Home-Based Transcranial Direct Current Stimulation (tDCS) for Depression in Multiple Sclerosis (MS)

Inclusion Criteria: * Age: 18-65 years (inclusive) * Diagnosis: Confirmed diagnosis of multiple sclerosis (MS), including relapsing-remitting or secondary progressive subtypes * Stable Medications: Stable use of antidepressant and disease-modifying therapies (DMTs) for at least 30 days prior to enrollment * Stable Disease Activity: Defined as no clinical relapse, no new radiological disease activity, and no recent steroid treatment for at least 30 days prior to enrollment * Provider Contact: Confirmed access to a local provider that has primary responsibility for the subjects' clinical care, and who is available for contact in case of increased subject risk due to depressive symptoms * Technical Ability: Ability to use mobile devices and participate in remote, video-supervised sessions Exclusion Criteria: * Neurological or Medical Disorders: History of primary neurological disorder other than MS (e.g., stroke, Parkinson's disease, traumatic brain injury (TBI), intracranial mass, epilepsy, mild cognitive impairment (MCI), dementia), major psychiatric disorders (e.g., bipolar disorder, psychotic disorders), or serious medical conditions (e.g., myocardial infarction, thyroid disease, diabetes with complications, atrial fibrillation) * Substance Use: Nicotine use (e.g., smoking or vaping) within the past 6 months * Pregnancy and Breastfeeding: Currently pregnant, planning pregnancy during the study period, or breastfeeding. If able to become pregnant, participants will be required to use medically accepted birth control methods, including hormonal methods (e.g., pills, patches, implants), barrier methods (e.g., condoms or diaphragm with spermicide), intrauterine device (IUD), or abstinence. Participants will be advised not to become pregnant during the study. * Seizure History: History of seizures or seizure disorder within the past 5 years * Implanted Devices or Metal Objects: Presence of metal in the head/neck area (excluding dental fillings) or implanted medical devices (e.g., neurostimulators, pacemakers, defibrillators) * Skin Conditions: Active skin disorders or skin sensitivity near electrode application sites