To test a hypothesis that a biological mechanism could be at play, clinical psychologist Dr Kim Felmingham and her colleagues at the University of Tasmania set up a study to investigate whether women experienced greater release of stress hormones, which in turn led to greater consolidation and recall of emotional memories.
The study involved 80 healthy volunteers who were split into two groups with similar numbers of men and women. Participants were shown neutral and negative images, the latter usually images of victims of injury or violence.
Immediately after they viewed the images, half the participants were exposed to a stressor designed to raise arousal levels, which was holding their hands in ice water for three minutes.
The control group placed their hands in warm water instead. Participants’ cortisol levels were measured before and after. Two days later they returned and were asked to write down all the images they could remember.
Cortisol levels increased at similar levels in both men and women in the ice water group; however, only the women recalled significantly more negative images than the control group.
“We had actually predicted that maybe the women would respond more, so they would have higher arousal to the stressor, but we really didn’t see that at all… men and women had the same increase in levels of cortisol,” Dr Felmingham explains.
There were other unexpected results. In contrast to the ‘stressed women’, the women in the control group actually recalled fewer negative images than did the men.
When cortisol levels rose in the men, it significantly predicted their ability to recall the neutral images, rather than the negative ones.
“If you’ve got higher arousal, you are going to remember things more,” Dr Felmingham says. “What we are seeing is that women’s emotional memory systems tend to be more sensitive to that of the same arousal level as men.”
Other factors may also be contributing, she adds.
“There’s an increasing level of interest in the menstrual phase because we know it actually affects cortisol and stress hormones [for example]”, she says.
The study will also need to be tested in patients with diagnosed anxiety disorders.
“What I would expect is that we would see a greater elevation in arousal in women in a clinical population more so than here,” Dr Felmingham says.
If the findings do hold up, cortisol can most likely be modified with relaxation or mindfulness or other stress reduction techniques.
“A potential implication here is we try to train women in arousal reduction techniques,” she says. But first, more research is required.
As first appeared in Medical Observer. Source: Biol Psychol 2012; 89(3):539-44