Reduction of social anxiety symptoms with transcranial direct current stimulation: A case report

Social anxiety disorder (SAD) reaches a prevalence of 13% in the adult population [[1]Kessler R.C. Petukhova M. Sampson N.A. Zaslavsky A.M. Wittchen H.U. Twelve-month and lifetime prevalence and lifetime morbid risk of anxiety and mood disorders in the United States.Int J Methods Psychiatr Res. 2012; 21: 169-184https://doi.org/10.1002/mpr.1359Crossref PubMed Scopus (1352) Google Scholar], characterized by intense fear or anxiety in the face of social situations which leads to avoidance, and impaired quality of life [[2]American Psychiatric AssociationDiagnostic and statistical manual of mental disorders. fifth ed. 2013https://doi.org/10.1176/appi.books.9780890425596Crossref Google Scholar]. Drug and psychological treatment are the most common, but new interventions, such as the use of transcranial direct current stimulation (tDCS), have shown promising results [[3]Vicario C.M. Salehinejad M.A. Felmingham K. Martino G. Nitsche M.A. A systematic review on the therapeutic effectiveness of non-invasive brain stimulation for the treatment of anxiety disorders.Neurosci Biobehav Rev. 2019; 96: 219-231https://doi.org/10.1016/j.neubiorev.2018.12.012Crossref PubMed Scopus (69) Google Scholar]. tDCS is a non-invasive neurostimulation procedure, in which a low-intensity electrical current passes through the brain through two electrodes, promoting a change in cortical excitability [[4]Kronberg G. Bridi M. Abel T. Bikson M. Parra L.C. Direct current stimulation modulates LTP and LTD: activity dependence and dendritic effects.Brain Stimulation. 2017; 10: 51-58https://doi.org/10.1016/j.brs.2016.10.001Abstract Full Text Full Text PDF PubMed Scopus (127) Google Scholar]. Its effect on psychiatric disorders is a consequence of the induction of synaptic plasticity which occurs during and after the sessions and regulates the dysfunctional neuroplasticity of these disorders [[3]Vicario C.M. Salehinejad M.A. Felmingham K. Martino G. Nitsche M.A. A systematic review on the therapeutic effectiveness of non-invasive brain stimulation for the treatment of anxiety disorders.Neurosci Biobehav Rev. 2019; 96: 219-231https://doi.org/10.1016/j.neubiorev.2018.12.012Crossref PubMed Scopus (69) Google Scholar,[4]Kronberg G. Bridi M. Abel T. Bikson M. Parra L.C. Direct current stimulation modulates LTP and LTD: activity dependence and dendritic effects.Brain Stimulation. 2017; 10: 51-58https://doi.org/10.1016/j.brs.2016.10.001Abstract Full Text Full Text PDF PubMed Scopus (127) Google Scholar]. Thus, we report the case of G, 24 years old, female who presented a reduction in the symptoms of SAD after tDCS. G developed the disorder during adolescence with worsening of the condition in early adulthood. She does not present psychiatric or neurological comorbidities, she has never undergone drug treatment, and with cognitive-behavioral therapy she presented symptom resistance. Although G did not report any further details about the psychotherapy performed, she informed that her treatment did not follow the number of sessions and/or interventions of standardized protocols for SAD. Currently, the situations considered most anxiogenic are those of performance evaluation, such as meetings in small or large groups. In view of the persistence of her symptoms, she underwent tDCS sessions, after consent to the publication of her case. For stimulation, the anode was positioned in the left portion of the ventromedial prefrontal cortex (vmPFC; Fp1), and the cathode in the contralateral region (Fp2). Current intensity 2mA was used with 25cm2 electrodes. Each session lasted 20 minutes on 5 consecutive days. The tolerability of the intervention was assessed using the tDCS adverse effects questionnaire [[5]Brunoni A.R. Amadera J. Berbel B. Volz M.S. Rizzerio B.G. Fregni F. A systematic review on reporting and assessment of adverse effects associated with transcranial direct current stimulation.Int J Neuropsychopharmacol. 2011; 14: 1133-1145https://doi.org/10.1017/S1461145710001690Crossref PubMed Scopus (618) Google Scholar], and the symptoms with the Liebowitz social anxiety scale – self report version (LSAS-SR) [[6]Liebowitz M.R. Social phobia.Mod Probl Pharmacopsychiatr. 1987; 22: 141-173https://doi.org/10.1159/000414022Crossref PubMed Google Scholar], the social phobia inventory (SPIN) [[7]Connor K.M. Davidson J.R. Churchill L.E. Sherwood A. Foa E. Weisler R.H. Psychometric properties of social phobia inventory (SPIN): new self-rating scale.Br J Psychiatry. 2000; 176: 379-386https://doi.org/10.1192/bjp.176.4.379Crossref PubMed Scopus (872) Google Scholar], and an adaptation of the behavioral avoidance test (BAT) by Anderson et al. [[8]Anderson P.L. Price M. Edwards S.M. Obasaju M.A. Schmertza S.K. Zimand E. Calamaras M.R. Virtual reality exposure therapy for social anxiety disorder: a randomized controlled trial.J Consult Clin Psychol. 