THE DERMATOLOGIST LOOKS AT THE HAIR PROBLEM* By EUGENE F. TRAUB, M.D. New York, N.Y. S•½cE EV•R¾O• has hair, either too much or too little, daily attention must be giyen to this appendage either by combing, brushing, shaving, washing, cut- ting, or arranging. Innumerable preparations are sold to aid these processes and to help eliminate un- wanted hair or to stimulate and grow new hair. The therapeutic claims used to promote the sale of these items are such that it is well to study, for a moment, the basic knowledge we have concerning hair. At once one becomes aware that most of our information is based on legend or theory rather than on act- ual proved facts. Even the phylog- eny of the hair isnot entirely settled. For those who have not been in- clined to postulate a primary sensory function for hair, i.e., its derivation from scale borne sense organs of reptiles or tactile spots of mam- malian skin, one of the simplest and at the same time most plausible views is that hair, feathers, and scales are morphologically equiva- lent. There are many develop- mental features that speak against * Presented at the May 13, 1947, Meeting, New York City. such relationships. There are some resemblances between hair and teeth and those who would homologize the two structures point out that certain developmental disturbances in the pilary system are associated with malformations in tooth de- velopment. Danforth (1) concludes that for the present, we must con- tent ourselves with regarding mam- malian hair as akin to lateral line organs, tactile organs of' reptiles, placoJdal scales, teeth, claws, der- mal scales, and feathers. It is more closely related to some of these structures than to others, but with none of them is it fully homologous. The subject offers an attractive field for future research. The actual process of hair ex- change, commonly called shedding of the hair, continues throughout life. Shedding of the hair in humans differs from that in animals in that it is a constant phenomenon although it may progress more rapidly at cer- tain seasons than at others. The hair loosens from its papilla and rises up to the level of the middle of the follicle. It here becomes at- tached to the hair bed and is called a bed hair to differ it from the 129

130 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS papillary hair. Simultaneously, the walls of the lower third ot the follicle collapse on each other and the papilla shrinks while the lower end of the separated hair widens out and becomes broom-like. The hair continues to grow while attached to the hair bed and finally its in- creased size pushes it farther and 'farther up the follicle until it reaches a point just below the opening of the duct of the sebaceous gland. At this point, it is no longer nourished by a vascular supply so it stops growing, separates itself and falls out. According to Unna (2) the blood supply of the follicle con- trols nicely the growth and subse- quent shedding of the hair. In normal scalps after an interval, the papilla starts to regenerate and a new hair gradually rises in the follicle t6 push the old hair up ahead of it or less often it grows alongside of the bed hair. It is believed that the same papilla produces hair throughout life and that a new papilla is rarely produced after puberty. It is thought that this regeneration is caused by the supply of blood to the papilla and though we understand the mechanism of the a•ctual shedding, we have no idea what controls the blood supply of the papilla and follicle. Here we lack vital basic information that is of the utmost importance in the maintenance of good hair growth, If it is true that new papillae are rarely formed after puberty, the old ones must be preserved and kept healthy if we are to continue to grow hair. What do we know about growing hair and what factors influence the rate of hair growth? Surprisingly enough, we have practically no ac- curate basic knowledge on these fundamental points. Heredity is known to be of importance. How- ever. there is no sharp line of de- marcation between what is normal and what is abnormal, the same physical trait may have different meanings in two persons. For ex- ample, a full beard has a different significance to a white man than ' to an Indian• While it is recognized further that the tendency to premat- ure baldness appears to be familial and hereditary, no additional light as to why this occurs or how it is brought about is gained from that observation. Vascular and nervous factors are of basic importance. The regula- tion of the blood supply to the folli- cle is no doubt under control of the sympathetic nervous system and thi• in turn is intimately related with the central nervous system. The effect of emotional factors on hair loss and the graying of hair as seen in alopecia areata and achro- motrichia is, of course, well known. A striking example was reported by Barabal and Freeman (3) in the case of a 38-year-old white soldier, who, following a three-mile hike in De- cember, 1943, developed a sudden sharp pain in the left chest and fainted. Examination revealed no organic disease. During that night he was restless and tense and felt as though he were on the verge of a "nervous breakdown." The next