Dr. Eric Finzi of the Chevy chase Cosmetic Center conducted the pilot trial to test whether preventing a patient from frowning would make it difficult to feel sadness.

Rainy days used to bring Kathleen Delano down. She's suffered depression since her 20s. Antidepressants and therapy didn't help.

"I wasn't suicidal, but I wasn't interested in getting out of bed. I wasn't interested in talking or communicating with friends or family," she said.

Then she enrolled in a study testing the effects of botox on depression. Dr. Eric Finzi of the Chevy chase Cosmetic Center conducted the pilot trial to test whether preventing a patient from frowning would make it difficult to feel sadness.

"To feel emotions, you have to express it on the face," he said.

The study involved 10 patients who were clinically depressed.

Dr. Finzi injected a normal dose of botox into their brows. Two months later, nine out of 10 patients were no longer clinically depressed.

"You're basically preventing people from expressing those sad and angry emotions on their face. Somehow, that's feeding back directly to the brain," said Dr. Finzi.

Results are gradual and take a week or two to kick in.

"It's not like you take the botox and 'Hallelujah, I'm healed,'" said Dr. Finzi.

Dr. Finzi said this initial data is promising. But he believes a larger study is still needed.

Kathleen is already a believer.

"Really feeling for the first time in a lot of years that I'm free of depression," she said.

When the botox wears off, so does the antidepressant effect, so patients would need to get the shots about every three months.

A single botox treatment costs about $400.