Self-Reported Suicidal Ideation, Depression and Loneliness in Adults with Autism Spectrum Disorder (ASD)

Background: Previous studies report an exceptionally high rate of suicidal ideation (30 - 66%), plans or attempts at suicide (15 - 35%), and depression (31 - 70%), in adults with ASD, when compared to the general population (Balfe & Tantam, 2010; Cassidy et al., 2014; Raja, Azzoni, & Frustaci, 2011; Takara & Kondo, 2014). Depression is a significant risk factor for suicide, with symptoms present in at least 90% of individuals who die by suicide (Barraclough, Bunch, Nelson, & Sainsbury, 1974). However, studies on depression in ASD, and suicidal ideation in particular, are sparse and often anecdotal (Cassidy et al., 2014). Furthermore, adults with ASD may experience high rates of isolation and loneliness, both of which are associated with increased rates of depression (Mazurek, 2013), which may add to suicide risk.

Objectives: Our aim was to report and examine the relationship between self-reported depressive symptoms, suicidal ideation and loneliness in adults with ASD.

Methods: Participants were 76 adults (88% male) with ASD aged 17 to 56 years (M = 25.15, SD = 7.74 years) who were participating in a longitudinal employment study. Participants completed the Patient Health Questionnaire-9 (PHQ-9; Kroenke, Spitzer, & Williams, 2001), which includes a question concerning suicidal ideation, and the University of California Los Angeles Loneliness Scale (Russell, 1996; Russell, Peplau, & Cutrona, 1980; Russell, Peplau, & Ferguson, 1978). We report frequency of depressive symptoms (excluding ideation), ideation, and loneliness, and utilized correlation and mediation analysis (Hayes, 2013) to examine the relationship between these variables.

Results: Overall, 19.7% of the sample reported that they had experienced recent (last 2 weeks) thoughts that they would be better off dead, or of hurting themselves on several days (15.8%), more than half the days (1.3%), and nearly every day (2.6%). In terms of depressive symptoms, 25% of the sample were in the moderate to moderate-severe range, and 1.3% were in the severe range. Loneliness was significantly correlated with depressive symptoms (excluding ideation), r_s = .44, p < .001, but bore only a weak relationship with suicidal ideation, r_s = .29, p = .012. There was a significant indirect effect of loneliness on suicidal ideation through depression, b = .01; BCa CI [.004, .02], standardized effect size = .21; BCa CI [.10, .34].

Conclusions: Both the rates of suicidal ideation (19.7%) and at least moderate rates of depression (26.3%) were lower than those reported previously in adults with ASD. This difference may be accounted for by differences in methodology and sampling compared to previous studies which have, for example, used clinical interviews to ascertain ideation and history of suicide attempts in clinical groups (e.g., Cassidy et al., 2014). Nonetheless, these rates remain substantially higher than that for the general population, which are 3.7% and 6.2% for suicidal ideation and depression respectively (Crosby, Han, Ortega, Parks, & Gfroerer, 2011; Tiller, 2012). Importantly, we characterised the relationship between depression, loneliness and suicidal ideation, showing that depression mediated the relationship between loneliness and suicidal ideation.