As Daniel Patrick Moynihan, an American sociologist, politician, and diplomat once said: “Everyone is entitled to his own opinion, but not his own facts”. And we wholeheartedly agree. A shared set of facts is the first step to building a better world with longevity for all. In that spirit, we are creating a series that covers 101 indisputable facts about ageing, health and longevity.
In terms of functional decline, the ovaries are both the earliest and the fastest ageing human organs. The ovaries begin to suffer a functional decline during a woman’s 20s, and for many, the ovaries are considered ‘geriatric’ by the standards of other organs by her late 20s/early 30s. The rate of ovarian ageing is quite variable from person to person, however, with some women remaining quite fertile up until the menopause. The quality of the oocytes declines with age, as does the number of follicles (the small sacs within the ovaries that release eggs), leading to irregularity of menstrual cycles culminating in the menopause, which occurs at a mean age of 51. Following this, follicle numbers decline sharply and ovulation stops.
Following the menopause, the ovaries stop producing oestrogen and progesterone, which are important in many processes besides development of secondary sexual characteristics during puberty. Absence of these hormones leads to an increased risk of multiple age-related diseases, particularly osteoporosis as both oestrogen and progesterone stimulate the activity of osteoblasts, the cells responsible for depositing new bone tissue in order to maintain bone mass. Women who experience the menopause later in life tend to live longer and have improved ability to repair their DNA on average.
Ovarian ageing is unusual in that its effects are felt relatively early in life, and women may need to plan their life choices around reproductive longevity. Our understanding of what drives ovarian ageing is still limited. We know that the menopausal age of a woman is predicted by that of her mother, suggesting that the rate of ovarian ageing has a genetic component, though estimates of heritability vary greatly. Changes in cell signalling, telomere shortening, oxidative stress and other common culprits of ageing have been observed to correlate with ovarian ageing.