Mood symptoms and suicidality across the autism spectrum

Autism spectrum is a psychopathological dimension which encompasses a wide range of clinical presentations: from subthreshold forms and autistic traits (AT), that can be found in the general population, to full-blown autism spectrum disorder (ASD). Many studies reported high rates of comorbidity between both ASD and AT and mood disorders, as well as a high prevalence of suicidal ideation among patients with ASD/AT. The aim of this study was to investigate the presence of mood symptoms and suicidal ideation and behaviors in patients with full-blown ASD and in subjects with AT, as well in a healthy control (HC) group, with a specific focus on which of the autistic features may be predictive of suicidal ideation and behaviors.

We recruited 262 adult subjects: 34 with ASD without intellectual impairment or language disability (ASD group), 68 fulfilling only one symptom criterion for ASD according to DSM-5 but who do not meet criteria for a full-blown diagnosis of ASD (AT group), and 160 HC. All subjects were assessed with the Structured Clinical Interview for DSM-5 (SCID-5); in addition, they were asked to fill two questionnaires: The Mood Spectrum, Self-report (MOODS-SR) and the Adult Autism Subthreshold Spectrum (AdAS Spectrum).

ASD subjects reported significantly higher AdAS Spectrum and MOODS-SR total scores, as well as higher MOODS-SR depressive component total scores, when compared with AT and HC subjects. AT subjects scored significantly higher than the HC group. No significant differences were reported between ASD and AT subjects for the suicidality score according to MOODS-SR, despite both groups scored significantly higher than the HC group. The strongest predictor of suicidality score were MOODS-SR depressive component score and AdAS Spectrum Restricted interests and rumination domain score.

Our results highlight a correlation between autism and mood spectrum, as well as between suicidality and both ASD and AT. Subthreshold forms of ASD should be accurately investigated due to their relationship with suicidal thoughts and behaviors.