Trajectories in Symptoms of Autism and Cognitive Ability in Autism From Childhood to Adult Life: Findings From a Longitudinal Epidemiological Cohort

Abstract

Objective: For the first time, we use a longitudinal population-based autism cohort to chart the trajectories of cognition and autism symptoms from childhood to early adulthood and identify features that predict the level of function and change with development. Method: Latent growth curve models were fitted to data from the Special Needs and Autism Project cohort at three time points: 12, 16, and 23 years. Outcome measures were IQ and parent-reported Social Responsiveness Scale autism symptoms. Of the 158 participants with an autism spectrum disorder at 12 years, 126 (80%) were reassessed at 23 years. Child, family, and contextual characteristics obtained at 12 years predicted intercept and slope of the trajectories. Results: Both trajectories showed considerable variability. IQ increased significantly by a mean of 7.48 points from 12 to 23 years, whereas autism symptoms remained unchanged. In multivariate analysis, full-scale IQ was predicted by initial language level and school type (mainstream/specialist). Participants with a history of early language regression showed significantly greater IQ gains. Autism symptoms were predicted by Social Communication Questionnaire scores (lifetime version) and emotional and behavioral problems. Participants attending mainstream schools showed significantly fewer autism disorder symptoms at 23 years than those in specialist settings; this finding was robust to propensity score analysis for confounding. Conclusion: Our findings suggest continued cognitive increments for many people with autism across the adolescent period, Q6 but a lack of improvement in autism symptoms. Our finding of school influences on autism symptoms requires replication in other cohorts and settings before drawing any implications for mechanisms or policy.

A Meta-analysis of Outcome Studies of Autistic Adults: Quantifying Effect Size, Quality, and Meta-regression

“…et al (2014) found that autistic adults without intellectual disability were less likely to live independently or to have obtained employment compared to non-autistic adults with intellectual disability. Social factors, such as attendance in mainstream schooling may also exert an influence on outcome, potentially more so than IQ (Simonoff et al 2019). These studies suggest that behavioural, cognitive, or social factors not necessarily associated with IQ may affect outcome.…”

Reported autism diagnosis strongly predicts psychotic-like experiences in the Adolescent Brain Cognitive Development cohort

“…First, we compared participants with and without ASD across the variables described above. For continuous variables, we compared means with Welch’s two-sided unequal variances t -test, and for categorical variables we compared frequency counts with Pearson’s χ 2 . Within each of these sets, we used the Benjamini-Hochberg procedure to control the false discovery rate.…”

“…Autism spectrum disorder (ASD) and schizophrenia (SCZ) are separate diagnostic entities that in some respects show clear divergence. ASD, typically diagnosed in childhood, is characterized by the combined presence of social communication deficits and restricted or repetitive behaviors 1 and tends either to have a stable course or to show clinical improvement with time 2 . SCZ, typically diagnosed in late adolescence or early adulthood 3 , is characterized by psychosis, which reflects a loss of contact with reality, and manifests as delusional beliefs or hallucinatory experiences 4 .…”

Associations between theory of mind and conduct problems in autistic and nonautistic youth

“…A total of 100 autistic adolescents and 57 nonautistic adolescents who had an IQ ≥ 50, were assessed as part of the Special Needs and Autism Project (SNAP) cohort (see Baird et al, 2006 for details). Participants were recruited at 12 years and followed up in adolescence and young adulthood (Simonoff et al, 2020). Here we report upon data from adolescence (mean age 16 years) (see Charman et al, 2011 for details).…”