Experimental: Active taVNS

Patients will undergo 15 sessions of 30-min active taVNS applied to the cymba conchae of the left ear. Clinical assessments-including symptom severity questionnaires and neuropsychological tests-along with neurophysiological recordings (hd-EEG and electrocardiography) will be conducted on the first (S1) and final (S15) days of the intervention. The remaining 13 sessions (S2-14) will be self-administered by patients at home.~To monitor safety, participants will report any side effects after each session.~To monitor adherence, the device will record the time and duration of each stimulation session. Blinding efficacy will be evaluated at the end of the intervention by asking participants to indicate whether they believe they received active or sham stimulation, and to rate their confidence in that response.~A follow-up assessment will occur one month after the intervention, during which symptom severity questionnaires will be administered via a phone interview.

Sham_comparator: Sham taVNS

Patients will undergo 15 sessions of 30-min sham taVNS applied to the cymba conchae of the left ear. Clinical assessments-including symptom severity questionnaires and neuropsychological tests-along with neurophysiological recordings (hd-EEG and electrocardiography) will be conducted on the first (S1) and final (S15) days of the intervention. The remaining 13 sessions (S2-14) will be self-administered by patients at home.~To monitor safety, participants will report any side effects after each session.~To monitor adherence, the device will record the time and duration of each stimulation session. Blinding efficacy will be evaluated at the end of the intervention by asking participants to indicate whether they believe they received active or sham stimulation, and to rate their confidence in that response.~A follow-up assessment will occur one month after the intervention, during which symptom severity questionnaires will be administered via a phone interview.