For years, your dermatologist has been telling you to use sunscreen regularly to prevent aging. But the funny thing is, if you're like most people, you've opted for sexier, more expensive and less effective creams and potions.

Recently, doctors in Australia designed a study to motivate sunscreen use. The Wall Street Journal, June 3rd, describes a study in the Annals of Internal Medicine, demonstrating that people instructed to apply sunscreen every day showed 24 percent less skin aging, as measured by lines and coarseness of the skin, than those told to use the cream as they usually do.

Though we have known for a long time that sunscreen might prevent skin aging, this study provides the first hard evidence. The designers of the study had a hidden agenda: through an appeal to vanity, their goal was to prevent skin cancer. Large, randomized trials have not been done before simply because they're difficult to arrange and expensive.

The study, funded by the Australian government in an anti-cancer initiative, included 903 adults under 55, living in Nambour, Australia, which is near the country's Sunshine Coast. Young participants were chosen so that results didn't reflect natural aging.

All participants were given sunscreen with a sun protection factor (SPF) of 15+. Half were instructed to apply the sunscreen daily to exposed areas, reapplying after water immersion, heavy sweating or several hours spent outdoors, while half were told to use it as they normally would.

By the end of the study 77 percent of those told to use sunscreen daily were using it at least three to four days a week, compared with 33 percent of the control group.

Researchers took silicone impressions of the backs of participants' hands at the beginning of the study and after 4.5 years. Evaluators then graded the patterns of lines and skin coarseness on the hand impressions on a scale of one to six. The damage seen on the surface of the skin reflects tissue damage underneath the skin. They found reduced skin damage from UV rays, which also translates to a lower risk of skin cancer.

Protect yourself
• If you're young, your sunburn may put you at risk for skin cancer decades later.
• Buy a broad-spectrum sunscreen, protecting against both UVA and UVB ray that has an SPF of 30 or higher to reduce the risk of early skin aging and skin cancer. 
• Products claiming water resistance must say how long you can expect to get that protection while swimming or sweating, either 40 minutes or 80 minutes.
• Sunscreens can no longer be called "sunblocks" or be labeled as "waterproof" or "sweatproof."
• Finally, slather sunscreen on heavily.
If you already have sun damage, consult with a board-certified plastic surgeon for remedies and start using sunscreen religiously.