Alopecia

Alopecia : from the Greek "alopex" = fox, a term used to emphasize the similarity with this animal, which loses hair twice in a year.

There are two main types of alopecia, the telogenic and the androgenic.

The first involves, usually in a short time, a limited or generalized fall of the hair, in response to a strong physical or psychological stress. This type of alopecia, which can affect both men and women, is reversible. Between the two, it therefore represents the "beneficial" form.

The other type of alopecia is called androgenic, to emphasize that it affects mainly, but not exclusively, men. In these cases, the term "losing hair" is not entirely correct, since the hair follicles, although undergoing a gradual process of involution, which leads the hair to lose its terminal appearance and to acquire the characteristic features of the fleece (hair very thin, soft and depigmented), they remain numerically the same. Contrary to what has been said for the telogenic form, androgenic alopecia is irreversible.

As we age, physiologically, the hair follicles on the forehead and temples undergo a gradual process of involution, with consequent thinning of the hair present in these areas. This phenomenon is valid for both men and women, where the problem, although less evident, is accentuated after the menopause.

Androgenic alopecia can clearly affect women of childbearing age, almost always due to important hormonal changes. In many cases, in fact, there is a higher level of typically male hormones, above all dihydrotestosterone.

The etiology of androgenic alopecia has not been clarified, although some things seem certain by now. It has been shown, for example, that the presence of androgens is necessary for it to manifest; for this reason a child will never suffer from androgenic alopecia. It has also been observed that in men predisposed to baldness the activity of 5-α-reductase is greater than normal. The same enzyme, which promotes the transformation of androstenedione into dihydrotestosterone, stimulates the secretion of the sebaceous glands. An excess of sebum (see greasy hair) tends to weigh down and subtract vitality from the hair, but does not directly atrophy the follicles. For this reason the term seborrheic alopecia has now fallen into disuse.

Numerous hypotheses have been put forward on the etiology of alopecia, see two.

Some speculate that in the follicles of subjects prone to baldness, there is an accumulation of a substance with inhibitory action, which accelerates the frequency of growth cycles. This substance would be produced during the anagen phase and would imply a rapid transition from the growth phase to the telogen phase. Because of this phenomenon, the size of the follicle would be reduced cycle after cycle, making the hair more and more fragile and thin.

A second hypothesis assumes that at the base of alopecia there is an inflammatory process at the level of the bulbs. In response to this phenomenon autoantibodies would form, which would block the activity of the matrix, that is, of that group of cells that, dividing, allows hair growth. The production of these autoantibodies would be genetically dictated.

the nails "