Emotional Anatomy: Botulinum Toxin and the Regulation of Mood

Purpose: Emotions are expressed via coordinated contraction of the small muscles of the face to convey psychological expression. Manipulation of this coordinated movement can affect the emotions that patients experience and results in an influence of limbic system activity. Botulinum toxin is the most popular cosmetic procedure for correction of contraction-associated fine lines and wrinkles, and acts via temporary muscle relaxation. This review explores the effects that botulinum toxin has on specific muscle groups and thereby on emotional expression and feeling. Methods: A literature review regarding understanding of facial anatomy and expressions as well as botulinum toxin’s effect on emotions and communication was conducted via PubMed using search terms such as “botulinum toxin” AND “emotion”. Results were screened for relevance and to include English-only articles. Further articles were included through citation tracking. Authors’ clinical experience was also included. Results: A total of 50 articles were included based on relevance and search terms. Two additional book chapters were added from author knowledge. Biological feedback from the facial feedback, facial mimicry, and emotional contagion are the basis of botulinum toxin-induced emotional influence. The paralysis of muscles associated with frowning (glabellar complex) and smiling (zygomaticus and orbicularis oculi) as a treatment for wrinkles and fine lines can result in patients experiencing more or less positive or negative emotions, depending on which muscles are targeted. Patients treated in the glabellar region only with botulinum toxin reported significant increases in their mood, which was attributed to their acquired inability to produce a frown. This included clinically depressed patients who experienced a significant improvement in depression scores or resolution of depression altogether. Treatment of the “crow’s feet” region canceled the glabella effect when treated alone, resulting in a more negative mood. Conclusions: Facial expressions can influence mood states and perception of emotions. Although known traditionally as a cosmetic treatment, botulinum toxin can also be used to influence patient mood via facial muscle paralysis, and importantly, offers an alternative treatment modality for depression.