For years, autism spectrum disorder (ASD) has been predominantly associated with boys and men. However, recent studies have begun to challenge this perception, suggesting that girls and women may be underdiagnosed. This article explores the growing body of evidence that suggests a gender gap in autism diagnosis.
Is Autism Diagnosed in Females More Than Males?
No. While there has been a perception that ASD is more prevalent in one of the genders, recent studies suggest that there may be a gender gap in diagnosis rather than a difference in prevalence.
Gender Disparity in Autism Diagnoses
Studies have suggested that the true male-to-female ratio of children meeting the criteria for ASD is closer to 3:1, highlighting a potential diagnostic gender bias. This bias means that girls who meet ASD criteria may be at risk of not receiving a clinical diagnosis, leading to the underrepresentation of females in official autism statistics.
Gender |
Autism Diagnosis Ratio |
Male |
4:1 |
Female |
3:1 |

Diagnostic Bias in Autism
Studies have shown that girls with autism may exhibit higher levels of social ability compared to boys, which could potentially hinder a full ASD diagnosis. This discrepancy raises important questions about the impact of biases in diagnosing sex-specific presentations of autism and whether there are true sex differences in prevalence.
Despite ongoing efforts to address biases in autism diagnosis and referral processes, the 3-to-1 sex ratio between boys and girls with autism persists. This consistent ratio, even after repeated screenings for autism from infancy, suggests that there are likely inherent biological or genetic factors influencing the gender gap in autism diagnoses.
Factors Influencing Diagnosis
Several factors play a crucial role in the identification and assessment of the condition. Understanding these factors is essential for accurate and timely diagnosis, especially considering the disparities in diagnosis between genders.
Intelligence Levels and Diagnosis
Intelligence level is a significant factor that can influence the sex ratio of ASD prevalence. Studies indicate that males are often over-represented among high-functioning ASD cases. This discrepancy in the sex ratio may stem from ascertainment bias, where co-occurring intellectual disability might increase the likelihood of females receiving an ASD diagnosis, while high-functioning females may remain undiagnosed.

Symptom Presentation Differences
Research has highlighted that males tend to exhibit more externalizing behavior problems such as aggression, hyperactivity, and repetitive behaviors. In contrast, females with ASD often display more internalizing symptoms like anxiety, depression, and emotional struggles. These variations in symptom presentation suggest that behaviors typically associated with males may be more disruptive, leading to a higher likelihood of evaluation and diagnosis for boys.
Social Ability and Diagnosis
A study revealed that a lower proportion of high-functioning girls meet the full diagnostic criteria for ASD compared to boys. This discrepancy suggests that higher levels of social ability in females might hinder a complete ASD diagnosis. This finding raises questions about whether the prevalence of ASD skewed towards males is influenced by diagnostic biases related to sex-specific symptom presentations or genuine differences in prevalence based on gender.
Genetic and Biological Factors
It becomes evident that there are factors that contribute to the differences in diagnosis between genders. These factors play a crucial role in understanding why autism prevalence varies between males and females.
Heritable Mutational “Load”
Recent genetic studies have shed light on the concept of the heritable mutational “load” in ASD. It has been suggested that females with ASD may carry a higher heritable mutational “load” compared to males. This higher mutational burden in females may place relatives of female probands at an increased risk for ASD. These findings support the existence of female-protective factors within the genetic architecture of ASD.
Genetic Studies on Female ASD
Another factor is how genes are expressed. This means how genes turn on or off. Studies have found that people with ASD, especially females, have different gene expression patterns in their brains. For example, certain genes related to brain immune cells might be expressed differently in girls with ASD compared to boys. This could mean that girls and boys need different genetic factors to develop ASD symptoms.
Historical and Contemporary Trends
Unraveling the evolution of autism diagnosis trends can also provide insights into the shifting landscape of autism prevalence across genders. Understanding the changing sex ratios and the impact of detection improvements is essential.
Changing Sex Ratios Over Time
The sex ratio for autism diagnosis has exhibited fluctuations over the years, reflecting advancements in diagnostic practices and awareness. A 1995 Danish study initially reported a striking 8-to-1 ratio of boys to girls diagnosed with autism. However, by 2010, this ratio had significantly decreased to 3-to-1. This marked transition is largely attributed to enhanced capabilities in detecting autism among girls, illuminating a previously overlooked population within the autism spectrum.
Detection Improvements Impacting Ratios
A comprehensive analysis of data from 54 prevalence studies worldwide in 2017 underscored this imbalance, revealing approximately 4.2 boys diagnosed with autism for every girl. Notably, when focusing on the 20 studies where participants were directly evaluated for autism, the male-to-female ratio was reduced to 3.25 boys per girl. This nuanced difference underscores a diagnostic bias that has historically hindered the identification of autism in girls.
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Sources:
https://pubmed.ncbi.nlm.nih.gov/28545751
https://www.thetransmitter.org/spectrum/autisms-sex-ratio-explained/