Several classic studies demonstrate that activation of specific facial muscles (e.g., clenching a pencil between one’s teeth to activate the smiling muscles) can alter mood. These researchers examined whether clinical improvement is associated with decreased depressive facial expression through the use of botulinum toxin type A in the glabellar region.
Inclusion criteria were ongoing major depressive disorder, Hamilton Rating Scale for Depression (HRSD) score of 15 or higher, and a moderate-to-severe vertical glabellar line during maximum frowning. Patients were taking one or two antidepressants or had not responded to at least one previous antidepressant. The investigators assessed 263 patients for eligibility and accepted 30 (23 women; average age, 51; mean HRSD, 20; illness duration, 16 years; current episode, 29 months). Patients received injections of botulinum toxin or placebo and were assessed biweekly.
To mask treatment assignment, patients wore caps covering the affected area during assessments. HRSD scores significantly improved at 6 weeks in the active group (HRSD change, –10.07 vs. –1.73 with placebo; response rate [
50% decrease in HRSD], 60% vs. 13%). The treatment was identified by 60% of raters and 90% of subjects. Opinion about the cosmetic change was not linked to response.
Comment : These thought-provoking results raise a skeptical eyebrow. Very few screened subjects were enrolled, and group assignment was obvious. The authors claim that exclusion rates were high because of psychiatric comorbidity, medication history, and patient refusal (recruitment information did not identify the protocol). Still, in these subjects with moderate and chronic major depressive disorder unresponsive to at least one medication, botulinum toxin demonstrated an effect similar to medication and greater than transcranial magnetic stimulation. The results appear to confirm the connection between facial expression and feelings. Botulinum toxin may have a therapeutic role in depression, although larger clinical trials are necessary to confirm this initial finding.
— Jonathan Silver, MD
Published in Journal Watch Psychiatry 2012