New research has challenged the controversial Extreme Male Brain (EMB) theory, which posits that excess exposure to testosterone in the womb inhibits the development of cognitive empathy in both males and females, thereby acting as a possible trigger for autism.
Cognitive empathy is the ability to interpret the emotional state of others and understand their subsequent behaviours. This ability is often lacking in people with autism, and is distinct from emotional empathy which concerns the ability to vicariously feel another’s emotions. Poor cognitive empathy abilities are linked to an array of other psychopathological conditions like psychopathy, borderline personality disorder, and schizophrenia.
Males are four times as likely as females to have autism according to the US Centers for Disease Control, but the reason for this is unknown.
EMB theory: hormone-driven orientation towards systemizing
The EMB theory gained popularity over the last decade via the work of British researcher Simon Baron-Cohen. He contends that autistic people are hardwired to think and act in stereotypically male extremes, like possessing a strong interest in system analysis, because of prenatal exposure to high levels of testosterone. Conversely, they are lacking in stereotypically female traits such as cognitive empathy.
The theory has been criticized for relying on binary, outdated assumptions about gender, as well as the questionable quality of research supporting it.
In their experiments, Baron-Cohen and his colleagues found that women issued a strong dose of testosterone performed worse in an RMET (Reading the Mind in the Eyes Test), which involves participants interpreting the emotions of others based on facial expressions. Separate studies that supported the theory were criticized for their small sample sizes, and small-scale follow-up studies failed to replicate the findings, yet the idea still gained traction in some circles.
This inspired the lead author of the present study, Amos Nadler from the University of Toronto, and colleagues to act: “People referred to that original study as if it was a solid stepping stone,” he said in an interview with Science. “Pardon my French, but nobody was calling bullshit.”
No linear link to testosterone’s effects found in adults
The team’s goal was to debunk the idea that giving people testosterone as adults influences their cognitive empathy abilities.
As such, they investigated using a much larger sample size by recruiting 643 healthy adult males to take part in two randomized trials in which the subjects were dosed with either testosterone or a placebo. Participants then completed questionnaires and underwent RMET testing, but no statistically significant difference was found in the test results between the placebo group and the group who received testosterone.
Senior author Gideon Nave caveated that the book is not closed. Just because they found no linear interaction doesn’t mean a complex interaction couldn’t exist: “It’s important to note that the absence of evidence is not evidence of absence,” said Gideon when interviewed by Penn Today.
“We found that there is no evidence to support this effect of testosterone, but that doesn’t rule out any possible effects. From what we know, though, it seems that if testosterone does have an influence, the effect is complex, not linear. Reality is typically not that simple.”
Directly addressing the question of whether high levels of prenatal testosterone lead to autism or empathy issues is beyond the scope of this study. It would require researchers to sample the hormone in utero and follow up with children and their parents years later, but taking these samples could endanger the developing fetus.
Still, one of Nadler’s hopes is that the results will help to curb people from preemptively running with the idea that if we control testosterone levels, we can control autism — for example, by inhibiting the hormone in pregnant women via medication.
“If there’s no relationship, then we shouldn’t give people false hope,” he says.