Autism Rates in Girls and Boys May Be More Equal: A Swedish Study Challenges Long-Held Assumptions
Autism has long been viewed as a condition that predominantly affects male individuals, but a study from Sweden published by The BMJ challenges this assumption. The study reveals that autism may actually occur at comparable rates among male and female individuals, with a surprising twist: girls may be catching up to boys during adolescence.
The research, which analyzed diagnosis rates of autism for 2.7 million individuals born in Sweden between 1985 and 2022, found that while boys were more likely to be diagnosed with autism in childhood, girls caught up during adolescence, resulting in a male-to-female ratio approaching 1:1 by age 20. This finding highlights the need to investigate why girls receive diagnoses later than boys.
The prevalence of autism spectrum disorder (ASD) has increased over the past three decades, with a high male-to-female diagnosis ratio of around 4:1. This increase is attributed to factors such as wider diagnostic criteria and societal changes, such as parental age. However, the high male-to-female ratio has also been linked to better social and communication skills among girls, making autism more difficult to spot.
The study's authors acknowledge that they did not consider other conditions associated with autism, such as ADHD and intellectual disability, and were unable to control for shared genetic and environmental conditions like parental mental health. Despite these limitations, the study's size and duration enabled the researchers to link data for a whole population and disentangle the effects of three different time scales: age, calendar period, and birth cohort.
The findings indicate that the male-to-female ratio for autism has decreased over time and with increasing age at diagnosis. This suggests that the male-to-female ratio may be substantially lower than previously thought, and may no longer be distinguishable by adulthood in Sweden.
These findings align with recent research and seem to support the argument that current practices may be failing to recognize autism in many women until later in life, if at all, says Anne Cary, patient and patient advocate, in a linked editorial. She notes that studies like this are essential to changing the assumption that autism is more prevalent in male individuals than in female individuals.
However, Cary also points out that as autistic women await proper diagnosis, they are likely to be (mis)diagnosed with psychiatric conditions, especially mood and personality disorders. She emphasizes the importance of self-advocacy for autistic women to be seen and treated appropriately as autistic patients, just as their male counterparts.
