Abstract
We investigated whether there is an emotional processing deficit in ADHD and whether this only applies to specific emotional categories. In this PRISMA-compliant systematic review based on a pre-registered protocol ( https://osf.io/egp7d ), we searched MEDLINE, PsycINFO, ERIC, Scopus and Web of Science databases until 3rd December 2023, to identify empirical studies comparing emotional processing in individuals meeting DSM (version III to 5-TR) or ICD (version 9 or 10) criteria for Attention Deficit/Hyperactivity Disorder (ADHD) and in a non-psychiatric control group. Study quality was assessed with the Appraisal tool for Cross-Sectional Studies (AXIS). Eighty studies were included and meta-analysed (encompassing 6191 participants and 465 observations). Bayesian meta-analyses were conducted to compare individuals with ADHD and non-psychiatric controls on overall emotional processing measures (meta-analysis 1) and across emotional categories (meta-analysis 2). The type of stimulus employed, outcome measurement reported, age, sex, and medication status were analysed as moderators. We found poorer performance in both overall emotion processing (g = - 0.65) and across emotional categories (anger g = - 0.37; disgust g = - 0.24; fear g = - 0.37; sadness g = - 0.34; surprise g = - 0.26; happiness/positive g = - 0.31; negative g = - 0.20; neutral g = - 0.25) for individuals with ADHD compared to non-psychiatric controls. Scales items and accuracy outcome being the most effective moderators in detecting such differences. No effects of age, sex, or medication status were found. Overall, these results show that impaired emotional processing is a relevant feature of ADHD and suggest that it should be systematically assessed in clinical practice.