Effects of transcranial direct current stimulation on COVID-19 neurological symptoms: a mini-review
Authors:   Instituto D’Or de Pesquisa e Ensino, Rio de Janeiro, Brazil, Pereira Monteiro Thais , Arceo Angelica ,   Dresden International University, Dresden, Germany, Bonifacio Ricardo ,   Hospital  Sírio-Libanês,  Instituto  de  Ensino  e  Pesquisa,  São  Paulo, Brazil, Anderson Roseli ,   Universidade Federal de São Paulo -UNIFESP, Diadema, Brazil, Pichardo Angie ,   Pontificia Universidad Católica Madre y Maestra, Santiago de  los Caballeros, Santiago, Dominican Republic, Garnier Justyna ,   SWPS  University  of  Social  Sciences  and  Humanities,  Warsaw, Poland, Gomide de Paula Lucas Guilherme ,   Faculdade São Leopoldo Mandic, Campinas, Brazil, Garlisi Torales Luciana Daniela ,   Facultad  de  Medicina,  Universidad  Maria  Auxiliadora, Asuncion, Paraguay, Lerro Lucas ,   University of Santo Amaro, São Paulo, Brazil, Elzubair Mohamed Khalil Malaz ,   Hamad Medical Corporation, Doha, Qatar, Moncada Denisse ,   Beth Israel Deaconess Medical Center,Boston, USA, dos Santos Lucas ,   Hospital Alemão Oswaldo Cruz, São Paulo, Brazil, Barco Guillen Astrid Carolina ,   Universidad de Especialidades Espíritu Santo, Guayaquil, Ecuador, Medina Amaro ,   Servicio de Rehabilititacion, Hospital Universitario Insular de Gran Canaria, Spain, Delgado Alvaro ,   Beth Israel Deaconess Medical Center,Boston, USA, Almarzoky Abuhussain Safa ,   Clinical Pharmacy department, Pharmacy, Umm AlQura University, Saudi Arabia, Maximiano de Oliveira Sandra ,   Rheumatology Division, Escola Paulista de Medicina, Universidade Federal de São Paulo -UNIFESP, São Paulo, Brazil
Published: July 2023

Introduction: COVID-19 patients can experience long-term effects including neurological symptoms as part of the long COVID syndrome. The most common neurological symptoms associated with this syndrome are cognitive impairments, such as brain fog, memory issues or loss of concentration, and mood changes, such as depression and anxiety. Non-invasive brain stimulation, for instance, transcranial direct current stimulation (tDCS), is a treatment currently being tested to improve cognitive deficits and mood disorders in long COVID. Methods: We performed a systematic literature search for articles on long COVID and non-invasive brain stimulation. Electronic searches were performed in MEDLINE (via PubMed) and Cochrane databases. The Joanna Briggs Institute Critical Appraisal tool was used for quality assessment. Data regarding population, intervention, outcomes, study design, and sources of funding were collected. Results: The search returned 21 articles, of which two case reports were included in the discussion. Three patients with long COVID and cognitive symptoms were treated with tDCS. Although these studies reported promising results, they had methodological differences, no control groups were used and the sample size is insufficient to draw definitive conclusions. Discussion: Neuromodulation treatments like tDCS are currently being considered to treat long COVID, since they have been found to improve cognition, but so far only in observational studies with few patients. In the future, randomized clinical trials using tDCS for long COVID patients with cognitive impairment might demonstrate the effectiveness of this intervention.