In men, hair loss and baldness occurs as a result of the male hormone ‘dihydrotestoterone’ (DHT) shrinking hair follicles over time, in a process known as follicular miniaturisation. Eventually new hairs stop growing, which results in baldness. DHT also activates female pattern baldness.
The main difference between men and women, is that the ‘pattern’ of thinning is different: in women the tends to be a scattered thinning over the top of the scalp, and the frontal hairline is usually preserved. Men however, tend to lose hair at the crown and frontal hairline (so called recession).