Glabellar Botulinum Toxin Injections in Major Depressive Disorder: A Critical Review.

OBJECTIVE: To provide a critical appraisal of the primary clinical trials exploring the use of glabellar botulinum toxin type A (BTA) injections in the treatment of major depressive disorder (MDD) and propose future directions for research on this topic.

DATA SOURCES: A search in PubMed, Scopus, and Google Scholar databases was performed in September 2017. Search terms included ("botulinum" OR "botox" OR "abobotulinumtoxin" OR "onabotulinum" OR "onabotulinumtoxin" OR "botulinumtoxin") AND ("antidepressant" OR "depression" OR "depressive" OR "depressed"). No other search parameters were utilized.

STUDY SELECTION: Studies were selected for review if they were found to be a primary clinical trial on the use of BTA for the treatment of MDD.

DATA EXTRACTION: Six studies were identified and scored by the authors using a 5-point Jadad scoring system.

RESULTS: Three of the 6 studies were found to be of high quality with a Jadad score ≥ 3. The remainder had Jadad scores of 1.

CONCLUSIONS: In general, the results from the reviewed studies suggest that BTA may be a promising treatment for MDD. However, these findings need to be interpreted with caution due to several limitations of the reviewed studies such as lack of a priori hypotheses, limited sample sizes, large gender bias, and significant difficulty in ensuring blinding.