Transcranial Direct Current Stimulation for Fatigue, Mood, and Cognition in Multiple Sclerosis

Inclusion Criteria: * Age 18-55 years at the time of enrollment * Clinical diagnosis of Relapsing Multiple Sclerosis (RMS) or Progressive Multiple Sclerosis (PMS), with or without active progression, established per the 2014 McDonald diagnostic criteria * Expanded Disability Status Scale (EDSS) score of 0-3 at the time of screening * Time since initial MS diagnosis of at least 6 months * Active fatigue symptoms reported by the participant for at least the 6 months prior to enrollment Exclusion Criteria: * History of neuropsychiatric illness (including major depression, bipolar disorder, schizophrenia, or any anxiety disorder) prior to the onset of multiple sclerosis * Diagnosis of neuromyelitis optica spectrum disorder (Devic's disease) * Presence of any other central nervous system disease * Disease duration greater than 10 years combined with an EDSS score of ≤ 2 * Visual impairment secondary to optic neuritis, internuclear ophthalmoplegia (oculomotor disorder), or any other uncorrected visual impairment that would affect task performance on cognitive assessments * Current pharmacological treatment for fatigue or depression * Current neuropsychiatric pharmacological treatment, including any antidepressant, anxiolytic, neuroleptic, or anticonvulsant medication * Clinical relapse requiring corticosteroid treatment in the 3 months prior to enrollment * Severe upper-limb motor deficit that would prevent task performance on neuropsychological assessments