["Journal of Intellectual Disability Research, EarlyView. ", "\nABSTRACT\n\nObjectives\nThe objective of this study is to investigate functional, cognitive, physical and nutritional outcomes in adults with intellectual disabilities (IDs), comparing individuals with and without Down syndrome from São Paulo, Brazil, and to evaluate the associations of group, degree of disability, age and sex with these outcomes. Additionally, we hypothesized that individuals with Down syndrome would present greater vulnerability to cognitive and physical decline compared to those with ID of other aetiologies.\n\n\nMethod\nThis cross‐sectional observational study included 52 adults with ID divided into two groups: (1) 24 participants with Down syndrome (ID‐DS) and (2) 28 participants with non‐DS aetiologies (ID‐nonDS). Assessments included sociodemographic and clinical data; functional independence measure (FIM); physical performance (handgrip strength, 30‐s sit‐to‐stand test, gait speed test and MiniBESTest); nutritional status (Mini Nutritional Assessment [MNA]); cognitive function (Cambridge Cognitive Examination for Mental Disorders of the Elderly–Down Syndrome [CAMCOG‐DS]); cognitive decline (Informant Questionnaire on Cognitive Decline in the Elderly [IQCODE]); and functional activities (Pfeffer Questionnaire [QPAF]). Data were obtained through self‐report whenever possible, and proxy report (caregivers) when necessary, based on participants' communication abilities.\n\n\nResults\nCompared with the ID‐nonDS group, the ID‐DS group demonstrated significantly poorer learning (β = −2.56; p = 0.049) and remote memory performance (β = −1.18; p = 0.011), a nonsignificant trend towards lower handgrip strength (β = −4.68; p = 0.051) and more falls (β = −0.39; p = 0.050). Sex and degree of disability were associated with several outcomes, whereas age showed no significant effect.\n\n\nConclusion\nAdults in the ID‐DS group exhibited cognitive and physical profiles suggestive of increased vulnerability to age‐related functional impairment compared with adults with other forms of ID. These findings should be interpreted cautiously due to the cross‐sectional design and sample size limitations. Replication in larger samples will be necessary to confirm these observations.\n\n"]