What is hair loss?

Causes and Symptoms

The major reason that hair on the scalp thrives more lavishly than on other parts of the body is that scalp hairs are produced by the largest follicles found in human skin. Throughout the early years of infancy, these follicles increase in size, shedding their hairs about every two to six years to clear a path for a new hair that grows thicker and longer than the one that it replaced. In the mid-teens, nearly every follicle in an individual’s scalp is generating an actively growing hair, and by the late teens scalp hair reaches its adult size, populating the scalp in numbers that will never again be equaled.

For most adults entering their twenties, this situation reverses, and hair loss begins to occur—either permanently or temporarily. At this stage in their development, nearly every man and more than 80 percent of women find their hairlines receding. As the years progress, the shedding continues, and the density of scalp hair continues to diminish. Nearly all the permanent hair loss that affects the human scalp is produced by the natural aging process and/or common baldness.

The term “baldness” is often used when a definite hairline recession, a bald spot on the crown, thinning over the top of the scalp, or a combination of the three is detected. The sides and rear scalp fringe areas are usually spared, except for the inevitable thinning that accompanies age. These regions appear to be capable of generating enough two-to-six-year hair cycles to keep them well covered for most, if not all, of a male’s average life span.

The less frequent causes of permanent hair loss can be categorized into three groups. The first involves injury to follicles created by constant tension or pulling of scalp hair. Tight ponytails or chignons, worn over a number of years, often result in permanent bald patches on the sides of the head. In addition, tight rollers and the process of hair weaving kill follicles. The second infrequent cause of permanent hair loss is physical injury, such as a laceration or burn. If hair is ironed as a method of straightening over a period of years, hair follicles will become damaged. The third cause involves various inflammatory skin disorders and growths that occasionally affect the scalp. For example, a scalp wen, or cyst, tends to occur in families and requires no treatment unless it appears to be growing. Removal involves a simple office procedure and eliminates the bald spot that results from pressure of the enlarging cyst upon adjacent scalp follicles.

Nearly all humans lose some scalp hair every day. The number of falling hairs, however, often varies considerably from day to day. This daily variation in hair loss is not an indication of abnormality. An average of thirty to sixty hairs may be shed from the scalp each day. While days, weeks, and months may pass with little to no hair loss, large numbers of hairs may be lost over similar time periods. The yearly average, however, remains fairly constant.

This daily variation in hair loss merely reflects the fact that hair follicles act independently of one another. Their three-year growth and three-month rest cycles occur randomly. Aside from the tendency to lose more hair in the autumn, chance dictates the periods when the scalp will contain more resting hairs (hairs having small whitish roots).

Dandruff and its two related conditions of seborrhea and psoriasis, both scaly scalp conditions, may create a significant diffuse hair loss. Because these conditions are so common, they account for most of the shedding that requires medical treatment. In most cases, these problems can be controlled without medical assistance.

Temporary hair loss can result from alopecia areata, pregnancy, severe illness, surgery, certain medications, hormonal disorders, or dieting. Alopecia areata is a condition that usually produces temporary shedding of scalp hair, and occasionally body hair. In most cases, the hair regrows spontaneously or after medical therapy has ended. Occasionally, if this problem begins during childhood, all the scalp and body hair may be lost permanently. Extensive shedding may follow pregnancy or the discontinuation of birth control pills. After several months, however, the hair usually begins to regrow. Hair loss may also result from a severe illness associated with high fever (usually influenza) or an extensive surgical procedure. In the case of surgery, the cause is related to changes in body chemistry. Various medications can also create hair loss. The main offenders are the amphetamines, blood thinners, antithyroid drugs, anticancer drugs (as well as radiation treatments), and birth control pills. Hormonal disorders, particularly thyroid dysfunction, can create a thinning problem, but this condition is rarely an isolated symptom. In rare instances, improper nutrition can result in hair loss, such as in the case of dieters who eliminate protein from their daily food intake.

The conditions responsible for temporary shedding usually create a thinning problem quite rapidly. Aside from hair breakage or forcible extraction (hair pulling), the problem is usually one of increased numbers of resting hairs, resulting in massive hair loss. (The two conditions primarily responsible for creating permanent hair loss—aging and common baldness—usually develop slowly, over many years. Thinning occurs simply because the scalp follicles are no longer capable of producing new hairs.)

If something occurs to double the number of resting hairs from their normal 15 to 30 percent, then hundreds of hairs may fall each day. If this lasts for several months, about one-third of the scalp’s hair may be lost. A loss of about 30 to 40 percent is required before thinning becomes obvious. After the shedding abates, it may take years for the scalp hair to return to its original density, since the new hairs can grow only about an inch every two months.

