Patient advocates have welcomed new research that appears to substantiate long-held concerns about systemic biases in the understanding and diagnosis of autism spectrum conditions. A landmark study indicates that the historical gender discrepancy in autism diagnoses may stem more from diagnostic shortcomings than from a genuine difference in prevalence between males and females.
Major Swedish Study Challenges Established Assumptions
Researchers from the Karolinska Institutet in Sweden conducted a comprehensive analysis of autism diagnosis rates among individuals born in Sweden between 1985 and 2020. The study, which tracked an impressive 2.7 million people, found that 2.8% received an autism diagnosis between the ages of two and 37. Crucially, the data revealed that by the age of 20, diagnosis rates for men and women had become almost equal.
This finding directly challenges the longstanding assumption that autism is significantly more common among males. Dr Caroline Fyfe, the study's lead author, explained: "Our findings suggest that the gender difference in autism prevalence is much lower than previously thought, due to women and girls being underdiagnosed or diagnosed late."
Significant Age Disparities in Childhood Diagnosis
The research uncovered striking disparities in the timing of diagnoses. During childhood, boys were diagnosed on average nearly three years earlier than girls, with median ages of 13.1 for boys compared to 15.9 for girls. Under the age of 10, boys were three to four times more likely than girls to receive an autism diagnosis.
However, the study noted that girls experienced a rapid increase in autism diagnoses during adolescence, effectively "catching up" by their twenties. The authors emphasised the importance of investigating why female individuals receive diagnoses later than their male counterparts.
Changing Patterns Over Time
Published in the prestigious BMJ journal, the study also examined trends over the last three decades. While gender disparities in diagnosis rates remained relatively consistent for children under 10, they decreased rapidly for all other age groups. The authors observed: "Findings indicate that the male to female ratio for autism spectrum disorder has decreased over time and with increasing age at diagnosis."
They further noted that in Sweden, the gender ratio may no longer be distinguishable by adulthood, suggesting the actual prevalence difference is substantially lower than previously believed.
Systemic Biases in Diagnostic Practices
In a linked editorial, patient advocate Anne Cary argued that the research supports the view that systemic biases in diagnosis, rather than a genuine gap in incidence, explain the historical discrepancy in diagnosis rates. While acknowledging that delayed symptom onset and masking behaviours undoubtedly play a role, Cary suggested that diagnostic methods and tools themselves might be biased and require refinement.
"These biases have meant that a girl who would ultimately have a diagnosis of autism would have a less than third of a chance of receiving a diagnosis before the age of 10 years," Cary added. She warned that while awaiting proper diagnosis, autistic girls and women are likely to be misdiagnosed with psychiatric conditions, particularly mood and personality disorders, forcing them to self-advocate for appropriate recognition and treatment.
Charity Responses and Calls for Change
Autism charities have responded to the findings by calling for urgent action to address gender stereotypes in diagnostic practices. Dr Judith Brown, head of evidence and research at the National Autistic Society, stated: "Gender should never be a barrier to receiving an autism diagnosis and access to the right support."
She explained that historically, it was wrongly assumed autistic people were mostly men and boys, but we now understand that women and girls are more likely to 'mask' traditional signs of autism, making identification more challenging. "Misdiagnosed autistic women can develop coexisting mental health difficulties, such as anxiety and depression, as a result of a lack of support and the exhaustion of masking," Dr Brown added.
Jolanta Lasota, chief executive of Ambitious about Autism, emphasised that autistic girls have different experiences to autistic boys and have slipped under the radar for far too long. By having their needs misunderstood or explained away as something else, she noted, they have missed vital support and sometimes reached crisis points with their mental health.
Clinical Perspectives and Service Implications
Dr Conor Davidson, former Royal College of Psychiatrists' autism champion and clinical lead for Leeds autism diagnostic service, provided important clinical context. "Autism in girls is more likely to go undetected during childhood and signs of the condition might only surface during adolescence or even early adulthood," he observed.
Dr Davidson noted that psychiatrists working in adult neurodevelopmental clinics in the UK have started seeing higher numbers of women than men coming forward in recent years. However, he highlighted the concerning reality of unacceptably long waiting lists for both child and adult autism assessments across the country.
"There are many autistic women who have not received a diagnosis, and it is vital that they are able to access a timely assessment and care if they need it," he stressed. Dr Davidson also emphasised the importance of psychiatrists considering autism when assessing patients with mental health problems, particularly for women whose autism may not have been identified during childhood.
The study's findings underscore the pressing need for diagnostic services to develop better understanding of how autism presents differently in girls and women, and for support services to adapt accordingly to meet the needs of this historically overlooked population.
