Suicidality in Autism Spectrum Disorder Comorbid with ADHD Symptoms in a Non-Clinical School-Aged Population
Objectives: However, to our knowledge, no studies have yet examined the relationship between ASD and suicidality considering the comorbidity of ADHD symptoms.Therefore, this study examined how ASD and ADHD symptoms interact with suicidal ideation in non-clinical school-aged population.
Methods: A 1-year, prospective school survey including 8,669 children aged 6–14 years at baseline and their parents was conducted in 2016 (time 1) and 2017 (time 2). At time 1, we administered parent-reported ASD and ADHD traits scale (ASD: Autism Spectrum Screening Questionnaire, ADHD: ADHD-Rating Scale)- and self-reported depression scale (Depression Self-Rating Scale for Children: DSRS-C)-based questionnaires, which included items of suicidal ideation. At time 2, DSRS-C was re-administered. For group comparison, participants were divided into eight groups according to the combination of ASD and ADHD traits: (1) non-risk, (2) ASD at risk, (3) inattention (IA) at risk, (4) hyperactivity (HA) at risk, (5) ADHD at risk, (6) ASD + IA at risk, (7) ASD + HA at risk, and (8) ASD + ADHD at risk. Kruskal–Wallis tests were performed with groups as an independent variable and suicidal ideation scores at time 2 as a dependent variable. Subsequently, a series of pass models was computed to examine whether ASD and ADHD traits predict suicidal ideation. Cross-sectional associations at time 1 and longitudinal associations at time 2 were examined.
Results: Kruskal–Wallis tests revealed that ASD and ADHD traits were risk factors for suicidal ideation. Pair-wise comparison revealed that suicidal ideation was significantly higher in the ASD + IA group than in the other groups (ASD + IA > ASD at risk, IA at risk, HA at risk, ADHD at risk, p < .01). Results of the path analysis revealed that higher ASD and IA traits were associated with higher levels of suicidal ideation at time 1 (ASD: b = .076 BCa, CI [.048, .103], p < .001; IA: b = .120 BCa, CI [.085, .155], p < .001). There was a significant indirect effect of ASD and IA traits on suicidal ideation at time 1 through suicidal ideation at time 2 (ASD: b = .040 BCa, CI [.025, .054], p < .001; IA: b = .062 BCa, CI [.044, .081], p < .001). These results indicate that higher ASD and IA traits predict a higher risk for suicidal ideation at time 2 by mediating suicidal ideation at time 1. HA traits consistently showed no significant association with depression and suicidal ideation.