The hypothesis is as follows: An injection of Botox (off label usage) blocks the release of a chemical called acetylcholine which then inhibits contraction of a facial muscle and prevents frowns (or wrinkles). A new discovery about what causes depression has to do with acetylcholine; this neurotransmitter, which can be blocked by Botox, accumulates in the nerve and thus tells the brain to make some chemical changes thus working as an antidepressant. Botox could possibly hold the solution to treating depression and it has nothing to do with erasing fine lines and wrinkles. Botox is believed to rebalance brain chemistry so that an antidepressant response occurs.
Research has found that after a single round of Botox injections 52 to 90% of patients who suffered from depression reported elevated moods!
What is interesting is that the antidepressant effects from Botox continues weeks after wrinkles reappear and the Botox wears off. This finding supports the scientific belief that Botox may go beyond just a cosmetic improvement.