Alopecia

Hair loss can be a physiological consequence of advancing age, but it can also depend, for example, on stress.

What is it

The term alopecia describes a symptom and not a particular disease. In itself it indicates the loss and non-regrowth of hair (or hair) in an area where they are normally present.

Hair has a life cycle consisting of three phases, regulated by the activity of the hair follicle (the structure contained in the thickness of the skin from which the cells that determine the growth of the hair originate):

	Description	Duration
Anagen	Period of proliferation of follicle cells	2-7 years (the duration is influenced by hormonal factors and hereditary factors and usually longer in women than in men);
Catagen	Period of gradual arrest of follicular activity	2-3 weeks
Telogen	Period of absolute rest of the follicle before hair loss	2-3 weeks

After the hair falls, at the end of the telogen phase, the empty follicle is reactivated, starting a new anagen phase to generate another.

In humans, unlike what happens in other mammals in which the renewal of a large part of the hair coat periodically occurs, this cyclic evolution is not synchronous, so each hair grows independently of the others: as far as hair is concerned, under normal conditions 80-90% of the total is in the anagen phase, about 1% in the catagen phase and 10-20% in the telogen phase.

Any factor that interferes with the sequence of these phases and especially with the proliferative activity of the follicles can alter the physiological balance between hair loss and regrowth.

Causes

To determine an imbalance between hair loss and growth can be different factors: the physiological involution of hair follicles of old age, the effect of male sex hormones, a genetic predisposition, conditions of physical or mental stress, inflammatory alterations of the scalp skin, some systemic diseases, the effect of some drugs, nutritional deficiencies, exposure to toxic substances, mechanical factors.

The most frequent clinical forms are:

• androgenetic alopecia, which is characterized by the shortening of the anagen phase of most of the follicles of the affected areas, with the production of hair that does not grow and passes rapidly into the telogen phase; depends on an increased effect of male hormones at the follicular level mediated by a genetic predisposition
• telogen effluvium, which is characterized by a rapid increase in the proportion of hair in the telogen phase, and therefore by a much higher than normal loss; is related to physical or psychological stress or pregnancy/childbirth (in acute form), thyroid dysfunction, nutritional deficiencies (in chronic form)
• anagen effluvium, which is characterized by a drastic reduction in the proliferative activity of the follicles, and therefore by a lack of regrowth; can be caused by chemotherapy, radiation therapy, exposure to toxic substances
• Alopecia areata, which is characterized by a dysfunction of the follicles dependent on a localized inflammatory process, and is often of autoimmune origin.

Symptoms

In androgenetic alopecia, also called common baldness, the clinical presentation is somewhat different in the two sexes.

In men, who are affected much more frequently, the areas initially affected are usually the fronto-temporal ones (with the formation of the classic “receding hairline”) and the vertex, but the thinning patterns can also vary from subject to subject, the onset is almost always early (around 30 years) and the progression more rapid.

In women, who are affected to a lesser extent and often in conjunction with conditions of hormonal imbalance that involve a decrease in the activity of estrogens in favor of that of androgen hormones (pregnancy, menopause, polycystic ovary, taking oral contraceptives), thinning tends to be localized in the central areas of the head (vertex, forehead), occurs more slowly and progresses more gradually.

Often, but not a rule, androgenetic alopecia is accompanied by an increase in sebaceous secretion (seborrhea) and a fine peeling of the skin (dandruff).

In the forms of effluvium, in which the most striking event is the increase in the number of hairs that fall out daily, thinning can affect any area of the head and is usually widespread, it occurs gradually or suddenly and progresses acutely or chronically depending on the cause (stressful event, systemic disease, drugs, toxic substances, etc.).

In the forms of anagen effluvium, hair loss is generally much faster and, in the absence of regrowth, complete hair loss can occur.

Alopecia areata typically presents with sudden hair loss in small, well-defined patches of roundish shape that can be distributed anywhere, but more often localized in the temporal and occipital regions, that is, on the sides and nape.

This form can affect both sexes and all age groups, although it is rare after the age of 60. The progression with involvement of most or all of the scalp is a sporadic occurrence, unfortunately more frequent when the disease begins before puberty.

Forms of alopecia are amenable to healing, with hair regrowth in the affected areas, depending on the cause and triggering event.

Only in male androgenetic alopecia linked to constitutional factors the process of involution of hair follicles, which leads to the gradual reduction of the hair, is irreversible, although it can be partly counteracted with some drugs. In other forms, however, removal of the cause (stress, medications, toxic exposures, etc.) or control of the underlying disease allow temporarily dysfunctional follicles to resume proliferative activity.

Diagnosis

The evaluation of a form of alopecia involves first of all a dermatological examination and the execution of specific trichological examinations, which allow to evaluate in a hair sample the prevailing evolutionary stage and any structural alterations of the stems and hair bulbs.

Subsequently, depending on which is assumed to be the cause of alopecia, some targeted laboratory tests may be necessary (hormonal dosages, dosages of vitamins and minerals, hematological tests, protidogram, inflammatory indices, immunological tests, etc.).

Treatment

The treatment of alopecia obviously starts from the treatment or correction of the causes when these are identifiable in a disease, an inflammatory process, a hormonal imbalance, a drug therapy, a deficiency of nutrients, etc.

In male androgenetic alopecia it is possible to intervene, as long as it is at an early or intermediate stage, slowing down hair loss with some drugs: minoxidil, used in local administration, which has a stimulating effect on the hair follicle, or finasteride (and similar molecules) to be taken by mouth, which blocks the excessive production of testosterone metabolites at the follicle level.

In female androgenetic alopecia, preparations based on progestogens or estrogens for topical use may also be recommended.

The treatment of alopecia areata involves the use of drugs that counteract the immune process that determines it, such as corticosteroids, in local application or, if necessary, systemically.

A series of preparations based on plant extracts with various effects (stimulant on the microcirculation, astringent, sebum-regulating, antiseptic, anti-inflammatory) can be useful as adjuvants for local use.

Some other drugs and plant derivatives with antiandrogenic effect already in use with other indications are being studied, such as azelaic acid (used in the treatment of acne) or Serenoa repens extract (used in the treatment of prostatic hypertrophy), and also the association of zinc and vitamin B6.