Psychologists have long thought that the simple act of smiling actually makes you feel better. Now scientists have reported to the British Psychological Society that if you cannot frown and put on an angry or sad expression that you might not actually feel as angry or sad.

They tested one group of patients who had recently received BOTOX for their frown muscles against another group who had not received BOTOX. The BOTOX group had less brain activity when they tried to put on an angry expression than the non treated group.

So it is probable that facial expression has an effect on mood as well as the other way around. This improvement in mood will likely only be effective while the BOTOX remains effective.

Source: http://bps-research-digest.blogspot.com/search?q=Botox

Botox is Botulinum toxin. It works by temporarily paralyzing the muscles that it is injected into. It is made into precise units. It takes 3 to 7 days to become effective. It works for about 4 months.

While the muscle is inactive it loses bulk (becomes atrophic). When it recovers it gets its bulk back and gets strong again. If you add Botox before it recovers the muscle never has a chance to bulk up again. It will continue to lose bulk and eventually will find it more difficult to recover. So, after repeated treatments it seems logical that Botox may be able to weaken the muscle for longer and be more effective.