Botox may smooth your wrinkles, but it can dull your ability to understand the emotions of others, a new study suggests.

Botox, used in cosmetic and medical procedures for 20 years, paralyzes muscles, hindering certain facial movements, such as frowns, that over time can cause wrinkles.

Therein lies the problem, says David Neal, a psychology professor at the University of Southern California, lead author of the research, published today in the journal Social Psychology and PersonalityScience.

"People who use Botox are less able to read others' emotions," says Neal, who worked with a researcher at Duke University in Durham, N.C.