Autism Spectrum Disorders and Low Mental Age: Diagnostic Stability and Developmental Outcomes in Early Childhood
Some children with autism spectrum disorders (ASDs) exhibit low mental age (Low-MA; i.e., cognitive functioning below 12 months). We examined diagnosis, symptom severity, and development in children with ASD-low MA (n = 25), autistic disorder (n = 111), and PDD-NOS (n = 82) at ages two and four. We predicted that some ASD-low MA children would demonstrate just intellectual impairment and not autism symptoms on follow-up, with social deficits at age two attributable to global delays. Instead, most ASD-low MA children (96%) had an ASD at follow-up, compared to children initially diagnosed with autistic disorder (86.5%) or PDD-NOS (73.2%). They showed the least developmental progress and highest symptom severity. Results support diagnosing ASDs in children functioning below a 12-month level.
KeywordsAutism spectrum disorders Low mental age Developmental growth Diagnostic stability Autism severity
The authors wish to thank the families and clinicians who participated in the current study, as well as the Early Detection Study research team at the University of Connecticut for their assistance with data collection.
This study was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (Grant number R01HD039961) and the Maternal and Child Health Bureau (Grant number R40MC00270).
AH participated in conception of the study design, data collection, performance of statistical analyses, and drafting of the manuscript; LM participated in performance of statistical analyses, interpretation of the data, and revising of the manuscript; DF participated in conception of the study design, data collection, interpretation of the data, and revising of the manuscript. All authors read and approved the final manuscript.
Compliance with Ethical Standards
Conflict of interest
Deborah Fein is part owner of M-CHAT-R, LLC, which receives royalties from companies that incorporate the M-CHAT-R into commercial products and charge for its use. Data reported in the current paper is from the freely available paper versions of the M-CHAT and M-CHAT-R. Alexander Hinnebusch and Lauren Miller declare that they have no conflicts of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
- American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders (4th ed., text rev.). Washington, DC: Author.Google Scholar
- Berry, L. N. (2009). Early treatments associated with optimal outcome in children with autism spectrum disorders. Storrs: University of Connecticut.Google Scholar
- Charman, T., Taylor, E., Drew, A., Cockerill, H., Brown, J. A., & Baird, G. (2005). Outcome at 7 years of children diagnosed with autism at age 2: Predictive validity of assessments conducted at 2 and 3 years of age and pattern of symptom change over time. Journal of Child Psychology and Psychiatry, 46(5), 500–513.CrossRefPubMedGoogle Scholar
- Klin, A., Carter, A. S., & Sparrow, S. S. (1997). Psychological assessment of children with autism. In D. J. Cohen & F. R. Volkmar (Eds.), Handbook of autism and pervasive developmental disorders (2nd ed.) (pp. 418–427). New York: Wiley.Google Scholar
- Lord, C., Risi, S., Lambrecht, L., Cook, E. H. Jr., Leventhal, B. L., DiLavore, P. C., et al. (2000). The autism diagnostic observation schedule–generic: A standard measure of social and communication deficits associated with the spectrum of autism. Journal of Autism and Developmental Disorders, 30(3), 205–223.CrossRefPubMedGoogle Scholar
- Luyster, R., Guthrie, W., Gotham, K., Risi, S., DiLavore, P., & Lord, C. (2009). The autism diagnostic observation schedule–toddler module: preliminary findings using a modified version of the ADOS, (pp. 15–17). West Hartford: International Meeting for Autism Research.Google Scholar
- Moore, V., & Goodson, S. (2003). How well does early diagnosis of autism stand the test of time? Follow-up study of children assessed for autism at age 2 and development of an early diagnostic service. Autism: The International Journal of Research and Practice, 7(1), 47–63.Google Scholar
- Mullen, E. M. (1995). Mullen scales of early learning. Circle Pines, MN: American Guidance Service, Inc.Google Scholar
- Robins, D. L., Fein, D., Barton, M. L., & Green, J. A. (2001). The modified checklist for autism in toddlers: An initial study investigating the early detection of autism and pervasive developmental disorders. Journal of Autism and Developmental Disorders, 31(2), 131–144.CrossRefPubMedGoogle Scholar
- Rutter, M., Le Couteur, A., Lord, C., & Faggioli, R. (2005). ADI-R: Autism diagnostic interview–revised: Manual. OS, Organizzazioni speciali. Torrance: Western Psychological ServicesGoogle Scholar
- Sparrow, S. S., Balla, D. A., & Cicchetti, D. V. (1984). The Vineland adaptive behavior scales-interview edition. Circle Pines, MN: American Guidance Service.Google Scholar
- Sparrow, S. S., Cicchetti, D. V., & Balla, D. A. (2005). Vineland adaptive behavior scales (2nd edn.). Circle Pines, MN: American Guidance Services.Google Scholar
- Sutera, S., Pandey, J., Esser, E. L., Rosenthal, M. A., Wilson, L. B., Barton, M., Green, J., Hodgson, S., Robins, D. L., Dumont-Mathieu, T., & Fein, D. (2007). Predictors of optimal outcome in toddlers diagnosed with autism spectrum disorders. Journal of Autism and Developmental Disorders, 37(1), 98–107.CrossRefPubMedGoogle Scholar