# Urban–Rural Differences and Sex‐Specific Cognitive Effects on Autism Symptom Trajectories: A Longitudinal Study of Autistic Children in Taiwan

## TL;DR

This study tracked 180 autistic children in Taiwan over 9 years and found that autism symptoms changed with age differently based on where they lived, their sex, and their IQ.

## Contribution

The study provides new longitudinal insights into autism symptom development in a non-Western context, highlighting urban–rural and sex-specific differences.

## Key findings

- Children from urban areas had higher baseline restricted and repetitive behaviors and smaller increases in social-affect symptoms compared to rural children.
- Higher IQ, especially verbal IQ, was linked to fewer social challenges over time, but this effect was stronger in girls than in boys.
- Children diagnosed under DSM-5 had lower initial symptoms but showed greater increases in total and social-affect symptoms over time compared to DSM-IV-diagnosed children.

## Abstract

Few longitudinal studies have mapped autism symptom trajectories outside Western contexts. This study aimed to characterize trajectories of autism symptoms, assessed using the Autism Diagnostic Observation Schedule (ADOS), and associated child and family factors among autistic children from two regions in Taiwan that differ by urbanicity. Another aim was to examine the time‐varying effects of children's cognitive abilities on autism symptoms, which remain understudied due to prior reliance on baseline proxies. Children with a confirmed autism diagnosis (n = 180, 87.8% male) were followed across three waves of data collection from ages 2 to 11 years. Linear multilevel growth models with random intercepts and slopes were used to estimate symptom trajectories at the total and domain levels of the ADOS. On average, total and social‐affect symptoms increased significantly with age, while restricted and repetitive behaviors (RRBs) remained stable. Children from urban areas showed higher baseline RRBs and smaller increases in social‐affect symptoms compared to those from rural areas. Additionally, children diagnosed under DSM‐5 criteria showed lower baseline symptoms but greater increases in total/social‐affect symptoms over time than their DSM‐IV counterparts. A sex interaction effect was observed in the time‐varying associations between IQ (particularly verbal IQ) and total/social‐affect symptoms, with girls showing stronger negative IQ‐symptom associations. These findings highlight the developmental complexity underlying the manifestation of autism symptoms, particularly at the intersection of sex and cognition. The distinct patterns by urbanicity also underscore the need to mitigate urban–rural disparities in service access to better support autistic children's long‐term outcomes.

This study followed 180 autistic children in Taiwan over 9 years and found that autism symptoms changed with age in ways that varied by children's place of residence, sex, and IQ. Children from rural areas showed greater increases in social difficulties, whereas those from urban areas showed higher levels of restricted and repetitive behaviors. Higher IQ was associated with fewer social challenges over time—but only among girls, not boys. These findings highlight the need to consider both individual and environmental factors, such as the child's cognitive abilities, sex, and urban–rural contexts, when assessing and supporting the long‐term development of autistic children.