Testosterone in men does not necessarily bring down their cognitive empathy, reveals a new study, which challenges the idea that autism is an expression of an extreme male brain.
Earlier, the differentiating male hormone of testosterone was thought to be the culprit, but now it is not clear why men tend to show symptoms of autism, rather than women.
The study says that there does not seem to be any linear causal link between testosterone and cognitive empathy, or the ability to understand the feelings of others, which is rather less in people with autism.
Amos Nadler of Western University, author of the study said, "Several earlier studies have suggested a connection between testosterone and reduced cognitive empathy, but samples were very small, and it's very difficult to determine a direct link."
About 643 participants in the study were given an application of testosterone gel or a placebo. They filled in some questionnaires and fulfilled behavioural tasks. When they were given a photograph of the eyes of an actor, they were given options to select which emotional state described their expression.
Another interesting measure that was taken was the 2D:4D ratio, which included the length of the participant's second finger to their fourth finger.
Researchers found that administering the gel shot up the level of the hormone, but it did not impact the tests of cognitive empathy at all. Moreover, there was also no link at all between their performance on tests and their 2D:4D ratio.
It had been in 2011 that scientists found a link between testosterone and limited cognitive empathy. At that time, giving testosterone to healthy women brought down their empathetic performance. Hence, testosterone affected their performance.
The study was used to support the extreme male brain hypothesis of autism. Autism is an exaggeration of the male inclination towards a cognitive style, whose main features are "systemising over empathising".
However, the new researchers are clear that the earlier study looked into just 16 persons. Other studies were based on correlative, not causative evidence.
Gideon Nave, assistant professor of marketing in Penn's Wharton School, said, "The results are plain. However, it's important to note that the absence of evidence is not evidence of absence."
Even though there is not enough data that supports the impact of testosterone, it does not mean that there are no possible effects either. So if testosterone makes some impact, it paves the way for a complex, not linear effect. In real life, things don't really work out that way, he said.
This study was published in Proceedings of the Royal Society B: Biological Sciences.