A prospective, randomized, double-blinded, placebo-controlled, two-arm trial was conducted at the Department of Psychiatry, General University Hospital in Prague, Czechia. The research was conducted in accordance with the Declaration of Helsinki and was approved by the Ethics Committee of General University Hospital in Prague, Czechia, in 2019 under the reference number 531/19 S-IV.~Participants were recruited through the recruitment campaign of the Department of Psychiatry, which was supported by outpatient services of several neurological, psychiatric, internal, and otorhinolaryngological departments in several university hospitals around Prague. All participants were required to sign written consent with the trial, anonymized data, the European Union General Data Protection Regulation (GDPR), and were fully informed about the trial's goals, risks, and requirements. Participation was not associated with any financial reward.~The participation was offered to persons at least 18 years of age (on the day of signing the consent) with a history of tinnitus lasting at least six months. The investigators excluded persons contraindicated to tDCS - such as those with epilepsy, intracranial masses or metallic objects, pregnancy, and heart conditions. The investigators also excluded persons with a history of alcohol and drug abuse, persons unwilling to sign the informed consent or persons who underwent any other tinnitus therapy in the last six months. The investigators intended to discontinue the treatment in any participant developing any severe adverse effect (significant exacerbation of tinnitus, epileptic seizure, severe headache, or any adverse effect deemed severe enough by the participants) and in participants noncompliant or unwilling to participate further with the trial and its follow-ups. The investigators required the participants not to alter their medication at least six months before the trial if any was used.
The study was designed to evaluate a therapeutic effect of tDCS in the treatment of tinnitus and its comorbidities (anxiety, depresion) and to evaluate the associated quality of life.~In the randomized, double-blinded, sham-controlled trial, 39 participants (active n=19, sham n=20) underwent bilateral dorsolateral prefrontal cortex (DLPFC) tDCS (anode over right DLPFC, cathode left DLPFC, current of 1.5 mA, 20 minutes, 6 sessions in 2 weeks). Tinnitus Functional Index (TFI), Iowa Tinnitus Handicap Questionnaire (ITHQ), Beck Anxiety Inventory (BAI), Zung Self-Rating Depression Scale (SDS), and WHO-Quality of Life-BREF were employed in 4 evaluation points, including the follow-ups of 6 weeks and six months.