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
Date:September 22, 2015
Source:University of Illinois at Urbana-Champaign
Summary:A new study links anxiety, a brain structure called the orbitofrontal cortex (OFC), and optimism, finding that healthy adults who have larger OFCs tend to be more optimistic and less anxious.
The new analysis, reported in the journal Social, Cognitive and Affective Neuroscience, offers the first evidence that optimism plays a mediating role in the relationship between the size of the OFC and anxiety.
Anxiety disorders afflict roughly 44 million people in the U.S. These disorders disrupt lives and cost an estimated $42 billion to $47 billion annually, scientists report.
The orbitofrontal cortex, a brain region located just behind the eyes, is known to play a role in anxiety. The OFC integrates intellectual and emotional information and is essential to behavioral regulation. Previous studies have found links between the size of a person’s OFC and his or her susceptibility to anxiety. For example, in a well-known study of young adults whose brains were imaged before and after the colossal 2011 earthquake and tsunami in Japan, researchers discovered that the OFC actually shrank in some study subjects within four months of the disaster. Those with more OFC shrinkage were likely to also be diagnosed with post-traumatic stress disorder, the researchers found.
Other studies have shown that more optimistic people tend to be less anxious, and that optimistic thoughts increase OFC activity.
The team on the new study hypothesized that a larger OFC might act as a buffer against anxiety in part by boosting optimism.
Most studies of anxiety focus on those who have been diagnosed with anxiety disorders, said University of Illinois researcher Sanda Dolcos, who led the research with graduate student Yifan Hu and psychology professor Florin Dolcos. “We wanted to go in the opposite direction,” she said. “If there can be shrinkage of the orbitofrontal cortex and that shrinkage is associated with anxiety disorders, what does it mean in healthy populations that have larger OFCs? Could that have a protective role?”
The researchers also wanted to know whether optimism was part of the mechanism linking larger OFC brain volumes to lesser anxiety.
The team collected MRIs of 61 healthy young adults and analyzed the structure of a number of regions in their brains, including the OFC. The researchers calculated the volume of gray matter in each brain region relative to the overall volume of the brain. The study subjects also completed tests that assessed their optimism and anxiety, depression symptoms, and positive (enthusiastic, interested) and negative (irritable, upset) affect.
A statistical analysis and modeling revealed that a thicker orbitofrontal cortex on the left side of the brain corresponded to higher optimism and less anxiety. The model also suggested that optimism played a mediating role in reducing anxiety in those with larger OFCs. Further analyses ruled out the role of other positive traits in reducing anxiety, and no other brain structures appeared to be involved in reducing anxiety by boosting optimism.
“You can say, ‘OK, there is a relationship between the orbitofrontal cortex and anxiety. What do I do to reduce anxiety?'” Sanda Dolcos said. “And our model is saying, this is working partially through optimism. So optimism is one of the factors that can be targeted.”
“Optimism has been investigated in social psychology for years. But somehow only recently did we start to look at functional and structural associations of this trait in the brain,” Hu said. “We wanted to know: If we are consistently optimistic about life, would that leave a mark in the brain?”
Florin Dolcos said future studies should test whether optimism can be increased and anxiety reduced by training people in tasks that engage the orbitofrontal cortex, or by finding ways to boost optimism directly.
“If you can train people’s responses, the theory is that over longer periods, their ability to control their responses on a moment-by-moment basis will eventually be embedded in their brain structure,” he said.
- Sanda Dolcos et al. Optimism and the Brain: Trait Optimism Mediates the Protective Role of the Orbitofrontal Cortex Gray Matter Volume against Anxiety. Social, Cognitive and Affective Neuroscience, September 2015 DOI: 10.1093/scan/nsv106
- A Sekiguchi, M Sugiura, Y Taki, Y Kotozaki, R Nouchi, H Takeuchi, T Araki, S Hanawa, S Nakagawa, C M Miyauchi, A Sakuma, R Kawashima. Brain structural changes as vulnerability factors and acquired signs of post-earthquake stress. Molecular Psychiatry, 2012; 18 (5): 618 DOI: 10.1038/mp.2012.51
Date:September 14, 2015
Summary:Evidence of emotional load sharing between partners in a close relationship has bee uncovered by researchers. Their new study found that a strong relationship with a loved one can help ease stress when placed in difficult situations.
“We wanted to test a new evolutionary theory in psychology called Social Baseline Theory which suggests that humans adapted to be close to other humans,” says Ms. Lougheed. “The idea is that individuals function at a relative deficit when they are farther away from people they trust.”
In their study, Ms. Lougheed and co-authors measured the stress levels of 66 adolescent girls during a spontaneous speech task. Before the speech performance, the participants and their mothers rated the quality of their relationship. During the speeches, researchers tracked the participants’ level of stress via galvanic skin response (measuring the level of skin perspiration). To account for the effect of physical — rather than purely emotional — closeness, the participants’ mothers were instructed either to hold or not hold their daughters’ hand.
The researchers found that physical closeness allowed the participants to manage their stress more efficiently, regardless of how close the mother-daughter pair reported being. However, when physical contact was removed from the equation, only the participants who reported higher relationship quality showed signs of load sharing.
“Our results suggest that we are better equipped to overcome challenging situations when we are closer — either physically or in terms of how we feel in our relationships — to people we trust,” says Ms. Lougheed.
Participants who had reported the lowest level of mother-daughter relationship closeness and lacked physical contact during the task were the least efficient in managing emotional stress.
“We were somewhat surprised to find that mothers’ stress did not vary by physical closeness — after all, it can be stressful for parents to watch their children perform, but being able to offer physical comfort might have lessened the mothers’ stress,” says Ms. Lougheed.
“Thus, emotional load sharing in this context was not a function of the mothers’ stress level, and we expect that it occurred instead through the daughters’ perceptions of how stressful it was to give a speech. That is, higher physical and/or relationship closeness helped the daughters feel like they could overcome the challenging situation.”
The results suggest that physical contact can overcome some difficulties associated with relatively low relationship quality, or that being in a high-quality relationship is helpful for managing emotions in the same way as the physical comfort of a loved one. Lougheed does, however, note that the general level of relationship quality was relatively high in their sample, and that physical contact may function very differently in distressed families. She also cautions against generalizing these results to other partnerships — such as a relationship between romantic partners, platonic friends and other family members — and suggest that more research be done to determine the effect of socioeconomic status and gender, amongst other factors.
The study, “Sharing the burden: the interpersonal regulation of emotional arousal in mother-daughter dyads,” was published in the journal Emotion.
- Jessica P. Lougheed, Peter Koval, Tom Hollenstein. Sharing the Burden: The Interpersonal Regulation of Emotional Arousal in Mother−Daughter Dyads.. Emotion, 2015; DOI: 10.1037/emo0000105