Treatment and Therapy

Scientific research in the area of hair loss has produced a drug that has been relatively effective in some individuals. The drug minoxidil was originally used as an antihypertensive medication; however, 70 percent of patients taking it reported unexpected hair growth, occasionally in such undesirable places as the forehead. A 0.2 percent minoxidil solution for external use was devised by a major drug company in the United States and marketed under the name Rogaine. The Food and Drug Administration (FDA) approved Rogaine as the first prescription drug to effectively combat baldness.

Although it is uncertain how the drug works, it is believed that minoxidil enables shrunken follicles to grow back to a size capable of producing sturdy, visible hairs. Minoxidil has been shown to have promising, though limited, results. It is best at filling in those patchy gaps that herald the beginnings of baldness. Between one-third and one-half of men in some studies exhibited “significant” or “cosmetically acceptable” hair growth. Minoxidil is not a cure, however, and it requires a lifetime commitment. When the drug is stopped, hair thins out within months.

Much of the problem with all these chemical inducements aimed at hair regrowth or retarding hair loss is the lack of long-term studies to substantiate short-term treatments. For example, many patients who have tried minoxidil and other chemical stimulants and reported successful regrowth of hair have not continued applications over long enough periods of time to justify some of the claims made for these hair regrowth drugs.

Finasteride is an FDA-approved drug that is marketed under the brand name Propecia and taken orally. Propecia works by inhibiting production of dihydrotestosterone (DHT), an adrogen hormone that, among other things, shuts down growth of hair follicles. Without certain levels of DHT in the bloodstream, hair follicles continue to grow. Propecia has a reported 29 to 68 percent success rate but is effective only as long as it is taken; all hair gain is lost within six to twelve months if treatment is stopped. Propecia is most effective in promoting hair growth in the crown area of the scalp, which explains its popularity. Finasteride is ineffective for treating hair loss in women and may be harmful to pregnant women. Conversely, the drug works well for women who suffer from follicular sensitivity to androgens and may be prescribed by a physician who ensures that the patient is taking proper birth control measures while the drug is in use.

A third drug that is FDA approved for hair growth is Latisse, which is specifically used for eyelash growth. The active ingredient of Latisse, bimatoprost, is also found in Lumigan, a glaucoma drug. It is not known whether bimatoprost promotes hair growth in other areas of the body.

Another ointment that has gained popularity of use is Revivogen, although this drug has not yet been approved by the FDA. Ingredients in Revivogen consist mostly of a mixture of fatty acids that are derived from the de-estering of natural oils such as linseed oil and oil from seeds of borage plants. As with minoxidil, the mode of action is not completely known, but scientists suspect that Revivogen inhibits DHT levels in the scalp to combat hair loss.

Antiandrogen is applied as a topical medication to block the binding of DHT with hair follicles. Follicles that remain unblocked continue to grow hair. Antiandrogen occurs in Nizoral shampoo and Neutrogena T-Gel, which are readily available. Use of shampoos containing antiandrogen has so far produced mixed results. Some individuals report decreased hair loss rate but no hair regrowth in bald areas. In other individuals, the use of antiandrogens has produced no discernable reduction in loss of hair or hair regrowth in bald areas.

Ketoconazole, the active ingredient of Nizarol shampoo, is a synthetic antifungal drug used to prevent and treat fungal infections of the skin and mouth. Since it is both an antifungal and a 5-alpha reductase inhibitor, it can help to slow the balding process. There is some suggestion that ketoconazole could inhibit testosterone synthesis during embryonic development, which may inhibit genital development of the male fetus.

An herbal extract from the partially dried fruit of the dwarf palm called palmetto has been shown to be a DHT inhibitor producing few or no notable side effects. It is more commonly used to treat symptoms of prostate disorders. Topical applications of saw palmetto herbal extract have produced noted hair growth in six of ten subjects, but the other four test subjects reported no improvement. If further tests are successful, then the use of saw palmetto as a hair restorer may increase dramatically, as it is less expensive and has minor side effects compared to other hair restoration drugs.

Hair follicles contain stem cells that may be employed in hair restoration within a few years, pending the outcome of current studies and funding for programs to support those studies. This treatment method is variously labeled “hair multiplication” or “hair cloning.” Several companies are involved in the production of hair multiplication treatments based on follicle stem cells.

Another nonsurgical method for achieving permanent hair is hair weaving, a process that originated in the African American culture in the nineteenth century. Weaving hair involves braiding it tightly so that a toupee or smaller weft (section of hair) can be attached permanently. All that is required is a sufficient amount of hair remaining on the scalp to serve as an anchor for a hairpiece.

