Menopause is the permanent cessation of menstrual cycles after the loss of ovarian follicular activity. It can be spontaneous (natural menopause) or iatrogenic (secondary menopause). The latter includes the removal of both ovaries (surgical menopause), chemotherapy or radiotherapy.
Factors that influence menopause
The functional life expectancy of the human ovaries is determined by a complex but largely unidentified set of genetic, hormonal and environmental factors. Women experience menopause when the ovarian follicles have already been exhausted. However, the clinical manifestations of menopause are the result of dynamic interactions between neuroendocrine changes and alterations of the reproductive endocrine axis that command ovarian function. The reason why the ovaries begin their function at puberty and stop it at menopause is not clear. The understanding of this phenomenon would be of great value for reproductive and health problems.
The time of menopause reflects a complex interaction of genetic, epigenetic, socioeconomic and lifestyle factors. Estimates of the inheritance of the age of menopause range from 30% to 85%. Almost 50% of the variability in the age of menopause among individuals is related to genetics. Women whose mothers or other first-degree relatives had an early menopause are 6-12 times more likely to have an early menopause. On the other hand, cross-sectional and cohort studies have shown that the age of menopause is closely associated with the age at which the mother experienced menopause. However, so far, genetic studies have failed to clearly identify the underlying genetic traits that would intervene in inheritance.
Symptoms of menopause
Most women who enter menopause experience vasomotor symptoms. A hot flash is a sudden episode of vasodilation in the face and neck, which lasts 1-5 minutes and is accompanied by profuse sweating. Women who suffer from these hot flashes have a narrower thermoneutral zone, so that subtle changes in central temperature cause thermoregulatory mechanisms, such as vasodilation, sweating or chills. The decrease in estrogen and inhibin B levels, as well as the increase in FSH levels, explain only part of the thermoregulation disorder, which is associated with changes in brain neurotransmitters and peripheral vascular reactivity
Hot flashes occur at the end of perimenopause and the first years of postmenopause. Some women, however, may continue to experience vasomotor symptoms until many years after menopause. Occasionally, hot flashes occur at the end of the reproductive years, or several years after menopause. The onset and intensity of menopausal symptoms vary widely among women and depend on genetic, environmental, racial, lifestyle and anthropometric factors. The black race, smoking and overweight – in particular, central obesity – increase the prevalence and severity of vasomotor symptoms.