Timing of diagnosis, depression and self-harm in adolescents with autism spectrum disorder.

The autism diagnosis came from parent report and was not externally validated in the cohort. Depression and self-harm were measured at age 14 only, so the study cannot show how mental health changed over time. The Short Mood and Feelings Questionnaire has not been validated among adolescents with autism. Around 90% of children with autism in the sample had cognitive ability within the typical range. Results may not apply to children with autism who have cognitive delays or cannot complete self-report. Children excluded from the analysis had more cognitive delay, higher autism-related behaviours and were more likely to be in earlier diagnosed groups. This selection pattern may bias estimates. The study cannot prove that earlier diagnosis caused lower depression or self-harm. It did not measure mechanisms such as support, school placement or bullying. There were few girls with autism, limiting analysis of sex differences.

The authors declared no conflicts of interest. Funding was from the UK Economic and Social Research Council and the Japan Foundation for Paediatric Research; the funder named was the ESRC National Centre for Research Methods, University of Southampton.

Do not conclude that earlier diagnosis prevents depression or self-harm. The study is observational and only shows an association; it did not test whether moving diagnosis earlier changes outcomes, and children diagnosed at different ages may differ in access to support, school placement or other factors.