Does being unable to make a sad face ease the symptoms of depression? While vanity is typically the reason people get Botox, more than one study has shown that the substance may also help fight depression. For years, women and men have been turning to Botox, or botulinum toxin, to reduce the signs of aging. By paralyzing facial muscles, the substance makes wrinkles disappear -- temporarily. Botox is considered to be the most potent neurotoxin and can be deadly to humans above a certain dose. Although in small amounts Botox has the effect of paralyzing muscles, botulism is a deadly illness that can arise during accidental overdose. A person or animal that contracts botulism will experience paralysis, starting in the face and spreading out toward the appendages. In severe cases, breathing will be affected and respiratory failure can occur. Beginning in the 1970s, Botox was used to treat muscular eye conditions. In the late 1980s, doctors discovered that Botox could also be used to relax facial muscles, and, as a consequence, make wrinkles disappear. The Food and Drug Administration approved the use of Botox for cosmetic purposes in 2002. Using Botox as an anti-aging substance has become one of the most powerful tools in a cosmetic surgeon's arsenal. Each Botox injection can last up to six months, and, while not as permanent as a surgical intervention, requires little to no recovery time. Side effects of Botox can include droopiness of the eyelids or mouth or even double vision; these conditions are temporary, however, and usually resolve in a few weeks. A more surprising side effect, however, is that the toxin may make it impossible for a Botox user to read facial expressions in others by suppressing the mirror neurons. Mirror neurons are cells in the brain that fire both when we act and when we see someone else completing the same act. The best example of mirror neurons firing is when you see someone injure themselves and you cringe in response: you \u201cfeel" their pain. Another example would be when someone yawns and you yawn in response. If Botox prevents our mirror neurons from firing when we see someone smile or frown, we may not be able to determine which emotion they are feeling, and, more importantly, may not be able to feel the same emotion ourselves. A new study on Botox and emotions goes a step further than previous hypotheses. Instead of just blocking the ability to read emotion, Botox may play a part in treating mood disorders like depression. The study involved subjects who had been diagnosed with depression and had not experienced significant relief of symptoms after two years. Half of the subjects received Botox for frown lines and the other half received a placebo. More than 25% of patients who received the toxin reported that their symptoms of severe depression were alleviated; less than 10% of those who received the placebo reported a similar effect. The findings appear in the Journal of Psychiatric Research. Study author M. Axel Wollmer, a psychiatrist at the University of Basel in Switzerland, believes the treatment \u201cinterrupts feedback from the facial musculature to the brain, which may be involved in the development and maintenance of negative emotions. This new finding supports the concept that our facial muscles not only express, but also regulate, mood. Perhaps we are on our way to some sort of smile therapy as a way to elevate mood naturally.