Communication difficulties in adults with Intellectual Disability: Results from a national cross-sectional study

•Over 57 % of a population sample of adults with ID reported communication difficulties.•Difficulties were described as severe in almost a quarter of the sample (23.5 %).•Level of ID, residential setting, and social participation were significant factors.•Challenging behaviours, and a diagnosis of Down syndrome were also important risk factors for communication difficulties. People with an intellectual disability (ID) are vulnerable to communication impairments, with consequences for employment, education, and social participation. To identify the communication skills of a population of adults (40+ years) with ID and explore relationships between individual and environmental factors and communication skills. Data from a sample of 601 adults with ID was selected from the Intellectual Disability Supplement to The Irish Longitudinal Study on Ageing (IDS-TILDA) addressing communication characteristics, demographics, co-morbidities, challenging behaviours, and social participation. A multiple regression model and a decision-making tree were built to identify factors related to communication abilities. Overall, 57.9 % of participants experienced communication difficulties, with 23.5 % reporting severe difficulties. Only 75.1 % of participants communicated verbally; more than half found communicating with professionals and non-familiar partners difficult. Level of ID, low social participation, challenging behaviours, and diagnosis of Down syndrome were significantly associated with communication difficulties. Communication difficulties are prevalent in adults with ID and are influenced by complex factors. Interventions to enhance interaction and quality of life of individuals with ID should consider communication opportunities, needs, and barriers.