The braids are usually formed from the thicker hair found on the sides and back of the scalp. A semicircular ridge is created that holds a hairpiece firmly in place. If enough hair is still growing on top of the scalp, it can be twisted into smaller braids to anchor individual wefts. This type of weave permits better aeration and easier cleansing of the scalp.

A hair “fusion,” “bonding,” or “linking” is like a weave except that the hairpiece or wefts are glued, instead of tied, onto the braided hair. This so-called chemical bond is insoluble in water and quite caustic. Frequent hair breakage has limited the usefulness of this method.

While weaved or fused hair does not grow, it still requires regular care and maintenance to keep it looking acceptable. The scalp hair used to anchor the weave naturally continues to grow. As it grows, the attached hair starts to ride above the scalp. Thus the weave or fusion must be reanchored frequently (as often as every three weeks). In addition, the tension placed on the anchoring scalp hair creates accelerated shedding, and this hair loss is often irreversible.

Hair implants, also known as medical or suture implants, have become the principal method for fixing a hairpiece securely to the scalp. Implants are usually not permanent, are only quasi medical, and are to be distinguished from transplants, with which they share a resemblance in name only. Implants are stitches made from either stainless steel or nylon-type materials that are sewn into the scalp and tied into rings. Like the weave hair braids, the knotted stitches act as anchors, holding a hairpiece or several wefts against the barren scalp. If the implants secure a hairpiece, only two or perhaps six stitches are needed. If the implants anchor many smaller wefts of hair, however, more than a dozen stitches must be sewn into the scalp. A physician must perform this procedure, since only someone with a medical license can inject a local anesthetic and sew stitches into the scalp. The problems generated by sewing and leaving stitches in the scalp, however, are pain, infection, and scarring.

In the 1970s, a surgical procedure known as tunnel grafting was developed. This procedure is not available in implant clinics. A small rectangle of skin is removed from behind each ear. The two pieces are immediately grafted to the front and back of the scalp to form two loops that serve as anchors for a hairpiece. While the operation is relatively simple to perform, extreme care must be taken to ensure proper graft acceptance and healing. Although this method avoids the pitfalls of implanted stitches, it still retains two of the problems common to any kind of artificial anchoring device. Since only two loops are available to fix a hairpiece, the hairpiece can still lift off the scalp. In addition, the skin loops are as vulnerable to injury as suture loops. Scalp lacerations resulting from forcible removal of the hairpiece have occurred.

The hair transplant procedure was developed in the 1960s to late 1970s. It is estimated that in the United States alone nearly twenty thousand men and women undergo hair transplant surgery each year. As with the implant procedure, a practitioner must have a medical license to inject a local anesthetic into a person’s scalp and make the surgical incisions required for a hair transplant. Doctors who specialize in hair transplants are usually dermatologists; some are plastic surgeons.

Even the baldest scalp contains thousands of transplantable hair follicles. To move them where they are most needed, three surgical methods have been developed, employing scalp grafts known variously as “flaps,” “strips,” and “plugs.” While all three methods are used, most hair transplants are performed with plug grafts because they are the simplest and safest to work with and yield the most satisfying results. The transplant candidate need only be bald enough to justify undergoing the procedure and be endowed with enough side and rear fringe scalp hair to make the procedure worthwhile.

To create a flap or “full thickness” graft, a surgeon cuts out three sides of a rectangular patch of scalp from above the ears and swings it over to the bald area to create a new hairline. This is a major hospital procedure requiring considerable surgical expertise. Although a fairly large portion of bald scalp can be provided with instant hair density, this method is fraught with problems. To ensure a proper take, or graft survival, the blood vessels feeding the transplant must remain intact while they are moved along with it. Because the vessels are quite fragile, they are frequently damaged, resulting in poor graft survival and catastrophic hair loss.

To alleviate this problem, a variation of this type of transplant, known as a free flap procedure, was developed by a team of Japanese surgeons. The free flap is cut out on all four sides, completely severing the blood supply. After setting the graft into its new location, the surgeons meticulously reestablish its blood supply to the recipient blood vessels using a delicate microsurgical technique.

Even if this technical obstacle is surmounted, however, other aesthetic problems remain. The first problem involves the surgical scar that delineates the border between the forehead and the transplanted hairline. Little can be done to minimize this scar. The other problem concerns the unnatural direction in which the newly transplanted hair grows. A flap graft cannot provide hair that will grow in the direction of the hair that has been lost. Hairs growing from the sides of the scalp exit much closer to the surface than in other areas. When transplanted to the frontal area, these hairs lie flat against the scalp. Thus, while a flap may provide a faster way to achieve a high-density transplant, the problems of graft survival and poor aesthetic results have limited its usefulness.

