Botulinum toxin has actually been shown to improve depression!
Botulinum toxin was first isolated in the 20s, was first used therapeutically in 1968, and became approved in 1989 for eye issues. It has been used heavily for cosmetic use since 2002, and it was the first aesthetic drug ever approved. All that is to say...it has a lot of safety data behind it. Recent evidence (coming out this week) proves that botulinum toxin does NOT enter your brain as it's distant cousin tetanus toxin does, which is where that theory came from.
Botox, Dysport and Xeomin are the 3 botulinum toxins approved for cosmetic use in the US. They all work in the same way, at the presynaptic terminal blocking the release of acetylcholine - making the nerve temporarily unable to communicate with the muscle. It is broken down as a protein in our body with liver metabolism. Effects are temporary, and repeated use serves to take tension off of your skin, relaxing lines and wrinkles.
To ensure you are receiving the highest level of care, seek out a modernly trained, new-school dermatologic surgeon, oculoplastic surgeon, facial plastic surgeon or plastic surgeon who is board certified and fellowship trained in one of these "core four" cosmetic specialties. Membership in organizations like the American Academy of Facial Plastic and Reconstructive Surgery help to identify a highly trained surgeon.