Some men aren't troubled by this at all. Others, however, suffer great emotional distress associated with a lack of self-esteem and, in some cases, depression.

Pattern baldness is often inherited and can affect men and women. It is caused when hair follicles are oversensitive to the hormone dihydrotestosterone (DHT), produced by the male hormone, testosterone. DHT causes the follicles to shrink and eventually stop functioning. Both men and women produce this hormone in different amounts.

The involvement of testosterone in balding has led to the myth that going bald is a sign of virility. But men with male-pattern baldness don't have more male hormones than other men. Their hair follicles are simply more sensitive to the hormones.

Receding hairline

Male-pattern baldness is so called because it tends to follow a set pattern. The first stage is usually a receding hairline, followed by thinning of the hair on the crown and temples.

When these two areas meet in the middle, it leaves a horseshoe shape of hair around the back and sides of the head. Eventually, some men go completely bald.

Male-pattern baldness is not a disease, so it won't affect your health. However, if it's causing you distress, consult your doctor to get a diagnosis.

Your doctor can refer you to a dermatologist for further analysis and, if necessary, to a counsellor to help with the trauma of hair loss.

If you have inherited the genes responsible for male-pattern or female-pattern baldness there's little you can do to prevent it from happening.

Treatments can slow down the process, but there's no cure. The two most effective treatments for male-pattern baldness (also called 'androgenetic alopecia') are medicines called minoxidil and finasteride.

Other treatments for hair loss include wigs, hair transplants and plastic surgery procedures, such as scalp reduction.

As a general rule, it's easier to maintain existing hair than to regrow it, and once the hair follicle has stopped working it cannot be revived.