Most people hold a number of misconceptions about the actual causes of hair loss. Some believe that they begin to loose hair when the blood supply to the head begins to reduce, others believe that a major cause of hair loss is the use of harmful soap or shampoos, frequently changing the brand of shampoo or soap used, washing hair using ‘soft’ water or even by brushing hair too frequently. Some believe that shaving of the scalp will regenerate hair growth, or in using miracle growth formulas; most of these causes and ‘cures’ are fallacies, and have been proven wrong by research.

Normally, hair loss is caused by genetic baldness and hormones. In most cases, an individual’s genetic makeup determines if hair follicles are sensitive to the chemical dihydrotestosterone (DHT), which causes them to shrink. This shrinkage results in overall thinning over time. Though this is an essentially universal change in all of us, a number of hormonal, genetic, or disease states make some of us lose hair earlier in life and in larger, more conspicuous quantities. The following is a general discussion on the various known causes for hair loss in both men and women.

Androgenetic Alopecia
One of the most common types of hair loss in both men and women is androgenetic alopecia, also known as male pattern baldness or female pattern baldness, and is related to hormone levels in the body. This particular cause of hair loss is related to a genetic tendency to lose hair, which may be inherited from the father or mother. Androgenetic alopecia affects roughly 50 per cent of men and perhaps as many women over the age of 40

The cause of hair loss in this condition is a chemical called dihydrotestosterone, or DHT, which is made from androgens (male hormones that all men and women produce) by the action of an enzyme called 5-alpha reductase. People with a lot of this enzyme make more DHT, which in excess can cause the hair follicles to make thinner and thinner hair until eventually they disappear completely. In men, the loss of hair follows a horseshoe-shaped pattern, withthe hair on the sides and

back of the headgenerally being left untouched. Women’s pattern of hair loss is different to the typical receding hairline and crown loss in men. Instead, androgenetic alopecia causes a general thinning of women's hair, with loss predominantly over the top and sides of the head.

One can assess chances of developing baldness by looking at male relatives, starting with fathers and grandfathers (especially the mother's father - if he has symptoms of male pattern baldness, a person is at high risk to develop the same symptoms). The male pattern baldness genes can come from the mother just as easily, but may be less noticeable since it's often slower to develop in women.

Alopecia Areata
Another important cause of hair loss is a condition called alopecia areata, an autoimmune disease (where the hair follicles are attacked by white blood cells), making the follicles small and slowing hair production dramatically, so there may be no visible hair growth for months and years. This results in the development of patches of baldness, usually in

small circular areas of the scalp. This disease usually affects young adults, and occurs equally in men and woman. After some time, hair may regrow as before, come back in patchy areas, or not regrow at all. A severe form of alopecia areata is the total loss of scalp hair (alopecia totalis) and even sometimes the complete loss of all body hair (alopecia universalis). About 33% of those afflicted with these rare problems will grow back all their hair within a year though, recurrences do occur.

Telogen Effluvium (Stress Trigger)
Another common form of hair loss is a condition called telogen effluvium, in which there is a widely spread out shedding of hair around the scalp and elsewhere on the body. This is usually a reaction to intense stress on the body's physical or hormonal systems, or as a reaction to medication. The condition can occur at any age and generally begins fairly suddenly and gets better on its own within about six months, although for a few people it can become a chronic problem.

Telogen effluvium is a phenomenon related to the growth cycles of hair. Hair growth cycles alternate between a growth phase (called anagen, it lasts about three years) and a resting phase (telogen, which lasts about three months). During telogen, the hair remains in the follicle until it is pushed out by the growth of a new hair in the anagen phase. At any one time, up to about 15 per cent of hairs are in telogen. But a

three months later, this large number of hairs will be shed. However, as the new hairs start to grow out, so the density of hair may thicken again.

Anagen Effluvium (Chemical Damage)
Like Telogen effluvium, this form of hair loss initially causes patchy loss of hair (which often then advances to total hair loss). In this form of hair loss, rather than just shutting down the hair follicle, a chemical actually

kills the hair follicle and anagen hair. The most common example of this are the effects of drugs used to treat cancer. Chemotherapy involves is a medicine that's injected into the body to kill cancer cells. In effect, it's really a poison that's designed to kill more bad cells (i.e., the tumor cells) than good cells. One of the side effects is the poisoning of the hair follicle, although hair usually grows back within six months of the end of chemotherapy.