Measuring impulsivity differently yields different answers: A three-level meta-analysis of associations between impulsivity and adolescent non-suicidal self-injury.
Abstract
Background
Impulsivity is frequently examined in relation to adolescent non-suicidal self-injury (NSSI), yet the strength of this association remains unclear because findings vary across studies. This study quantified the association and examined potential sources of heterogeneity.
Methods
A three-level random-effects meta-analysis of 37 studies (N = 69,572) accounted for hierarchical dependencies among effect sizes. Potential moderators included assessment modality (self-report scale, semi-structured interview, or neurocognitive task), specific measurement instrument, impulsivity domain, sample source, and psychiatric comorbidity.
Results
Impulsivity was significantly associated with NSSI severity (d = 0.46) and was higher among adolescents with NSSI than controls (d = 0.37). Effect sizes varied significantly across specific impulsivity measurement instruments after FDR correction. In contrast, the omnibus test of broader assessment modalities was nonsignificant. Separately, self-report scales yielded a significant pooled estimate (d = 0.48), whereas neurocognitive tasks yielded a small and nonsignificant estimate (d = 0.11); these subgroup estimates do not establish modality differences. Neither sample source nor psychiatric comorbidity significantly moderated the association. Trait and symptom-level impulsivity yielded significant pooled estimates (d = 0.48 and 0.40, respectively). Negative urgency showed a relatively large pooled estimate (d = 0.60) based on only four effect sizes.
Limitations
Several moderator estimates were based on few effect sizes, limiting their precision.
Conclusions
Impulsivity is an important but nonspecific correlate of adolescent NSSI. Heterogeneity was more consistently associated with specific measurement instruments, highlighting measurement specificity when interpreting the impulsivity-NSSI literature. Self-report and neurocognitive measures may capture partly different aspects of impulsivity, warranting further multimethod research.