Social and nonsocial reward moderate the relation between autism symptoms and loneliness in adults with ASD, depression, and controls.

Individuals with autism spectrum disorder (ASD) report high levels of co-occurring mood disorders. Previous work suggests that people with ASD also experience aberrant responses to social reward compared to typically developing (TD) peers. In the TD population, aberrant reward processing has been linked to anhedonia (i.e., loss of pleasure), which is a hallmark feature of depression. This study examined the interplay between self-reported pleasure from social and nonsocial rewards, autism symptom severity, loneliness, and depressive symptoms across adults with autism spectrum disorder (ASD; N = 49), TD currently depressed adults (TD-dep; N = 30), and TD never depressed controls (TD-con; N = 28). The ASD cohort reported levels of social and nonsocial anhedonia that were greater than TD-con but not significantly different from TD-dep. Across cohorts, both social and nonsocial hedonic capacity moderated the relationship between autism symptoms and loneliness: individuals with low capacity for pleasure experienced elevated loneliness regardless of autism symptom severity, while those with intact capacity for pleasure (i.e., less anhedonia) experienced greater loneliness as a function of increased autism symptoms. Loneliness was the strongest predictor of depressive symptoms across clinical cohorts. Our findings suggest a putative pathway from trait-like anhedonia in ASD to depression via elevated loneliness and indicate that variability in hedonic capacity within the autism spectrum may differentially confer risk for depression in adults with ASD. Results underscore potential mental health benefits of social skills interventions and community inclusion programs for adults with ASD. Autism Res 2019, 12: 884-896. (c) 2019 International Society for Autism Research, Wiley Periodicals, Inc. Lay Summary The relationship between autism symptoms and loneliness depended on one's ability to experience both social and nonsocial pleasure. Adults who experienced less pleasure reported high levels of loneliness that did not depend autism severity, while adults with high capacity for pleasure were especially lonely if they also had many autism symptoms. Loneliness was the strongest predictor of depressive symptoms, compared to capacity for social and nonsocial pleasure and autism symptoms.