Study finds age at autism diagnosis could indicate one’s tendency for mental health disorders

The age at which autism is diagnosed could reflect differences in biology and development of a child, with a diagnosis in late childhood increasing chances of mental health disorders such as depression, according to a study.

Autism is a neurodevelopmental disorder which affects brain regions, including the cerebellum and amygdala, leading to impaired social and emotion management skills in an individual. Symptoms such as not responding to one’s name and not making eye contact can emerge in the first year of life or up to age two.

Researchers, including those at the University of Cambridge in the UK, have identified distinct patterns in the genes and development of those diagnosed in early childhood and those diagnosed later, typically from late childhood onwards.

The study, published in the journal Nature, looked at two groups with differing behaviour and genetic profile. In one group, difficulties in social interaction, and anxiety and hyperactivity emerge early but remain stable while in the other, the difficulties increase during teenage years.

On average, those diagnosed in late childhood and onwards were also more likely to experience mental health conditions such as depression compared to those who received a diagnosis earlier in childhood, the researchers said.

“The earlier-diagnosed autism factor had a low ... genetic correlation with educational attainment, cognitive aptitude, ADHD and various mental-health and related conditions,” the authors wrote.

“The later-diagnosed autism factor showed a ... significantly higher genetic correlations with ADHD and a range of other mental health and related conditions, including depression, PTSD (post-traumatic stress disorder), childhood maltreatment and self-harm,” they said.

Data for the study was collected from studies published between 1998 and 2024, such as those in Google Scholar and PubMed, which is managed by the US National Institutes of Health.