Emerging Model for Pattern Balding (after Kligman, others )
Balding begins when male sex hormones do "something " to the scalp hair follicle which causes it to be read as a "foreign body". Your immune system then mounts an attack on the hair folllicle. The main damage in pattern hair loss is probably immunologically-mediated. Damage to lining of blood vessels, which produces hair growth factors, makes the balding process worse.
Hormonal factors:
Castration, lack of DHT-receptors/enzymes (testicular feminization) , feminine status block the progression of balding and hair loss. However, women and castrated males have other sources of androgens and can still experience pattern loss.
Immunological factors:
Microscopically, balding looks like organ rejection. That is, increased number of immune system cells clustor round the base of the scalp hair follicle. Interestingly, lessor numbers of immune system cells normally cluster around the hair follicle. These may have a role in the normal hair cycle.
Organ rejection drugs ( e.g., cyclosporin ) reverse balding better than antiandrogens. This gives a rough indication of the relative importance of hormonal verses immunological factors in maintaining the balding state. Conversely, cyclosporin and similar agents may also have a "phenytoin-like" action on follicles which induces hair regrowth, separate from their immunosuppressive properties.
Antibodies to hair follicles are also present in blood in some cases of pattern hair loss.
Blood Vessel Lining in Pattern Hair Loss
Antiandrogens: E.g.: Propecia (Finasteride), Cyoctal, spironolactone.
These agents have significant hair regrowth properties.. They are also useful as adjuvants to other hair loss treatment where they 1) make it work better 2) Help prevent tolerance. Every few years, a new antiandrogen will be presented as the ultimate "solution for balding". This has yet to work out. E.g., clinical trials with cyoctal, arguably the most potent topical antiandrogen, were terminated because of lack of effectiveness. Even castration, the commonly used treatment for prostate cancer, generally doesn't do a lot for balding and hair loss.
Arguably, the most promising new antiandrogen is Propecia ( finasteride), from Merck. For more on this agent, go to propecia.com. Tho the weakest antiandrogen on paper, it seems to be as effective as the others in baldness treatment. My experience is that oral finasteride works about as well as topical spironolactone, about a 50% response rate, at one year. Some individuals take even longer to respond.
BTW, I have prime patents in this area ( for growth stimulators plus antiandrogens ). In fact, because of the publication of our patents, the combination of a hair growth stimulator plus and antiandrogen is now " obvious " and thus unpatentable. I sure wish antiandrogens worked better.
Possible explaination: Male hormones only initiate balding. Further, whatever hormones do seems to be mostly irreversible. The main damage to the hair follicle seems to be done by other factors, especially immunological. But I reserve the right to change my mind about this.
http://www.drproctor.com/baldfaq1.htm