Testosterone Improves Brain Response to Threat in Men

The brain's response to threat increases in men who take testosterone, a steroid hormone, a new research shows.

The research team led by, researcher Dr. Justin Carré, assistant professor at Nipissing University, looked into the brain structures that are involved in threat processing and aggressive behavior. These areas are the amygdala, hypothalamus and periaqueductal grey.

Past researches have shown that doses of testosterone increase the brain circuit function in women. For the current study, the researchers aimed to find out whether testosterone also increases response to threat cues in male brains.

For the study, the researchers examined 16 healthy young men. They were tested over two days. Participants were given placebos on one test day and testosterone the other day. However, all the subjects were given a drug that suppressed their testosterone on both test days.

The study results showed that testosterone improved reactivity of the amygdala, hypothalamus and periaqueductal grey when participants viewed angry facial expressions.

"We were able to show for the first time that increasing levels of testosterone within the normal physiological range can have a profound effect on brain circuits that are involved in threat-processing and human aggression," explained Carré. "Understanding testosterone effects on the brain activity patterns associated with threat and aggression may help us to better understand the 'fight or flight' response in males that may be relevant to aggression and anxiety," Dr. John Krystal, the Editor of Biological Psychiatry, said in a press release.

According to the researchers, understanding how testosterone influences the male brain is important as testosterone enhancement products are gaining popularity rapidly, especially among aging men experiencing reduced virility.

"Our current work is examining the extent to which a single administration of testosterone influences aggressive and competitive behavior in men," Carré concluded.

The findings are published in the journal Biological Psychiatry.