Sociodemographic, developmental, functional and medical profiles of autistic and non-autistic adults with intellectual disability attending a specialized clinic in Türkiye

Background Autism spectrum disorder (ASD) frequently co-occurs with intellectual disability (ID), yet comparative data in adult populations remain limited. This study aimed to compare adults with ID with and without ASD across sociodemographic, developmental, functional, and medical domains in a specialised clinical setting.Methods In this cross-sectional study, 329 adults with ID (170 with ASD, 159 without ASD) attending a tertiary outpatient clinic were evaluated using clinical assessments, medical records, and caregiver reports. Group differences were analysed using appropriate statistical tests.Results Adults with ASD were younger, more often male, less frequently employed, and more likely to have received special education. They also had fewer siblings and lower birth order. Developmentally, individuals with ASD showed higher rates of developmental regression and lower rates of delayed walking, while no significant difference was observed in speech delay. They demonstrated greater ID severity, poorer speech levels, and higher support needs. In contrast, non-ASD adults more frequently exhibited delayed walking, congenital anomalies, dysmorphic features, physical disability, and immobility. Medical comorbidities, including epilepsy, hypothyroidism, cerebral palsy, and overall medical burden, were more prevalent in the non-ASD group.Conclusions Adults with ID with and without ASD exhibit distinct clinical profiles, highlighting the need for tailored assessment and service planning.