Reduced male hormone exposure may be linked to autism-like traits in males, study suggests

A new study published in Frontiers in Child and Adolescent Psychiatry has challenged a long-standing theory about why more males than females are diagnosed with autism and excel in science, technology, engineering, and mathematics fields. Researchers found that, contrary to popular belief, reduced exposure to male hormones during early development in males might actually be linked to traits often associated with autism, such as heightened sensory sensitivity and specific talents. This suggests a need to rethink current understandings of brain development and its connection to these traits.

For many years, scientists have tried to understand why autism spectrum disorder is diagnosed more frequently in males. One prominent idea, known as the Extreme Male Brain Theory, proposed that higher levels of male hormones (androgens), during prenatal development lead to a “hyper-masculine” brain. This brain type, according to the theory, is characterized by a strong drive to understand systems and rules, sometimes at the expense of social skills and empathy. This theory has been used to explain both autism and the perceived male dominance in fields like science and technology, suggesting that an excess of male hormones might push the brain towards these traits.

However, recent evidence has started to raise questions about this idea, especially when looking at males with autism. Some studies have even indicated that males with autism might show fewer, not more, typically masculine characteristics. This inconsistency prompted researchers at Sophia University, led by Atsuko Saito, to explore whether the opposite of the Extreme Male Brain Theory might hold true: could reduced exposure to male hormones in males play a role in the development of autism-related traits?

Autism is sometimes seen alongside other conditions related to sex development and atypical gender identities, adding another layer of complexity to the question of hormones and brain development. The new study aimed to investigate this alternative possibility by examining groups of males who might experience reduced effects of male hormones during their early development.

“Among the authors’ acquaintances, individuals assigned male at birth with differences/disorders of sex development (DSDs) or sexual minority identities were occasionally observed to exhibit neurodevelopmental traits and exceptional talents, such as artistic abilities,” explained Shintaro Tawata, the first author of the study. “Additionally, the author’s personal experience with gender dysphoria motivated their interest in exploring the co-occurrence mechanisms between gender diversity and neurodevelopmental conditions.”

To investigate this, the researchers compared three groups of adult males: individuals with Klinefelter syndrome, sexual minorities, and a control group. Klinefelter syndrome is a genetic condition in males where they are born with an extra X chromosome (XXY instead of XY). This condition is often associated with lower levels of testosterone, especially after puberty, and some researchers believe that these individuals might have experienced reduced androgen activity even earlier in development.

Sexual minorities, in this study referring to individuals not identifying as heterosexual, were included because previous research suggests that some indirect markers of early androgen exposure, like finger length ratios and childhood play preferences, appear more feminized in gay men and male-to-female transgender individuals. The control group consisted of men who did not have Klinefelter syndrome and identified as heterosexual and cisgender (meaning their gender identity aligns with the sex they were assigned at birth).

The researchers recruited participants from hospitals, clinics, support groups, and through online platforms. For the Klinefelter syndrome group, 22 men participated. For the sexual minority group, 66 men participated. The first control group, used for initial comparisons, included 36 men. Later, a second, larger control group of 583 men was recruited to re-examine some findings.

All participants completed online questionnaires. These questionnaires measured several things: synesthesia, a condition where senses are blended (like seeing colors when hearing sounds); savant tendency, which refers to exceptional skills in specific areas, often alongside developmental conditions; sensory hypersensitivity or hyposensitivity, meaning experiencing senses more or less intensely than typical; and different aspects of sexuality, including sexual orientation and gender identity.

The researchers also asked about childhood play preferences to indirectly assess early masculinity. They analyzed the data to see if there were significant differences between the groups in these measured traits and how these traits related to each other.

The researchers found that men in the sexual minority group reported higher rates of synesthesia compared to the large control group. Individuals in both the sexual minority group and those with Klinefelter syndrome scored higher on a scale that measured unusual sensory sensitivities. In other words, they were more likely to experience heightened or reduced sensory input—an attribute linked in past studies to autism spectrum disorder.

