ASD symptoms emerging early tend to decline with age but may persist for some

Symptoms of autism spectrum disorder (ASD) that emerge early manage to decrease as a person grows older, but impairment persists in adulthood for some, a study has found. Furthermore, other individuals develop autistic symptoms across adolescence and adulthood.

“This challenges our current understanding that ASD symptoms inevitably first manifest early in development,” the authors said.

No population-based prospective studies investigating the natural history of autistic symptoms from childhood to adulthood have been conducted thus far. To address this, the current study characterized the development and heterogeneity of such symptoms in a population-based cohort from childhood up to age 25 years.

The authors analysed data in a prospective UK population-based cohort (ALSPAC) and derived trajectories using five assessments of the parent-rated Social and Communication Disorders Checklist (SCDC) spanning ages 7–25 years. They also used additional measures to validate these symptom trajectories.

Three discrete SCDC symptom trajectory classes were recognized, namely low (88.5 percent), declining (5.0 percent), and late-emerging (6.5 percent). Both the declining and late-emerging trajectory classes correlated with child and adult ASD measures, low IQ, communication problems, peer problems, and worse adult functioning compared with the low trajectory class.

Of note, male sex showed an inclination toward a higher likelihood of being in the declining trajectory class (odds ratio [OR], 2.84, 95 percent confidence interval [CI], 2.19–3.69). This sex difference did not manifest in the late-emerging class (OR, 1.00, 95 percent CI, 0.80–1.24) as compared with the low trajectory class.

“ASD is currently considered an early-onset neurodevelopmental condition,” the authors said. “Follow-up studies of clinic-ascertained autism suggest that autistic symptoms typically decline with age, although symptom improvement is limited for some.”