTT gene-linked polymorphic region (5-HTTLPR) and intron 2 (STin2) variants of this gene and their relationship to behavioral and clinical risk factors for suicide in a sample of depressed suicides (n =106) and depressed control subjects (n =152), diagnosed by means of proxy-based interviews., Results: We found a significant association of suicide completion with having at least one copy of the STin2 10 allele [chi(2)(1) = 10.833, p = .002]. No differences were found for the 5-HTTLPR variable number of tandem repeats. After controlling for behavioral and clinical risk factors for suicide, the STin2 variant remained a significant predictor of suicide in major depression when jointly considered with a family history of suicide (odds ratio 5.560, 95% confidence interval 1.057-29.247)., Conclusions: The STin2 locus might account, at least in part, for the observed familial aggregation of suicidal behavior. These results should be further explored in families where clustering of suicidal behavior is observed.

Objective: Major depression is a major risk factor for suicide. However, not all individuals with major depression commit suicide. Impulsive and aggressive behaviors have been proposed as risk factors for suicide, but it remains unclear whether their effect on the risk of suicide is at least partly explained by axis I disorders commonly associated with suicide, such as major depression. With a case-control design, a comparison of the level of impulsive and aggressive behaviors and the prevalence of associated psychopathology was carried out with control for the presence of primary psychopathology., Method: One hundred and four male suicide completers who died during an episode of major depression and 74 living depressed male comparison subjects were investigated with proxy-based interviews by using structured diagnostic instruments and personality trait assessments., Results: The authors found that current (6-month prevalence) alcohol abuse/dependence, current drug abuse/dependence, and cluster B personality disorders increased the risk of suicide in individuals with major depression. Also, higher levels of impulsivity and aggression were associated with suicide. An analysis by age showed that these risk factors were more specific to younger suicide victims (ages 18-40). A multivariate analysis indicated that current alcohol abuse/dependence and cluster B personality disorder were two independent predictors of suicide., Conclusions: Impulsive-aggressive personality disorders and alcohol abuse/dependence were two independent predictors of suicide in major depression, and impulsive and aggressive behaviors seem to underlie these risk factors. A developmental hypothesis of suicidal behavior, with impulsive and aggressive behaviors as the starting point, is discussed.

Suicide is known to vary according to season, with peaks in the spring and troughs in the winter. The presence of psychopathology is a significant predictor of suicidality, and it is possible that the seasonal variation of suicide completion may be related to seasonality in the manifestation of psychiatric disorders common to suicide completers. In the current study, we evaluated 115 French-Canadian male suicide completers from the Greater Montreal Area for DSM-IV psychiatric disorders using proxy-based diagnostic interviews. Subjects were assessed for seasonal differences in the prevalence of DSM-IV psychiatric diagnoses just before their deaths. Diagnoses of major depressive disorder (MDD) without comorbid cluster B personality disorders, and schizophrenia were differently distributed between seasons. Most (63.4%) subjects with MDD committed suicide in the spring/summer (P =.038). However, closer examination revealed that depressed suicides with comorbid cluster B personality disorders did not show seasonality, while 83.3% of depressed suicides without comorbid cluster B personality disorders committed suicide in the spring/summer (P =.019). 87.5% of those suicides with schizophrenia committed suicide in the fall/winter (P =.026), and the only suicide with schizophrenia who died in the spring/summer was also the only one without positive symptomology. Our study is limited to male suicide completers, and results should not be generalized to women. We conclude that seasonal variation in suicide manifests itself differently in patients with different psychopathology. These findings indicate that assessment of suicide risk may need to include consideration of possible seasonal effects, depending on psychopathology.