Complex emotion recognition in neurological and neurodevelopmental conditions.

Social cognition deficits are prevalent but under-recognised in neurological and neurodevelopmental disorders. Complex emotion recognition (CER) - encompassing mentalising, theory of mind, and perspective-taking - is crucial for social functioning but lacks a standardised clinical assessment. We evaluated CER performance across neurological and neurodevelopmental populations using COSIMO, a novel online assessment tool with muted video clips of dyadic interactions, in six clinical cohorts compared to controls (HC, N = 449): temporal lobe epilepsy (TLE, N = 36), multiple sclerosis (MS, N = 64), autism spectrum disorder (ASD, N = 90), attention deficit hyperactivity disorder (ADHD, N = 54), and healthy adults aged >65 years (H65+, N = 35). Reduced CER scores were observed across all clinical groups compared with HC (n = 455): ASD (Hedges' g = -1.05, 95% CI -1.29 to -0.81), TLE (g = -0.60, 95% CI -0.94 to -0.25), H65+ (g = -0.52, 95% CI -1.02 to -0.01), MS (g = -0.51, 95% CI -0.77 to -0.24), and ADHD (g = -0.50, 95% CI -0.91 to -0.10). Significantly reduced scores were most prevalent for ASD (37%), H65+ (28%), and TLE (19%). Complex emotion recognition deficits are pervasive across clinical conditions, with the highest prevalence in individuals with ASD, TLE, and H65+. Our findings demonstrate the clinical importance of routine CER screening in these populations. The COSIMO test provides a practical solution for identifying patients at risk of social cognitive impairment who may benefit from counselling and targeted interventions.