Research has shown that stress has a different impact on both the sexes, which in turn may affect decision-making in different ways. However, the actual brain mechanism that is involved in this difference is still unclear. This study used brain scans to detect gender differences in stress related behavior specifically when right decision making may lead to a monetary reward. Results revealed that “stress led to greater reward collection and faster decision speed in males but less reward collection and slower decision speed in females.”
Studies have shown that stress induces changes such as risky behavior, improved decision making speeds, improved response to rewards and also learning to get more rewards. It has also been seen that men and women react differently to stress. While men tend to take more risks and win more rewards when placed under stress, women are known to do just the opposite. Still, the exact gender differences in male and female brains that lead to such characteristic behavior under stress are unknown. This study attempted to use brain scans to analyze the differences in the brains of the two sexes when subjected to stressors that could earn them monetary rewards.
* For this study, a total of 24 healthy males and 23 healthy females were chosen. Of these, 12 men and 11 women were placed in the stressed group.
* Two types of stressors were applied. The first involved placing the participant’s hand in ice cold water for up to three minutes. The second stressor was to take part in a decision-making task that, if played correctly, would bring monetary rewards.
* The second stressor was given only to the designated 12 men and 11 women in the stressed group. The rest performed an ordinary non-stressful task.
* Brain scans using fMRI (Functional Magnetic Resonance Imaging) were performed for all participants during the tests.
* The cold stress was seen to double the levels of the body’s stress hormone, called cortisol, indicating adequate induction of stress. This cold stress exposure did not affect decision-making and brain images in participants who were given an ordinary task.
* However, among those given the decision-making task, males made decisions faster and got more rewards while women were slower and got fewer rewards. Risk-taking was low in all the studied participants.
* The risky decision-making task in men and women resulted in differential activation of various parts of the brain including “striatum and anterior insula”.
Authors admit that their study results deviated from original findings of other studies that have shown that men exhibit more risky behavior than women when asked to perform stressful decision-making tasks. This study did not show high risk behavior in either of the sexes. Authors speculate that it could be due to the task modification that the researchers made in order to accommodate the brain scans in the study. They suggest further studies to examine the differences in behavior when placed under stress.
This study is the first of its kind that looks at brain scans of individuals faced with a complex decision-making test under stress that provided monetary rewards. This study reveals that cold stress changed decision making in a sex-specific manner. Also, areas of the brain such as the dorsal striatum and the anterior insula were seen to be activated differently in males and females when exposed to a stressful task. On exposure to stress, while decision-making speed improved in men, it deteriorated in women. The actual answer to the question why these gender differences exist is still not answered and authors speculate, “Addressing this question is likely to require consideration of individual effects of social environment, genetics, sex hormones, development and their interactions.”
For More Information:
Gender Differences in Reward-related Decision Processing under Stress
Publication Journal: Social Cognitive and Affective Neuroscience, May 2011
By Nichole R Lighthall; Michiko Sakaki
From the University of Southern California, Los Angeles, California
*FYI Living Lab Reports Are Summaries of the Original Research.