With at least forty treatments for baldness patented in 1996 and $200 million budgeted for clinical trials in 1997, you'd think someone might have figured out by now why men lose hair. But the lab guys know only one big thing: Hair follicles shrink and die. They've proved that this tragedy is triggered by the body's especially potent testosterone derivative, DHT. But researchers can still only theorize about why the perfectly normal presence of DHT leaves some otherwise healthy men mourning their hair as it swirls down the drain.

According to Houston researcher Dr. Peter Proctor DHT fouls up the "grow hair" and "shed hair" mechanisms in follicle cells. The good guys, Proctor postulates, are nitric oxide (NO) molecules that are secreted from nearby blood-vessel walls. They trip the cellular "grow hair" switch. The villain is superoxide--a highly reactive chemical produced by immune cells that accumulates around hair follicles. Superoxide throws the "shed" switch.

Even healthy follicles release their hair about every four years, but balding men shed more often. Their follicles, when DHT attaches to them, may excrete a protein that is not recognized by the body. The immune system then sends in the cavalry, triggering the release of more superoxide. "It's like when a transplanted organ is rejected," says Proctor. It's bad enough that superoxide throws every shed switch in sight, but it seems to react with nitric oxide to form toxic chemicals that irritate the follicles the way a strong bleach burns the skin.

Under this onslaught, a balding man's follicles shrink and sicken until the growth cycle is reduced from four years to a pathetic four months. To add to the outrage, their shrunken size makes for fine and uncolored hair, baby fluff that can never camouflage a shiny pate.

According to Dr. Ken Washenik, director of dermatopharmacology at NYU Medical Center, such a process may not be reversible. "I am much more optimistic," he says, "that we can stop hair loss before it happens." The moral is that hair-loss treatment should begin before bare skin appears. Men seeking to hold their hairline are now turning to three main drugs.

MINOXIDIL

The now-ubiquitous minoxidil was first approved in 1979 as a blood-pressure medication. Unfortunately for women, who preferred their faces hairless, it made some people sprout hair everywhere. When topical application showed localized hair growth, the drug was rolled back into the lab and rolled out ten years later as Rogaine. Absorbed through the skin, minoxidil probably mimics NO, throwing the follicles' grow switches. In trials, it promoted moderate regrowth on only 39 percent of the men who used it for a year. But because it remains the only FDA-approved hair-loss drug, it's the bazooka in the balding man's battery. Practitioners like Washenik say it's the best bet for slowing the loss of existing hair.

PROPECIA

The next treatment to grind its way through the FDA-approval machinery, probably within the year, will be Merck's promising finasteride tablet, Propecia. Finasteride inhibits the enzyme that turns testosterone into DHT--the first domino in the chain reaction that ends in follicle death. It first appeared in the guise of Proscar, a drug that combats prostate enlargement, another problem caused by DHT. Merck's trial results have raised high hopes for Propecia's effectiveness: More than half of those treated had "clinically significant increases in growth of new hair." Some baldsters, wanting to get the jump on the approval process, are already cadging prescriptions for Proscar from their physicians.

TRICOMIN

Developed at ProCyte in Kirkland, Washington, Tricomin is expected to come out in the next year, too, not as a drug but as an additive in shampoos and conditioners. Early trials of a Tricomin topical solution resulted in 40 percent denser hair growth in 80 percent of participants, but its approval by the FDA could be years away. The copper-peptide compound may neutralize the superoxide that makes follicles shed. Meanwhile, some balding men already slather on another of ProCyte's copper-peptide compounds, Iamin, an over-the-counter gel originally developed to help heal wounds.

As these new drugs head toward FDA approval, experience has already shown that they often work best in combination, each combating a different facet of the balding process. While finasteride, for example, prevents further DHT damage to follicles, minoxidil coaxes those already weakened into growing good hair again. Thus, some practitioners prescribe minoxidil and Proscar together. Other physicians tout proprietary mixtures. Proctor's laboratory produces Proxiphen, a prescription of compounds that mimic the NO grow message, neutralize superoxide, and prevent DHT formation. In New York, Dr. Adam Lewenberg supplies a prescription hair-spray combining minoxidil with the antiaging skin treatment Retin-A, which seems to assist absorption. He claims that his combination grows new hair in go percent of patients.

Before you pester your doctor for prescriptions, however, beware the risks of using drugs "off-label"-- for purposes other than those they were approved for. Proscar, for example, was developed for use in older men; its long-term safety in younger men has not been established. So for now, you might want to stick to Rogaine.

Or you could join the likes of Michael Jordan and Patrick Stewart and be cool with your heritage.