In men, the fall in sex hormone production is much more gradual (then with women), developing over decades rather than months or years. Mental and physical changes can occur, but they are much more subtle in onset and can easily be missed.
As such, the term 'male menopause', or andropause, is probably not accurate. Instead, experts prefer to talk about 'partial androgen deficiency of the ageing male' (PADAM).
Production of testosterone (the principal male-determining sex steroid) falls gradually and progressively from the 40s onwards. Other hormones are also affected, including growth hormone, insulin-like growth factor-1 (IGF-1), parathyroid hormone and melanocyte-stimulating hormone. The significance of these changes is not well understood.
The symptoms of PADAM are numerous and non-specific, so it is not an easy condition to diagnose. They include problems with:
Circulation and the nervous system: hot flushes, sweating, insomnia, nervousness.
Mood and cognitive (higher mental) function: irritability and tiredness, decreased sense of well-being
lack of motivation, low mental energy, difficulty with short-term memory, depression, low self-esteem,
being easily frightened.
Masculinity and virility: decreased vigour and physical energy, diminished muscle strength.
Sexuality: decreased interest in or desire for sex, less sexual activity, poor erections, reduced quality of orgasm
weakness of ejaculation, reduced volume of ejaculated fluid.
Physical features include: diminished muscle mass, loss of body hair, abdominal obesity.