Separate and interactive contributions of weak inhibitory control and threat sensitivity to prediction of suicide risk

摘要

Biobehavioral dispositions can serve as valuable referents for biologically-oriented research on core processes with relevance to many psychiatric conditions. The present study examined two such dispositional variables—weak response inhibition (or disinhibition; INH−) and threat sensitivity (or fearfulness; THT+)—as predictors of the serious transdiagnostic problem of suicide risk in two samples: male and female outpatients from a U.S. clinic (N=1,078), and a population-based male military cohort from Finland (N=3,855). INH− and THT+ were operationalized through scores on scale measures of disinhibition and fear/fearlessness, known to be related to DSM-defined clinical conditions and brain biomarkers. Suicide risk was assessed by clinician ratings (clinic sample) and questionnaires (both samples). Across samples and alternative suicide indices, INH− and THT+ each contributed uniquely to prediction of suicide risk—beyond internalizing and externalizing problems in the case of the clinic sample where diagnostic data were available. Further, in both samples, INH− and THT+ interactively predicted suicide risk, with individuals scoring concurrently high on both dispositions exhibiting markedly augmented risk. Findings demonstrate that dispositional constructs of INH− and THT+ are predictive of suicide risk, and hold potential as referents for biological research on suicidal behavior.