Valutazione del rischio genetico di comportamento suicidario nel disturbo bipolare: analisi di 737 pedigrees

Suicide is a significant cause of mortality in patients with major affective disorders(MAD). Suicidal acts are typically more lethal in MAD. A large contribution to the suicide risk derives from the presence of family history of suicidal behavior. Other clinical factors, such as treatment with lithium can reduce the suicide risk in patients with MAD. In this work the results of the distribution of suicidal behavior in a large sample of families with bipolar-spectrum disorder, and its relation to family history of MAD and bipolar disorder (BD) are presented. Methods: The lifetime prevalence of completed and attempted suicides was analyzed in 737 families of probands with MAD with 4,919 first-degree relatives (affected and unaffected). Cox proportional hazard regression models and logistic regression models were used to investigate the role of several clinical covariates on the risk of MAD, BD and suicidal behavior. Results: The lifetime prevalence of suicidal behavior (attempted and completed suicides) in 737 probands was at 38.4 ± 3.0%. Among the clinical variables, lithium treatment was associated with a decreased risk of suicidal behavior in probands (p =0.007). Family history of suicidal behavior contributed significantly to the joint risk of MAD and suicidal behavior (p = 0.0006) in first-degree relatives. Conclusions: These findings suggest that the liability to suicidal behavior has significant contribution from partially overlapping genetic factors underlying MAD and suicidal behavior itself. Even in the presence of high genetic risk for suicidal behavior, lithium treatment seems to decrease significantly the suicide rates.