# Latent trajectories in autistic individuals: A systematic review

## TL;DR

This review summarizes how autistic individuals develop over time in different domains, highlighting the need for more research on understudied areas like motor coordination and sleep.

## Contribution

The paper systematically reviews longitudinal subtyping of autism characteristics and identifies gaps in current research.

## Key findings

- Autistic individuals show distinct developmental patterns in core characteristics and other domains.
- Lower cognitive development is linked to more severe core autism symptom trajectories.
- Motor coordination and sleep problems are understudied in autism trajectory research.

## Abstract

Autism is heterogenic in core and co-occurring characteristics. Subtyping autism in a longitudinal manner aids the understanding of autism development throughout life and thus enhances personalized support. In this systematic review, we summarized the literature on latent core autism characteristics trajectories and trajectories of other functional domains in autistic individuals and identified predictors of trajectory assignment. We searched Embase, Medline, PsycINFO, Cochrane Central, Web of Science, and Google Scholar until April 22, 2025. We included longitudinal observational studies that applied statistical subtyping methods on core autism characteristics or other functional domains in autistic individuals. A total of 30 eligible analyses were included. The included analyses investigated core autism characteristics (10), adaptive behavior (10), behavioral problems (7), adverse childhood experiences (1), cognitive development (1), and feeding problems (1). For each domain, we found differing numbers and shapes of trajectories. Cognitive development was predictive of core autism symptom trajectory classifications, where cognitive development was generally lower in more severely affected core autism symptom trajectories. We found mixed results for other predictors. Future studies should focus on understudied outcome domains, such as motor coordination or sleep problems. In addition, more research is needed to understand when and why individuals deviate from their subgroup trajectory.

Autistic people can have very different characteristics. Investigating groups based on their characteristics over time can improve our understanding of how autistic people develop and why development can differ between people. We reviewed studies that group autistic individuals based on their development of autistic features and other characteristics. We included 30 analyses and summarized their findings. The studies show that there are different ways autistic individuals develop based on core autistic characteristics (social difficulties and focused, intense and repetitive behaviors, interests and activities), as well as for adaptive behavior, behavioral problems, cognitive development, and feeding problems. For core characteristics, lower cognitive abilities seemed to be related to less favorable developmental pathways. This review showed that autistic people may show distinct patterns of development in core characteristics and other domains. We also highlight that some domains of functioning, such as motor coordination and sleeping problems, are not studied in the literature and future studies should focus on these domains as well since these are difficulties that autistic people often face. Identifying distinct developmental patterns in autistic children can help to predict the outcome of autistic people and may aid in offering personalized support.