Potential mechanisms underlying suicidality in autistic people with attention deficit/hyperactivity disorder (ADHD): testing hypotheses from the interpersonal theory of suicide.

Abstract

Background Autistic people with co-occurring ADHD appear to be at heightened risk of suicide. To understand why, we explored two explanatory mechanisms from the interpersonal theory of suicide: first, that co-occurring ADHD might be associated with greater risk through greater thwarted belongingness and perceived burdensomeness; and secondly, that hyperactive/impulsive features might incur additional risk through their association with painful and provocative events, which are suggested to create ‘capability’ for suicide. Methods Autistic adults (n = 314) completed an online survey including measures of thwarted belongingness, perceived burdensomeness, painful and provocative events, acquired capability for suicide, and ADHD features. Creating an overall index of likely ADHD, we examined associations between likely ADHD, suicide ideation and lifetime suicide attempts via the parallel mediators of thwarted belongingness, perceived burdensomeness, anxiety and depression. In several models, we then examined hyperactive, impulsive and inattentive features as predictors of exposure to painful and provocative events and subsequent capability for suicide, and examined whether these two variables, sequentially or individually, mediated an association with lifetime suicide attempts. Results Likely ADHD was associated with past-year suicide ideation via greater depression and perceived burdensomeness, which also mediated its association with more suicide attempts. Hyperactive and impulsive features were associated with exposure to painful and provocative events and through this acquired suicide capability. Both features were associated with more numerous suicide attempts via these two mediators sequentially, and via exposure to painful and provocative events alone. Conclusions These data suggest that suicidality in autistic people with ADHD may be partially related to perceived burdensomeness and to acquired suicide capability following exposure to painful and provocative events. However, as we observed a pathway to suicidality associated with painful and provocative events alone, it is likely that there are also other explanatory mechanisms for the influence of traumatic events on suicide risk.