Sex differences in fear conditioning and extinction

Females have a known vulnerability to developing anxiety disorders. Greater fear conditioning and impaired fear extinction are proposed underlying mechanisms of anxiety disorder development. The aim of the current study was to examine sex differences in fear conditioning, extinction and reinstatement of fear whilst controlling for levels of sex hormones. It was anticipated that females, tested when their estrogen and progesterone is low, would have reduced fear conditioning but impaired fear extinction, compared to males. Skin conductance and ratings of threat expectancy were recorded for 36 undergraduates who underwent a differential fear conditioning, extinction and reinstatement paradigm. Results suggest there were no sex differences in the overall magnitude of fear acquisition and extinction for SCR amplitude. However, males displayed greater generalised SCR amplitude at the start of extinction, and more rapid fear SCR reduction in this phase, though not only to the feared stimulus, and greater reinstatement of fear for SCR amplitude. On the other hand, females displayed greater threat expectancy ratings in the acquisition, extinction, and reinstatement phases. These findings are broadly consistent with previous literature and highlight an interesting differential response between SCR and cognitive threat expectancy between males and females during fear conditioning, extinction and reinstatement.