Researchers have poured cold water on the idea that people with increased testosterone have reduced empathy.
The study was motivated by the fact that five times as many males as females are diagnosed with autism. “Of course, the primary suspect when we have something that is sharply differentiated by sex is testosterone,” said Dr Gideon Nave at the University of Pennsylvania, who led the study.
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One theory for this sex difference in autism diagnosis is that autism represents an exaggeration of ‘male’ tendencies, characterised by a thinking style that’s geared more towards systemising than empathising.
This ‘extreme male brain’ hypothesis has been supported by previous studies that found a connection between increased testosterone and reduced cognitive empathy – the capacity to read the emotions of others, which is characteristically impaired in people with autism. However, these studies were limited by small sample sizes, and the difficulty of determining a direct link.
In this new study – the largest of its kind – Nave and colleagues recruited 643 healthy men, giving them either an application of testosterone gel or a placebo.
The men’s empathy levels were then measured using questionnaires and behavioural tasks. In one task, they were shown a photo of an actor’s eyes and asked to select the emotional state that best matched the actor’s expression.
But the researchers found no evidence for a link between testosterone levels and empathy.
“Our results unequivocally show that there is not a linear causal relation between testosterone exposure and cognitive empathy,” said Dr Amos Nadler at Western University in Canada, the first author of the study.
However, this doesn’t rule out the possibility that testosterone could be related to empathy in a more indirect way.
“It seems that if testosterone does have an influence, the effect is complex, not linear,” said Nave. Meanwhile, the sex difference in autism diagnosis remains something of a mystery.
“For now, I think we have to embrace our ignorance on this,” said Nave.