2013; 81: 751-760https://doi.org/10.1037/a0033559Crossref PubMed Scopus (148) Google Scholar]. In this test, a self-assessment of performance and anxiety was performed, and the heart rate variability (HRV) was monitored during a speech before an audience in virtual reality glasses. There was a 51% reduction in the LSAS score and 39% in the SPIN after the 5 days of intervention, and in the 15-day follow-up, a 71% reduction in the LSAS and 51% in the SPIN. There was also an improvement in performance, anxiety and HRV during BAT (see Table 1).Table 1Baseline, post-intervention and follow-up outcomes.BaselinePost-InterventionFollow-upLSAS1014929SPIN583528BAT self-assessmentAnxiety641Performance4810HRVHFaPower (ms2/Hz).162327262Note. LSAS = Liebowitz Social Anxiety Scale; SPIN = Social Phobia Inventory; BAT = Behavioral Avoidance Test; HRV = Heart Rate Variability; HF = High Frequency band, reflects parasympathetic activity.a Power (ms2/Hz). Open table in a new tab Note. LSAS = Liebowitz Social Anxiety Scale; SPIN = Social Phobia Inventory; BAT = Behavioral Avoidance Test; HRV = Heart Rate Variability; HF = High Frequency band, reflects parasympathetic activity. In order to evaluate the effect of the intervention through LSAS and SPIN, the reliable change index (RCI) and clinical significance were used, components of the JT method [[9]Jacobson N.S. Truax P. Clinical significance: a statistical approach to defining meaningful change in psychotherapy research.J Consult Clin Psychol. 1991; 59: 12-19https://doi.org/10.1037//0022-006x.59.1.12Crossref PubMed Scopus (0) Google Scholar] using criterion A and the following parameters: LSAS (m = 74.53; sd = 23.31); SPIN (m = 38.34; sd = 13.34). A reliable change was observed with reduced symptoms, but there was no clinically significant improvement, that is, the participant remained with SAD scores for the clinical population. Regarding the adverse effects, the participant reported 8 of the 11 effects of the questionnaire (headache, scalp pain, tingling, itching, burning sensation, redness of the skin, drowsiness and flashes), but with a reduction in the course of the sessions, and only soft flashes remained from the first to the last day. The scarcity of studies investigating the effects of tDCS on SAD limits the comparison of our findings. Only Heeren et al. [[10]Heeren A. Billieux J. Philippot P. De Raedt R. Baeken C. Timary P. Vanderhasselt M.A. Impact of transcranial direct current stimulation on attentional bias for threat: a proof-of-concept study among individuals with social anxiety disorder.Soc Cognit Affect Neurosci. 2017; 12: 251-260https://doi.org/10.1093/scan/nsw119Crossref PubMed Scopus (45) Google Scholar] investigated the effects of tDCS on people with SAD, this study used anodal stimulation to the left dorsolateral prefrontal cortex (dlPFC) of 19 women diagnosed with SAD. However, despite the positive results, it was not possible to conclude an improvement in the clinical condition disorder, since the objective of the study was to investigate the effect of tDCS on only one variable, the attentional bias. Another study [[11]Paes F. Baczynski T. Novaes F. Marinho T. Arias-Carrión O. Budde H. et al.Repetitive transcranial magnetic stimulation (rTMS) to treat social anxiety disorder: case reports and a review of the literature.Clin Pract Epidemiol Ment Health. 2013; 9: 180-188https://doi.org/10.2174/1745017901309010180Crossref PubMed Scopus (20) Google Scholar] used low frequency repetitive transcranial magnetic stimulation (rTMS) (similar to cathodic stimulation) in the right vmPFC of two participants, and also found evidence of reduced symptoms in the LSAS scores (patient A: 35%; patient B: 51%). The greater reduction in symptoms observed in our results may be related to the individual characteristics of the participants of both surveys, and the difference in the configuration of the sessions since Paes et al. [[11]Paes F. Baczynski T. Novaes F. Marinho T. Arias-Carrión O. Budde H. et al.Repetitive transcranial magnetic stimulation (rTMS) to treat social anxiety disorder: case reports and a review of the literature.Clin Pract Epidemiol Ment Health. 2013; 9: 180-188https://doi.org/10.2174/1745017901309010180Crossref PubMed Scopus (20) Google Scholar] performed 25min sessions, 3 times a week for 4 weeks. We also highlight the results of the evaluation of adverse effects, which apparently guarantee the safety of the technique. Despite the promising initial results, it is not clear in the literature and in this study, the possibility of standardizing a gold standard protocol for SAD, with issues such as the number and duration of sessions and the ways of evaluating the effectiveness of the technique remaining open. This case reveals that tDCS in vmPFC may be able to reduce the symptoms of SAD, and highlights the technique as an alternative for refractory cases or with low response to traditional treatments. Nevertheless, due to the absence of a control case, it is possible that the results obtained were generated by a placebo effect. Single case studies are exploratory, and little generalizable, but they open perspectives for the formulation of hypotheses, enabling subsequent investigations with other designs, thus, it is suggested that this intervention is replicated in a sample with a larger number of participants. We declare that the research was conducted in the absence of any commercial or financial relationships that could be constructed as a potential conflict of interest.