Cosmetics counters are full of anti-aging medicines, but only a few have been shown to work.

By NICHOLAS BAKALAR

Remedies that promise to smooth wrinkled skin are a common offering of frauds everywhere, but now there is strong evidence that certain kinds of treatment are effective.
The key is a growing understanding of the skin’s connective tissue, called the dermal collagen .
A recent review in The Archives of Dermatology concludes that three anti-aging treatments are proven clinically effective: the topical application of retinol; carbon dioxide laser resurfacing; and injection of hyaluronic acid, a moistureretaining acid that occurs naturally in the skin. Each depends on the interaction of skin cells called fibroblasts with the collagen they produce.
“This is an area where there’s a lot of hype and not much substance,” said David J. Leffell, a professor of dermatology at Yale University who was not involved in the review. But, he said, this study is “good science.”
Theory and experiment back these treatments, the authors write. Fibroblasts - connective tissue cells - secrete a complex group of polysaccharides and proteins that creates collagen, which gives the skin shape and elasticity and supports the blood vessels that permeate it. The network of collagen tissue is maintained by its tension with these skin cells.
Skin deteriorates as it ages, but its exposure to sunlight inhibits the ability of fibroblasts to produce collagen. The hands, face, neck and upper chest all suffer more than unexposed skin, and lightpigmented people wrinkle more readily than others.
But there are treatments that counter this process. Topical application of retinol, a form of vitamin A, was the first to be proved useful. Although the molecular pathways are not well understood, retinol causes new collagen to form in aged skin and in skin damaged by ultraviolet light.
Skin creams with retinol are available over the counter, but many do not indicate the concentration of the active ingredient. “Many products just refer to retinol or vitamin A as a buzzword,” said Gary J. Fisher, the lead author of the review and a professor of dermatology at the University of Michigan.
Concentrations of 0.2 to 0.6 percent are enough, Dr. Fisher said .
Carbon dioxide laser resurfacing is another well-tested treatment for wrinkles. The laser removes thin layers of skin without damaging surrounding tissue. As the wound heals, new collagen is produced.
The third effective treatment is injecting a form of hyaluronic acid, similar to a substance the skin normally produces, into the dermis that underlies the wrinkles. This was originally designed as a space filler, with no intended physiological effect. But as the injection stretches the dermis, the fibroblasts respond by producing more collagen .
Do the benefits of these treatments outweigh the risks?
“It’s a matter of the kind of problem a person perceives and how he wants to deal with it,” Dr. Fisher said. “For these treatments, which have sound research behind them, and for people who want to improve their appearance, the benefits far outweigh any problems.”