This study examines change in 152 children over an almost 10-year period (T1: 4.9 (± 1.3) years; T2: 8.1 (± 1.3) years; T3: 15(± 1.6) years) using a group-based, semi-parametric method in order to identify distinct developmental trajectories. Important deficits remain at adolescence in the adaptive abilities of children with Autism spectrum disorders, but changes in adaptive skills show two distinct growth rates. The univariate analysis reveals that low growth trajectories for both social and communication outcome are associated with the following characteristics at age 5: low cognitive and language skills, presence of epilepsy, and severity of autism. The multivariate analysis confirms that risk factors at age 5, were low language and severity of autism for both social and communication outcomes 10 years later, and that hours of early intervention was protective factor for communication.

Little is known about long‐term outcomes. We investigate the adaptive trajectories and their risk factors in ASD. Data were obtained from 281 children prospectively followed untill adulthood. The final sample consisted of 106 individuals. Vineland scores were collected at baseline (T1), 3 (T2), 10 (T3), and 15 (T4) years later. A group‐based method was used to identify homogeneous patterns of adaptive skills trajectories. Results show that among the children initially categorized as autistic, 82.6% remained over the ADOS diagnostic threshold, 11.9% converted to atypical autism, and 5.4% fell under the ADOS threshold. Most atypical autism diagnoses were unstable. Most (81.7%) autistic participants had an ID at inclusion. At T1, 59.3% were nonverbal, but only 39% at T4. Most changes occurred between 4 and 8 years of age. Approximately 25% of participants exhibited a “high” growth trajectory, in which progress continues throughout adolescence, and 75% a “low” growth trajectory, characterized by greater autistic symptoms, intellectual disability, and lower language abilities reflected by high CARS scores, low apparent DQ, and speech difficulties, which mostly, but not always, predicted low trajectories. Our findings suggest that the adaptive prognosis of autism is mostly poor in this cohort, biased toward intellectual disability. However, changes in diagnostic, speech, and adaptive status are not uncommon, even for indivduals with low measured intelligence or apparent intellectual disability, and are sometimes difficult to predict. Autism Research 2018, 11: 1455–1467. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. Lay Summary Most autism diagnoses given before 5 years of age are stable to adulthood, but one‐fifth of individuals are no longer considered to be autistic, even in a cohort biased toward apparent intellectual disability. Conversely, atypical autism diagnoses are mostly unstable. One‐third of children who are nonverbal at 5 years are verbal within 15 years, mostly before 8 years of age. Concerning adaptive behavior outcomes, only one‐fourth of children exhibit a high‐growth trajectory through at least 15 years.

Background: Autism spectrum disorder (ASD) is an early-onset and lifelong neurodevelopmental condition frequently associated with intellectual disability (ID). Although emerging studies suggest that ASD is associated with premature ageing and various medical comorbidities, as described for ID, data are scarce. Objectives: To determine the comorbidity burden and its association with distinct clinical presentation in terms of ASD severity, adaptive skills, level of autonomy, and drug exposure in a well-phenotyped sample of individuals with ASD-ID—the EFAAR (Frailty Assessment in Ageing Adults with Autism Spectrum and Intellectual Disabilities) cohort. Methods: A total of 63 adults with ASD-ID, with a mean age of 42.9 ± 15.1 years, were recruited from 2015 to 2017 from nine specialized institutions. They underwent detailed clinical examinations, including screening for comorbidities, ASD severity [Childhood Autism Rating Scale (CARS)], adaptive functioning [Vineland Adaptive Behavior Scale II (VABS-II)], autonomy [activities of daily living (ADLs)], and drug use [polypharmacy and the Drug Burden Index (DBI)]. The comorbidity burden was evaluated using the Cumulative Illness Rating Scale (CIRS-G) and its sub-scores [the severity index (CIRS-SI) and severe comorbidity (CIRS-SC)]. Results: We found a large range of comorbidities, including gastrointestinal disorders and mental and neurological diseases. Overall, 25% of our ASD-ID sample had chronic kidney disease with the associated increased cardiovascular risk factors. The comorbidity burden was high (mean CIRS-G total score of 10.6 ± 4.8), comparable with that observed among patients older than those in our population hospitalized in geriatric departments. Furthermore, the comorbidity burden positively correlated with age, decreased autonomy, and polypharmacy. Conclusion: The severity of the comorbidity burden associated with premature ageing in adults with ASD and ID highlight their crucial need of personalized medical care.