EEG Prediction and Clinical Efficacy of tDCS in Fibromyalgia.

Inclusion Criteria: * Patients who meet the diagnostic criteria described by the American College of Rheumatology (Wolfe et al., 2016): * Widespread Pain Index (WPI) ≥7 and Symptom Severity Scale (SSS) score ≥5 or a WPI score of 4-6 and SSS ≥9 * Presence of widespread pain, defined as pain in at least 4 of 5 regions. Jaw, chest, and abdominal pain are not included in the definition of widespread pain. * Symptoms have been generally present for at least 3 months. * The diagnosis of fibromyalgia (FM) is valid regardless of other diagnoses. The diagnosis of FM does not exclude the presence of other clinically significant diseases. * Patients with a stable prescription (or lack thereof) for antidepressant/pharmacological medication and who agree to continue it throughout the study. * Demonstrate the ability to properly administer home-based tDCS independently or with the assistance of a caregiver. * Have access to an electronic device with a camera (mobile phone or computer) to allow for monitoring of the intervention and communication with the participant. * Have the capacity and willingness to commit to the study team for the completion of all phases of the study. * Volunteer to participate and sign the specific informed consent form for this study. Exclusion Criteria: * Presenting with immune system disorders or comorbidities that explain the main symptoms of fibromyalgia: rheumatoid arthritis, lupus, autoimmune, neurological, and oncological disorders. * Presenting with an…