Using positron emission tomography to investigate hormone-mediated neurochemical changes across the female lifespan: implications for depression.

Ovarian hormones, particularly oestrogen and progesterone, undergo major fluctuations across the female lifespan. These hormone transition periods, such as the transition from pregnancy to postpartum, as well as the transition into menopause (perimenopause), are also known to be times of elevated susceptibility to depression. This study reviews how these transition periods likely influence neurochemical changes in the brain that result in disease vulnerability. While there are known associations between oestrogen/progesterone and different monoaminergic systems, the interactions and their potential implications for mood disorders are relatively unknown. Positron Emission Tomography (PET) allows for the in-vivo quantification of such neurochemical changes, and, thus, can provide valuable insight into how both subtle and dramatic shifts in hormones contribute to the elevated rates of depression during pre-menstrual, post-partum, and perimenopausal periods in a woman's life. As one better understands how to address the challenges of PET studies involving highly vulnerable populations, such as women who have recently given birth, one will gain the insight necessary to design and individualize treatment and therapy. Understanding the precise time-line in younger women when dramatic fluctuations in the hormonal milieu may contribute to brain changes may present a powerful opportunity to intervene before a vulnerable state develops into a diseased state in later life.