Wrinkles are not due to genetics alone but also to stressful environmental factors, such as a divorce, abnormal weight loss and use of antidepressants, according to a study published Tuesday.

"A person's heritage may initially dictate how they age -- but if you introduce certain factors into your life, you will certainly age faster. Likewise, if you avoid those factors, you can slow down the hands of time," said study author Bahaman Guyuron, an American Society of Plastic Surgeons (ASPS) member.

Researchers examined 186 pairs of identical twins because "they are genetically programmed to age exactly the same," explained Guyuron, professor and chairman of the department of plastic surgery at the University Hospitals Case Medical Center, in Cleveland, Ohio.

The study found that twins who had been divorced looked nearly two years older than their identical siblings who were married, widowed or single. Researchers found that antidepressant use and weight gain were also factors in perceived age difference.

In sets of twins younger than 40, the heavier twin seemed older, while in sets of twins more than 40 years old, the heavier twin seemed younger.

"The presence of stress could be one of the common denominators in those twins who appeared older," said Guyuron.

Continued relaxation of the facial muscles due to antidepressant use could explain sagging, and losing abnormal amounts of weight has harmful effects on health and appearance, the researchers found.

The study was published in the web-based version of "Plastic and Reconstructive Surgery," the ASPS medical journal.

(Agencies via China Daily February 4, 2009)