Clements CC, et al. - The researchers carried out a systematic review and meta-analysis to investigate if people with autism spectrum disorder (ASD) process rewarding stimuli differently than typically developing individuals (controls), whether differences were limited to social rewards, and whether contradictory findings in the literature could be due to sample characteristics. Researchers reported that people with ASD exhibited atypical processing of social and nonsocial rewards. The study results support a broader interpretation of the social motivation hypothesis of ASD whereby general atypical reward processing encompasses social reward, nonsocial reward, and perhaps restricted interests, and also suggested that prior mixed results could be driven by sample age differences.

Methods

• From database inception until June 1, 2017, articles were identified in PubMed, Embase, and PsycINFO.
• Most authors provided functional MRI data from these articles.
• Researchers involved publications that provided brain activation contrasts between a sample with ASD and controls on a reward task, determined by multiple reviewer consensus.
• Multiple reviewers extracted peak coordinates and effect sizes from articles to recreate statistical maps using seed-based d mapping software when functional magnetic resonance imaging (fMRI) data were not provided by authors.
• They performed random-effects meta-analyses of responses to social, nonsocial, and restricted interest stimuli, as well as all these domains together.
• Secondary analyses involved meta-analyses of wanting and liking, meta-regression with age, and correlations with ASD severity.
• In accordance with Meta-analysis of Observational Studies in Epidemiology guidelines, all procedures were conducted.
• Brain activation differences between groups with ASD vs typically developing controls while processing rewards was the main outcome.
• Before data collection, all analyses except the domain-general meta-analysis were planned.

Results

• Thirteen studies (30 total fMRI contrasts) from 259 people with ASD and 246 controls were included in this meta-analysis.
• It was noted that autism spectrum disorder was related to aberrant processing of both social and nonsocial rewards in striatal regions and increased activation in response to restricted interests (social reward, caudate cluster: d = -0.25 [95% CI, -0.41 to -0.08]; nonsocial reward, caudate and anterior cingulate cluster: d = -0.22 [95% CI, -0.42 to -0.02]; restricted interests, caudate and nucleus accumbens cluster: d = 0.42 [95% CI, 0.07 to 0.78]).