Transcranial Direct Current Stimulation in Patients with Anxiety: Current Perspectives

Abstract

Anxiety is one of the most prevalent and debilitating psychiatric conditions worldwide. Pharmaco- and psycho-therapies have been employed in the treatment of human anxiety to date. Yet, either alone or in combination, unsatisfactory patient outcomes are prevalent, resulting in a considerable number of people whose symptoms fail to respond to conventional therapies with symptoms remaining after intervention. The demand for new therapies has given birth to several noninvasive brain stimulation techniques. Transcranial direct current stimulation (tDCS) has arisen as a promising tool and has been proven to be safe and well tolerated for the treatment of many diseases, including chronic pain, depression, and anxiety. Here, reports of the use of tDCS in anxiety disorders in human patients were reviewed and summarized. A literature search was conducted in mid-2019, to identify clinical studies that evaluated the use of tDCS for the treatment of anxiety behavior. The PubMed, Web of Science, and Scielo and PsycInfo databases were explored using the following descriptors: "anxiety", "anxious behavior", "tDCS", and "transcranial direct current stimulation". Among the selected articles, considerable variability in the type of tDCS treatment applied in interventions was observed. Evidence shows that tDCS may be more effective when used in combination with drugs and cognitive behavioral therapies; however future large-scale clinical trials are recommended to better clarify the real effects of this intervention alone, or in combination with others.

Keywords: anxious behavior; clinical research; humans; psychiatric disorder; transcranial electrical stimulation.

Figure 1

(A) Schematic representation of dysfunctional cortical brain regions in anxiety patients: hyperactivation of right and/or hypoactivation of left frontal cortical regions produce negative emotions. (B) Most common used montage of electrode placement for the treatment of anxiety: modulation of brain activity using tDCS (cathode right, anode left) improves anxiety symptoms by regulating the balance of brain activity. Abbreviations: GAD, Generalized Anxiety Disorder; DLPFC, Dorsolateral Prefrontal Cortex; VLPFC, Ventrolateral Prefrontal Cortex.