Research for sex differences in fear extinction

Abstract

Fear memory has an important role in survival, but excess fear memory could be cause to fear-related disorders such as post traumatic disorder (PTSD). People who undergo a fearful event do not always develop PTSD, suggesting that there are vulnerable factors to develop the disorder. It is believed that sex, in particular female, is one of the factors as it is known that the prevalence rate of PTSD is higher in women than in men. However, the biological mechanisms underlying the sex differences in their prevalence rate remain unclear. Because previous studies reported that patients with fear-related disorders show an impairment of fear extinction, investigation of sex differences in fear extinction may be useful for understanding the greater vulnerability of women to fear-related disorders. Although number of papers investigating sex differences in fear extinction, these reports have increased recently. This review introduces fear extinction, sex differences in fear extinction is low, and the molecular mechanisms of sex differences in fear extinction. In the molecular mechanisms, we focused brain-derived neurotrophic factor (BDNF)-tropomyosin-related kinase B (TrkB) receptor signal which has been investigated by independent research groups.