Abstract
Given the elevated rates of suicidal ideation, suicide attempts, and nonsuicidal self-injury (NSSI) in autistic adults, we examined whether autism-informed traits and transdiagnostic personality tendencies jointly relate to these outcomes. One hundred and two adults with clinician-diagnosed autism completed structured clinical interview assessments of lifetime histories of suicidal ideation, attempts, and NSSI. Predictors were six Comprehensive Autistic Trait Inventory (CATI) subscales and selected Personality Inventory for DSM-5 Short Form (PID-5-SF) domains and facets. We fit CATI-only, PID-5 domain, and facet models, then combined significant predictors and refit with age, sex, and IQ as covariates. Shared variance between PID-5-SF facet Anhedonia and CATI Social Interactions showed suppression in joint models, and latent variable modeling confirmed that their shared variance-indexing overlapping reward and social disengagement-was the most consistent correlate of risk across outcomes. PID-5-SF facet Emotional Lability was robustly related to NSSI and to ideation severity. CATI Self-Regulatory Behaviors predicted NSSI. PID-5-SF domain Disinhibition showed no associations. Higher IQ showed a modest protective effect for attempts. Findings highlight central roles of reward-related processes and affective volatility, with added contributions from interpersonal strain and self-regulation. Combining CATI with PID-5 yields complementary targets for assessment and intervention. Key strengths include a clinician-diagnosed autistic sample, a rare direct comparison of people with lifetime suicidal ideation vs. suicide attempts, and an integrated trait framework that moves the field beyond prevalence toward trait-informed risk. Findings support brief screening for anhedonia and emotional lability, autism-adapted behavioral activation, rapid arousal-reduction skills, and attention to social communication needs that may impede disclosure and help-seeking.