From Medscape Medical News
Daniel M. Keller, PhD
March 13, 2012 (Prague, Czech Republic) — For patients with chronic major depression that does not sufficiently respond to other treatments, a single injection of botulinum neurotoxin into the glabellar muscle of the forehead to relieve frown lines appears to lead to strong and sustained improvement of the depression.
Tillmann Kruger, MD, Associate Professor in the Department of Psychiatry, Social Psychiatry and Psychotherapy at Hannover Medical School in Hannover, Germany, reported here at the 20th European Congress of Psychiatry that these findings support the concept that facial musculature not only expresses mood states but also affects mood.
He explained that frowning expresses negative emotions such as anger, fear, or sadness. A facial feedback hypothesis says that the frown itself reinforces negative emotions, with the implication that suppressing frowning will help to relieve the negative emotions.
"The theory is pretty old, and it says that many or most of the emotions we have develop somewhere in the brain, and some of them are expressed in your face, for example...and this is again received and sent back to the central nervous system by this proprioceptive feedback," he told Medscape Medical News. He said that in some cases of depression, there are signs of increased glabellar muscle activity.
Facial Feedback Theory
"Not all glabellar frown lines have to disappear to guarantee a good psychological effect," Dr. Kruger said, and full remissions have been observed in patients with residual frown lines.
"We think, regarding possible mechanisms, that the reduced proprioceptive feedback — the facial feedback theory — is the most important one. I think this is something that works 24 hours per day," he added.
There may also be some effect of social feedback in that friends and family may tell patients that they do not look so angry.
Dr. Kruger said that botulinum is able to travel in a retrograde direction via nerve fibers to the central nervous system, but given the small amount of drug used, he thought this mechanism would not explain the effects seen.
However, when asked whether a more appropriate control than placebo injections would be botulinum injections into a cranial muscle that did not affect frowning, he agreed that such a procedure would be a good control for a possible effect of botulinum not related to the relief of frown lines. Therefore, it is still possible that botulinum acted through a mechanism other than relief of frown lines.
Dr. Kruger said the study also showed that botulinum injections had excellent safety and tolerability. "It may be even economic because it's only a single injection [session], and it works for more than 16 weeks, as we have seen," he said, but the study needs to be validated in larger trials.
At present, botulinum is not indicated for treatment of depression. "But Botox has an indication to treat glabellar frown lines...and if someone has frown lines and has a depression and says, 'I want to have them away, these frown lines,' you can, of course, use it," Dr. Kruger noted.
