Developmental Trajectories of Autistic Traits in Infants With Autism and/or ADHD Family History: Predictors and Mid-Childhood Outcomes
PURPOSE: Autism is both a developmental and heterogeneous condition, with individual variation in the timing and shape of autistic symptom trajectories over time, as recognised by the concept of 'chronogeneity'. Prospective infant autism family history studies are well-suited to examining developmental trajectory variability, a key aspect of autism trait heterogeneity. METHODS: We examined autistic trait trajectories in a large sample of infants with autism and/or ADHD family history (N = 384) followed from infancy to mid-childhood. Using group-based multi-trajectory modelling, we identified classes with distinct trajectories across three autism trait measures taken at six, five, and four timepoints, respectively, between 5 months and 9 years. RESULTS: A 5-class solution provided the best fit. Three classes included 50-75% children meeting autism diagnostic criteria at 3 years or mid-childhood, with distinct differences in timing, onset, and developmental patterns of autistic traits. Two classes were predominantly typically developing, with one characterised as 'slow starters'. Background characteristics including autism/ADHD family history, sex, maternal education, and household income (but not ethnicity) predicted class membership. Mid-childhood outcomes-IQ, adaptive function, autism and ADHD traits, anxiety and behavioural difficulties-differed across trajectory classes. CONCLUSION: The timing and developmental course of autistic traits-independent of trait level-relate meaningfully to infant and family characteristics, diagnostic timing, and mid-childhood outcomes. These findings support chronogeneity as a valuable framework for understanding autism heterogeneity in family history studies. The trajectory classes identified here are descriptive; future studies should examine their replicability, and explanatory and mechanistic value.
Authors
- Mayada Elsabbagh (ORCID: https://orcid.org/0000-0002-7311-9059)
- Elizabeth Shephard (ORCID: https://orcid.org/0000-0002-5952-3565)
- Greg Pasco (ORCID: https://orcid.org/0000-0003-0290-6124)
- Kenny Chiu (ORCID: https://orcid.org/0000-0001-8776-9864)
- Helen Maris
- Luke Mason (ORCID: https://orcid.org/0000-0001-9978-7349)
- Laura Pirazzoli
- Sarah Lloyd‐Fox (ORCID: https://orcid.org/0000-0001-6742-9889)
- Tony Charman (ORCID: https://orcid.org/0000-0003-1993-6549)
- Bosiljka Milosavljevic (ORCID: https://orcid.org/0000-0001-9590-0869)
- Michelle Liew
- Mark Henry Johnson (ORCID: https://orcid.org/0000-0003-4229-2585)
- Isobel Gammer
- Erica Salomone (ORCID: https://orcid.org/0000-0002-8083-5942)
- Louise O’Hara
- Leila Dafner
- Sarah Kalwarowsky (ORCID: https://orcid.org/0009-0009-3817-0244)
- Emily J. H. Jones (ORCID: https://orcid.org/0000-0001-5747-9540)
- Tessel Bazelmans (ORCID: https://orcid.org/0000-0001-9623-0473)
- Jannath Begum Ali (ORCID: https://orcid.org/0000-0002-8853-0537)
- Kim Davies (ORCID: https://orcid.org/0000-0001-6407-8999)
- Rianne Haartsen (ORCID: https://orcid.org/0000-0003-1072-4152)
- PF Bolton
- Teodora Gliga (ORCID: https://orcid.org/0000-0001-8053-7286)
- Chloë Taylor
- Janice Fernandes
- Helena Ribeiro
- L Tucker
- Rowan Arthur
- Anna Blasi
- Anna Kolesnik
- Laurel Fish
- Jeni Baykoca
- The BASIS/STAARS Team
- Andrew Pickles
- Jeanne Guiraud
- Celeste Cheung
- Mia Medas
Institutions
- King's College London (GB)
- University of Cambridge (GB)
- Birkbeck, University of London (GB)
Publication Details
- Journal
- Journal of Autism and Developmental Disorders
- Published
- 2026-08-25
- DOI
- https://doi.org/10.1007/s10803-026-07481-3
- Primary Topic
- Autism Spectrum Disorder Research
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Autism Speaks
- Autistica
- Maudsley Charity
- European Federation of Pharmaceutical Industries and Associations
- Government of the United Kingdom
- UK Research and Innovation
- Simons Foundation Autism Research Initiative
- Guy's and St Thomas' Charity
- European Commission
- HORIZON EUROPE Framework Programme
- Medical Research Council
- Staatssekretariat für Bildung, Forschung und Innovation
- HORIZON EUROPE European Innovation Council