The sexual minority group also showed elevated savant tendencies, such as unusual numerical or musical skills, stronger memories for certain stimuli, or advanced language talents. A key insight was that these traits were most common among participants who also felt some degree of discomfort with their assigned male identity. Men who identified as having gender dysphoria scored higher on a measure of sensory sensitivity and were more likely to report synesthesia. They also tended to show more of the cognitive traits often discussed under the umbrella of savant abilities, suggesting that gender identity might overlap in complex ways with brain development.

“Synesthesia, savant tendencies, and sensory hypersensitivity/hyposensitivity were notably prominent among individuals with gender dysphoria,” Tawata told PsyPost. “This suggests a possible shared mechanism between neurodevelopmental conditions and gender dysphoria in shaping aspects of self-concept.”

A central takeaway is that, at least among males at birth, low rather than high prenatal testosterone may play a part in shaping autism-related traits. This challenges the popular idea that a hypermasculine brain causes these traits. While some earlier studies do suggest that excess androgen activity during development can be linked to autism characteristics in females, the pattern may differ in males.

The current study supports the idea that variation in hormone effects can move in more than one direction to influence traits such as sensory perception and social-cognitive style. The authors offer a possible explanation involving disrupted systems for certain brain chemicals like gamma-aminobutyric acid (GABA) and oxytocin. These disruptions may lead to an imbalance in how neurons fire and form connections, which in turn could alter how people sense the world around them, how they develop their sense of self, and even how they experience empathy toward others.

“The study provides significant insights that challenge the conventional theory attributing autism primarily to early developmental sex hormone excess,” Tawata explained. “It also suggests a higher likelihood of individuals with neurodiversity or differences in sex development possessing ‘potentially advantageous traits,’ such as synesthesia and savant abilities, in addition to sensory sensitivities. These findings may contribute to deeper self-understanding and societal awareness of sexual minorities and neurodivergent individuals, fostering their empowerment.”

As with all research, the study carries a few limitations. For one, the sample of participants with Klinefelter syndrome and those identifying as a sexual minority was relatively small, so it may not capture the full breadth of experiences in these populations. Another point is that the surveys relied on self-reports. While this can be an excellent tool for collecting large amounts of data, it does require further confirmation, perhaps through direct cognitive testing or physiological measures that might detect subtle differences in hormonal activity.

“It is important to note that not all transgender individuals exhibit sensory hypersensitivity or savant abilities,” Tawata noted. “Similarly, individuals outside this group can also display strong sensory sensitivities or exceptional abilities, as indicated by distribution data. It is crucial to avoid overgeneralization, as it can lead to harmful misconceptions and reinforce stereotypes. Additionally, some limitations in sampling and methodology exist, highlighting the need for further research using diverse samples and approaches to verify these findings.”

Going forward, the team hopes to deepen our knowledge of how gender identity, sex chromosomes, and hormone exposure connect with specialized traits in perception and cognition.

“This line of research aims to contribute to the understanding of the mechanisms underlying neurodevelopmental conditions and gender dysphoria, while also contributing to deeper self-understanding and societal awareness of sexual minorities and neurodivergent individuals, fostering their empowerment,” Tawata said. “Furthermore, clarifying the multifaceted nature of perception, cognition, and the mechanisms underlying savant abilities is expected to contribute to improved educational and developmental support for individuals with neurodiversity.”

“Most existing literature on Klinefelter syndrome and other sex chromosome anomalies focuses on language difficulties, learning disabilities, and communication deficits. This study is significant in highlighting the presence of individual strengths. Additionally, while individuals with DSDs are often assumed to live according to their assigned gender role, the study makes visible the existence of a subset of this group that experiences gender dysphoria and its association with variations in perception and cognition.”

The study, “Androgyny and atypical sensory sensitivity associated with savant ability: a comparison between Klinefelter syndrome and sexual minorities assigned male at birth,” was authored by Shintaro Tawata, Kikue Sakaguchi, and Atsuko Saito.