The transition from reproductive age to menopause is a major milestone in the female lifecycle. It is a hormonal process with a very clear end result: a menopausal state—though its commencement is gradual and vague. It is unavoidable and perfectly normal. The age of the transition varies widely, a fact that hints at the possibility that the reproductive clock is individualized, ticking at a diversified pace. Therefore, the study of the menopausal transition may actually be a derivative of the study of reproduction because it marks the closing of that chapter in a woman's life.

In a sequential approach, the period of transition is defined as perimenopause, or the menopausal transition, the beginning of the second phase in the life of the adult woman, characterized by a stable, low level of gonadal steroids, as opposed to the cyclic fluctuations during the reproductive phase. This imposed, though anticipated, closing of the reproductive chapter of life is often associated with mixed feelings.

As reviewed by Andrea Riccardo Genazzani, MD, PhD, and colleagues, gonadal steroids exercise a profound effect on many body systems, including the brain, in which they have specific receptors, influencing neurotransmitters and other central nervous system (CNS) mechanisms that are considered to be involved in the regulation of mood, cognition, and behavior. Therefore, it would be anticipated that the menopausal decrease in activity levels of female gonadal hormones, ie, estrogen and progesterone, resulting in substantial changes in mood, cognition, and behavior of menopausal women—but this is not the case. This fact illuminates two issues of social and clinical significance: Menopause, per sé, is a normal healthy situation, and even though it is normal it is characterized by age-related processes that may be slowed down or delayed by gonadal steroids.