Inclusion Criteria:  History of COVID-19 condition at least 4-6 weeks prior to study inclusion Self-reported concerns regarding cognitive functioning. Age: 18-60 years.  Exclusion Criteria:  Acute COVID-19 illness. History of dementia before COVID-19. Other neurodegenerative neurological disorders; epilepsy or history of seizures. Severe and untreated medical conditions that preclude participation in the training, as determined by responsible physician. History of severe alcoholism or use of drugs. Severe psychiatric disorders such as severe depression (if not in remission) or psychosis. Contraindication to tDCS application (Antal et al. 2017).