The relevance of the interpersonal theory of suicide for predicting past-year and lifetime suicidality in autistic adults

Abstract

Background: While there are known risk factors for suicidality in autistic adults, these are often unconnected from theoretical frameworks that might explain why risk is elevated and guide clinical interventions. The present study investigated the relevance of constructs from the Interpersonal Theory of Suicide (ITS), including perceived burdensomeness, thwarted belongingness and acquired capability for suicide, and explored mechanisms through which certain risk factors (relationship status, age at diagnosis) might elevate suicide risk.

Methods: Autistic adults (n = 314) completed an online study including measures of depression, anxiety and constructs from the ITS. Linear and multinomial regression analysis disentangled contributions of ITS variables from effects of depression and anxiety for past-year suicide ideation, past-year and lifetime suicide attempts. Mediation analyses examined associations between risk factors and these suicide outcomes via mechanisms proposed by the ITS.

Results: Past-year suicide ideation was associated with burdensomeness, mental rehearsal of suicide plans (a facet of acquired capability), and depression. Greater feelings of burdensomeness, and reduced fear of death, marked out participants who had attempted suicide in comparison to those who had experienced suicide ideation in the past year. Relationship status was indirectly associated with past-year suicide ideation via the mediators of depression and burdensomeness, and was associated with past-year attempts via its effect on ideation. Age at diagnosis was unrelated to any variables.

Limitations: Cross-sectional research is insensitive to causality and temporal dynamics, which is likely why interaction hypotheses from the ITS were unsupported. Normative measures may be invalid in autistic samples. There was no control group. The autistic sample was unrepresentative of the whole population, particularly autistic people with intellectual disabilities, ethnic/racial minorities, and gender minorities.

Conclusions: Perceived burdensomeness and acquired capability appear potentially important to suicide in autistic people, and may mediate the effects of some risk factors. Future research should explore the temporal dynamics of suicide trajectories in longitudinal, prospective designs.

Keywords: Acquired capability; Age at diagnosis; Perceived burdensomeness; Relationships; Suicide; Thwarted belongingness.

Fig. 1

Note. Frequency of responses to the two items assessing past-year suicide ideation (top row). On the bottom row are displayed the frequency of scores in the suicide ideation composite and the number of lifetime suicide attempts endorsed by participants

Fig. 2

Note. Indirect effects of relationship status on past-year suicide ideation and attempts. The coefficients of associations significant below the corrected alpha level (.025) are marked by bold lines and a single asterisk (*); those significant at p < .001 are depicted by bold lines and three asterisks (***). Dotted lines reflect associations that were not significant