A recent study by researchers at the University of Cambridge has revealed a strong link between the age at which autism is diagnosed and the likelihood of developing co-occurring mental health disorders.

By analyzing data from over 45,000 autistic individuals across Europe and the United States, the study found that timing of diagnosis may reflect underlying biological and developmental differences, which in turn affect long-term mental health outcomes.

Autism Spectrum Disorders (ASD) encompass a diverse group of conditions characterized by challenges in social interaction, communication, and behavior. These neurodevelopmental disorders manifest uniquely in each individual, with varying degrees of severity and impact on daily functioning.¹

It is estimated that worldwide in 2021 about 1 in 127 persons had autism.

According to the American Psychiatric Association's Diagnostic and Statistical Manual, Fifth Edition (DSM-5), a diagnosis of ASD requires:

• Persistent deficits in social communication and interaction across multiple contexts, manifested by:

  1. Deficits in social-emotional reciprocity

  2. Deficits in nonverbal communicative behaviors used for social interaction

  3. Deficits in developing, maintaining, and understanding relationships

• Restricted, repetitive patterns of behavior, interests, or activities, as manifested by at least two of the following:

  1. Stereotyped or repetitive motor movements, use of objects, or speech

  2. Insistence on sameness, inflexible adherence to routines, or ritualized patterns of verbal or nonverbal behavior

  3. Highly restricted, fixated interests that are abnormal in intensity or focus

  4. Hyper- or hyporeactivity to sensory input or unusual interest in sensory aspects of the environment

The study indicates that individuals diagnosed with autism before the age of six often exhibit stable, early-onset behavioral traits and distinct genetic profiles. These early-diagnosed individuals tend to have fewer co-occurring mental health conditions and may respond better to interventions that target developmental milestones from a young age.

In contrast, those diagnosed after the age of ten frequently show increasing social and behavioral difficulties during adolescence. This group is more likely to develop mental health challenges such as depression, anxiety, or other stress-related disorders. The findings suggest that later diagnoses may not only reflect delayed recognition but also indicate a distinct form of autism with different biological and behavioral patterns.

Diagnosing ASD typically involves:

1. Developmental Monitoring: Regular observation of a child's growth and behavior during routine health visits.

2. Developmental Screening: Formal assessments at 18 and 24 months to identify potential developmental delays.

3. Comprehensive Diagnostic Evaluation: Conducted by specialists, this includes:

   • Clinical interviews with caregivers

   • Standardized diagnostic tools (e.g., ADOS-2, ADI-R)

   • Observations of the child's behavior

   • Review of developmental history and medical records

The study highlights that autism is not a singular condition but a spectrum with varying developmental and genetic trajectories. Genetic analyses revealed that individuals diagnosed later in life share genetic signatures with conditions such as ADHD, depression, and post-traumatic stress disorder, while early-diagnosed individuals show genetic patterns more specific to classic autism.

These insights challenge the conventional view of autism as a single disorder and underscore the need for a nuanced understanding of the condition across different age groups.

Early diagnosis of autism is critical for improving developmental outcomes and mental health. Recognizing the diverse presentations of autism allows healthcare providers to tailor interventions that address both behavioral and emotional needs. Timely support can reduce the risk of secondary mental health problems and improve the overall quality of life for individuals on the spectrum.

The study emphasizes that a one-size-fits-all approach to autism is insufficient. Personalized strategies based on age at diagnosis, genetic profiles, and behavioral assessments are key to ensuring that interventions are effective and supportive throughout an individual’s life.

This Cambridge-led research provides important insights into how the age of autism diagnosis can influence mental health outcomes.

References:

1.World Health Organization. "Autism Spectrum Disorders." Last modified September 17, 2025. https://www.who.int/news-room/fact-sheets/detail/autism-spectrum-disorders.

2.Centers for Disease Control and Prevention. "Clinical Testing and Diagnosis for Autism Spectrum Disorder." Last modified May 8, 2025. https://www.cdc.gov/autism/hcp/diagnosis/index.html.

3. Zhang, Xinhe, Jakob Grove, Yuanjun Gu, Cornelia K. Buus, Lea K. Nielsen, Sharon A. S. Neufeld, Mahmoud Koko, Daniel S. Malawsky, Emma M. Wade, Ellen Verhoef, Anna Gui, Laura Hegemann, et al. “Polygenic and Developmental Profiles of Autism Differ by Age at Diagnosis.” Nature 1 October 2025. https://www.nature.com/articles/s41586-025-09542-6

(Rh/ARC/MSM)