A longitudinal study of nonsuicidal self-injury in offspring at high risk for mood disorder.

Objective: To determine the demographic and clinical predictors of nonsuicidal self-injury and to examine the longitudinal relationship between nonsuicidal self-injury and suicide attempt.
Method: This was a longitudinal cohort study of the familial transmission of suicidal behavior. The sample consisted of probands with DSM-IV mood disorder (n = 212), 54.2% of whom were suicide attempters, and their offspring aged at least 10 years (n = 352), followed for a mean of 3.8 years. Personal, parental, and familial characteristics were assessed annually to identify the most parsimonious subset of these variables associated with nonsuicidal self-injury, the primary outcome. Data were collected between August 1998 and August 2007.
Results: Of 352 offspring, 7.4% (n = 26) engaged in nonsuicidal self-injury during follow-up. In the final model examining predictors at baseline, the most severe time point, and the time point prior to nonsuicidal self-injury, only predictors from the most proximal time point were significant, namely younger age (odds ratio [OR] = 0.75, P = .002), diagnosis of current major depression (OR = 5.09, P < .001), and suicidal ideation (OR = 1.46, P = .02). In 2 of the 3 single time point models, baseline nonsuicidal self-injury was the most significant predictor of nonsuicidal self-injury during follow-up. Suicide attempt was predicted by both baseline nonsuicidal self-injury and suicide attempt, but when both were included in the model, nonsuicidal self-injury was a significant predictor (OR = 7.50, P = .009), but suicide attempter was not (OR = 3.78, P = .08); offspring aggression (OR = 1.11, P = .01) predicted suicide attempt but not nonsuicidal self-injury. Parental histories of nonsuicidal self-injury, suicide attempt, and abuse were not predictive of nonsuicidal self-injury.
Conclusions: Nonsuicidal self-injury may be an earlier manifestation of a shared diathesis with suicide attempt, consisting of depression and suicidal ideation, and that diathesis may lead to suicidal behavior in the face of greater offspring aggression and family pathology. The apparent bidirectional temporal relationship between nonsuicidal self-injury and suicide attempt may be explained by this shared diathesis.
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