Relationships Between Social Anhedonia, Capacity for Social Pleasure, Loneliness, and Depressive Symptoms in Adults with Autism Spectrum Disorder and Typically Developing Never-Depressed and Depressed Comparisons

Background:  The social motivation hypothesis posits that individuals with Autism Spectrum Disorder (ASD) experience reduced levels of social pleasure and hedonic capacity for interpersonal and social rewards. In typically developing (TD) adults, especially among those with depression, such deficits have also been associated with increased loneliness. Exploring the relationships between measures of social motivation and loneliness with depressive and autism symptoms allows for a deeper understanding of the social experience of adults with ASD, including those with the common comorbidity of depression.

Objectives:  The present study investigated the relationship between social pleasure, social anhedonia, and loneliness, as well as measures of depressive symptoms and ASD traits, in adults with ASD, TD currently depressed adults, and TD non-depressed controls.

Methods: A total of n=57 adults aged 18-35 with verbal IQ>80 were recruited from three cohorts: ASD (n=23); TD with current depressive disorders (DEP, n=19); and TD comparison participants with no depression or anxiety history (TDC, n=15). All participants completed diagnostic screening and testing (including the Autism Diagnostic Observation Schedule [ADOS-2] and the Structured Clinical Interview for DSM-5 Disorders [SCID-5]), as well as self-report measures of capacity to experience social pleasure (Anticipatory and Consummatory Interpersonal Pleasure Scale; ACIPS), social anhedonia (Revised Social Anhedonia Scale; RSAS), and loneliness (Loneliness in Context Questionnaire; LiCQ). Participants also provided self-reported measures of autism spectrum traits (Autism Spectrum Quotient; AQ) and depressive symptoms (Beck Depression Inventory-II; BDI).

Results:  The ASD and DEP groups were not statistically different from each other on social interest/anhedonia measures (ACIPS and RSAS), though they showed less social interest and increased anhedonia compared to the TDC group. As a group, ASD reported greater loneliness than TDC but less loneliness than DEP. Within ASD, increased social anhedonia and decreased social pleasure were significantly associated with greater levels of loneliness (LiCQ), depression (BDI-II), and ASD symptoms (AQ). In DEP, increased social anhedonia was significantly associated with increased loneliness and depressive symptoms, and marginally significantly associated with increased ASD symptoms.

The integrity of the associations between social interest/anhedonia and loneliness was further explored when controlling for AQ and BDI-II scores in a multiple linear regression framework that is statistically equivalent to the assessment of partial correlations, where either AQ or BDI-II was added as a covariate. The TDC and DEP groups were collapsed into one TD group with greater variability in social motivation measures and depressive symptoms. When controlling for AQ across groups, increased RSAS and decreased ACIPS remained significant predictors of loneliness, except for the nonsignificant association between ACIPS and loneliness in ASD. When controlling for BDI-II scores, RSAS and ACIPS no longer significantly predicted loneliness, except for a marginally significant association between ACIPS and loneliness in the TD group (Figure 1).

Conclusions: Results indicate that decreased social interest and increased anhedonia are both associated with loneliness in TD and ASD adults. However, preliminary findings suggest that depressive symptoms, not ASD traits, in ASD and TD account for self-reported loneliness over and above measures of social interest/anhedonia.