Highly variable suicidal ideation: a phenotypic marker for stress induced suicide risk.

Suicidal behavior (SB) can be impulsive or methodical; violent or not; follow a stressor or no obvious precipitant. This study tested whether childhood trauma, affective lability, and aggressive and impulsive traits predicted greater SI variability. We also assessed whether affective lability, aggressive or impulsive traits explain childhood trauma's effects on SI variability and whether those with highly variable SI respond to stressful events with increases in SI. Finally, we assessed variable SI's trajectory over 2 years. Depressed participants (n = 51) had ecological momentary assessments (EMA) over 7 days at baseline, 3, 6, 12, 18, and 24 months. SI variability was assessed using the square Root of the Mean Square of Successive Deviations. Mixed Effects Models were fit as appropriate. Childhood trauma was associated with subsequent aggression. Physical abuse predicted both aggression and affective lability as well as SI variability, but not impulsivity. In two-predictor models, physical abuse's effect on SI variability was no longer significant, when controlling for the effect of higher aggression and impulsivity. Those with high SI variability exhibited greater increases in SI after stressors compared with those with less variability. We did not find that SI variability changed over time, suggesting it might be trait-like, at least over 2 years. Variable SI predisposes to marked SI increases after stressful events and may be a trait increasing risk for impulsive SB, at least over 2 years.