A surgical strip graft is a narrow rectangular patch of scalp, cut out on all four sides, that is usually transplanted to create a hairline. Unlike the larger flap, its blood supply need not be moved along with it or be laboriously reestablished. After the strip is placed into its new location, the adjacent bald scalp sends new blood vessels directly into it. Like a flap graft, however, it must be sewn into place. If it is used to create a hairline, a scar will mark its border with the forehead as well. While this procedure can be performed in an office rather than at a hospital, extreme care must be taken to avoid damaging this delicate graft. Despite the most painstaking precautions, poor takes result quite often. Areas of nongrowth are common, and not infrequently the entire graft becomes almost completely devoid of hair.

A “hair transplant” usually refers to a procedure in which a small cylinder of hair-bearing scalp, or plug, is taken from the rear or side fringe areas and transferred to either the bald crown or the scalp’s frontal region. While this transplant method requires several sessions to approach the density of hair acquired with a flap graft, the ease with which it can be performed, coupled with its superior aesthetic results, make it the logical choice for surgically replacing hair.

The surgeon uses a trephine, or “punch,” to remove the cylindrical section of scalp, properly called a donor graft rather than a plug. The graft is quite small, measuring about 0.8 centimeter deep by 0.5 centimeter in diameter. The hair follicle is intimately related to all three skin layers. The bulb—or hair-producing portion of the follicle—lies within and is cushioned by the fat, or adipose, layer. The entire follicle is supported by and receives its nourishment from the fibrous portion of skin, or dermis, which is about 0.6 centimeter thick in the scalp. The skin mantle, or epidermis, provides the opening, or “pore,” through which the hair exits to the surface of the scalp.

When a donor graft is removed, all three skin layers must be included. The hair is actually superfluous to the procedure: The hair follicle is all that is essential. After removing the hair-bearing donor grafts, the physician next punches out identical sections of bald scalp. The term “plug” actually refers to the hairless cylinder of scalp that is taken from the bald area. The donor graft is placed into the void left by the removal of the bald plug. Light pressure is applied for several seconds to allow the blood to clot and hold the graft in place. Because these grafts are so small and clotting occurs so rapidly, stitches are not required to fix them in place.

Within hours, new blood vessels move into the graft from the surrounding skin to feed the new section. Within several days, as healing continues, the graft and its adjacent host skin become one. Keeping the grafts small facilitates easy penetration by these vital blood vessels. When larger grafts, or strips, are used, the blood supply may not reach all the hair follicles, and they die.

Because of the small size, the grafts’ rounded edges blend into the host skin quite evenly, creating an acceptable hairline. While they might appear obvious on close inspection, they are always less noticeable than the borders left by flaps and strips. Because the grafts are small and are taken from the rear half of the scalp, where the hairs grow out in the same manner as the front and crown hairs, they can be directed to duplicate exactly the original pattern of growth in the bald host areas. This method is a minor office procedure that, in the hands of an experienced physician, is considered safe, with little discomfort experienced by the patient.

Perspective and Prospects

The observation that eunuchs are not subject to gout or baldness was made by Hippocrates in the year 400 BCE and is contained in the Hippocratic Corpus as a short medical truth or aphorism. Aristotle, himself balding, was interested in the fact that eunuchs did not become bald and were unable to grow hair on their chests. These observations were either forgotten or overlooked for the next twenty-five centuries, and medical science remained baffled by male pattern baldness until James B. Hamilton, an anatomist, in 1949 again made the observation that eunuchs did not become bald. His suggestion that androgens are a prerequisite and incitant in male pattern baldness and his later classification of the patterns and grades of baldness are landmarks in the study of male pattern baldness. Subsequent investigations of hair loss confirmed the significance of androgens in male pattern baldness, and Hamilton’s classification remains in use.

Hamilton demonstrated conclusively that the extent and development of male pattern baldness were dependent on the interaction of three factors: androgens, genetic predisposition, and age. In summary, he found that genetic, endocrine, and aging factors are interdependent. No matter how strong the inherited predisposition, male pattern alopecia will not result if androgens are missing. Neither are the androgens able to induce baldness in individuals not genetically predisposed to baldness. The action of aging is demonstrated by the immediate loss of hair upon exposure to androgens in the sixth decade of life, whereas hair in young men exposed to androgens tends to remain much longer.

Over the centuries, men have tried every imaginable approach to retain hair. They have shampooed their scalps with tar, petroleum, goose dung, and cow urine. They have stuck their heads into rubber caps connected to vacuum pumps to suck recalcitrant hairs to the surface. In the 1960s, hair transplants became the most efficient and aesthetically pleasing method of retaining scalp hair. Research in the area of drug treatment continues.

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