Date:September 23, 2015
Source:Université de Montréal
Summary:Women react differently to negative images compared to men, which may be explained by subtle differences in brain function. This neurobiological explanation for women’s apparent greater sensitivity has been demonstrated by researchers in a new study.
“Not everyone’s equal when it comes to mental illness,” said Adrianna Mendrek, a researcher at the Institut universitaire en santé mentale de Montréal and lead author of the study. “Greater emotional reactivity in women may explain many things, such as their being twice as likely to suffer from depression and anxiety disorders compared to men,” Mendrek added, who is also an associate professor at the University of Montreal’s Department of Psychiatry.
In their research, Mendrek and her colleagues observed that certain areas of the brains of women and men, especially those of the limbic system, react differently when exposed to negative images. They therefore investigated whether women’s brains work differently than men’s and whether this difference is modulated by psychological (male or female traits) or endocrinological (hormonal variations) factors.
For the study, 46 healthy participants — including 25 women — viewed images and said whether these evoked positive, negative, or neutral emotions. At the same time, their brain activity was measured by brain imaging. Blood samples were taken beforehand to determine hormonal levels (e.g., estrogen, testosterone) in each participant.
The researchers found that subjective ratings of negative images were higher in women compared to men. Higher testosterone levels were linked to lower sensitivity, while higher feminine traits (regardless of sex of tested participants) were linked to higher sensitivity. Furthermore, while, the dorsomedial prefrontal cortex (dmPFC) and amygdala of the right hemisphere were activated in both men and women at the time of viewing, the connection between the amygdala and dmPFC was stronger in men than in women, and the more these two areas interacted, the less sensitivity to the images was reported. “This last point is the most significant observation and the most original of our study,” said Stéphane Potvin, a researcher at the Institut universitaire en santé mentale and co-author of the study.
The amygdala is a region of the brain known to act as a threat detector and activates when an individual is exposed to images of fear or sadness, while the dmPFC is involved in cognitive processes (e.g., perception, emotions, reasoning) associated with social interactions. “A stronger connection between these areas in men suggests they have a more analytical than emotional approach when dealing with negative emotions,” added Potvin, who is also an associate professor at the University of Montreal’s Department of Psychiatry. “It is possible that women tend to focus more on the feelings generated by these stimuli, while men remain somewhat ‘passive’ toward negative emotions, trying to analyse the stimuli and their impact.”
This connection between the limbic system and the prefrontal cortex appeared to be modulated by testosterone — the male hormone — which tends to reinforce this connection, as well as by an individual’s gender (as measured be the level of femininity and masculinity). “So there are both biological and cultural factors that modulate our sensitivity to negative situations in terms of emotions,” Mendrek explained. “We will now look at how the brains of men and women react depending on the type of negative emotion (e.g., fear, sadness, anger) and the role of the menstrual cycle in this reaction.”
- Ovidiu Lungu, Stéphane Potvin, Andràs Tikàsz, Adrianna Mendrek. Sex differences in effective fronto-limbic connectivity during negative emotion processing. Psychoneuroendocrinology, 2015; 62: 180 DOI: 10.1016/j.psyneuen.2015.08.012
Jan. 7, 2013 — Red wine could give athletes and players a boost in the sports arena by increasing the amount of performance-enhancing hormone testosterone in their bodies, according to researchers from London’s Kingston University.
However not only could the beverage help them to trophy success, it could also allow them to beat anti-doping tests. A team led by Professor Declan Naughton, from the University’s School of Life Sciences, found that red wine might reduce the amount of testosterone excreted by the body, which could distort the findings of drug tests taken from urine samples.
Testosterone is a naturally-occurring steroid hormone present in both men and women. It can increase muscle mass, boost stamina and speed up recovery. Sportspeople, however, are prohibited from taking it, or a synthetic version of it, to try to gain a competitive edge.
Although red wine is not a banned substance away from the sports field, Professor Naughton’s team has referred its findings to the World Anti-Doping Agency because of the newly-discovered side effect of potential change to the amount of testosterone in the body.
“Previous research has shown the effect over-the-counter anti-inflammatory drugs can have on enzymes,” Professor Naughton explained. “Since many of these drugs are derived from plants, we decided to look at the effect particular foods and beverages can have on enzymes involved in testosterone excretion. We chose green tea and then red wine because both have a huge variety of natural molecules and we wanted to see if they affected the amount of testosterone excreted in urine.”
The team found that a compound in red wine, known as quercetin, partially blocked the action of an enzyme called UGT2B17, which looks for testosterone and then sends a message to the kidneys to excrete it.
Professor Naughton stressed that the research had so far been conducted in test tube experiments and had yet to be trialled on humans. “A full clinical study would be needed to determine the effects on people but, if the same results were found, it would confirm that compounds in red wine can reduce the amount of testosterone in urine and give a boost to testosterone levels,” he explained.
The effect of red wine on an individual would vary because of factors such as weight, fitness, health and diet, making it hard to estimate how much was needed to improve performance, Professor Naughton said.
Teetotallers are not exempt from the effects. In fact, the alcohol content of red wine has very little impact because non-alcoholic molecules are responsible for inhibiting testosterone excretion.
The team also found the results were the same for red wine extract in supplement form. The active compounds such as quercetin are found in many foodstuffs as well as supplements.
The findings have been published in leading international journal Nutrition. The research follows an earlier study from Professor Naughton’s team which showed that green and white tea could also inhibit testosterone excretion.
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- Carl Jenkinson, Andrea Petroczi, Declan P Naughton. Red wine and component flavonoids inhibit UGT2B17 in vitro. Nutrition Journal, 2012; 11 (1): 67 DOI:10.1186/1475-2891-11-67