“Women develop these anxiety disorders at approximately twice the rate that men do and we really don’t have a good explanation for why that happens,” says Felmingham.
Anxiety disorders include Post Traumatic Stress Disorder (PTSD), panic disorder, generalised anxiety disorder, major depression and social phobia.
The common symptoms of anxiety disorders are those of arousal, such as heightened heart rate and fear reactions, feeling jumpy, trembling, sweaty or panicky.
People with anxiety also tend to have intrusive and negative thoughts, and catastrophic predictions, which maintains this arousal. In PTSD this can mean having images of the trauma coming back or imagining another trauma.
Some have argued that anxiety disorders appear to be more common in women because they are more comfortable talking about it, but Felmingham says while this might be true, it does not explain the gender gap.
Felmingham and colleagues tested a biological hypothesis that could explain why women have a greater prevalence of anxiety disorders.
Previous research has found emotional memories, typically negative memories, are better recalled than neutral emotions, says Felmingham.
And, the higher the arousal at the time the emotional memory is encoded dictates how well it is “consolidated” and remembered later.
“Maybe women have greater arousal during encoding and that therefore leads to stronger emotional memory consolidations,” says Felmingham.
She and colleagues investigated this hypothesis in about 80 healthy men and women.
They measured the stress hormone cortisol in saliva samples of the participants before and after they were shown either neutral or negative images.
The negative images were typically of injury or violence – such as guns or assault victims with bruised faces or bloodied bodies.
Immediately after viewing the images, at the time their emotional memory was being consolidated, half the participants were asked to hold their hands in ice water for three minutes, to increase their arousal.
The other half put their hands in warm water, to act as a control group.
Two days later, the participants were asked to write down all the images they could remember.
Both men and women in the aroused group showed greater cortisol levels and recalled negative images better than neutral.
But despite having the same level of arousal as men, the women in this group recalled a significantly greater number of negative images than in the control group.
“With that same level of arousal, women actually had greater memory consolidation than men,” says Felmingham.
Felmingham says it is not clear what specifically about the arousal that is affecting memory recall but the findings suggest a potential mechanism for the greater prevalence of anxiety disorders in women.
The current study was carried out in healthy volunteers and Felmingham says the next step is to extend the study to people who actually suffer from anxiety disorders.
As first appeared in ABC Online, 17 July 2012