transcranial alternating current stimulationsham stimulation
transcranial alternating current stimulation: For montage 1, active electrode at P3 (10-10 system), return electrodes at P1, P5, PO3, CP3. For montage 2, active electrode at P4, return electrodes at P2, P6, PO4, CP4. Conductive paste ensures impedance \<10 kΩ. Individual alpha frequency is used, calculated before each session from mean EEG at P3/P4 during SIRP task. Stimulation intensity is 2 mA (peak-to-zero) via electric field modeling. Stimulation is delivered during SIRP task, 30 min total per session (including 15s ramp-up/down), with continuous sine wave output.
sham stimulation: Sham stimulation provides only a 15-second ramp-up and ramp-down current at the beginning and end of each session to mimic the initial tingling or itching sensation on the scalp produced by real stimulation, but delivers no effective stimulation current during the main phase of the task period.
Study summary
This study is a randomized, single-blind, sham-controlled crossover trial enrolling 30 schizophrenia patients, each receiving one active and one sham tACS session (7-day washout), targeting P3/P4 at individual alpha frequency (2mA, 30min) during a working memory task, with accuracy and reaction time as primary outcomes, alongside EEG and neurophysiological measures, to test the efficacy and mechanisms of individualized alpha-tACS on working memory.
Eligibility
Sex
ALL
Min age
18 Years
Max age
50 Years
Healthy volunteers
No
Inclusion Criteria:
* Aged 18-50 years, meeting the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) diagnostic criteria for schizophrenia, confirmed by the Structured Clinical Interview for DSM-5 (SCID-5).
* Spatial span T-score \<40 on the MATRICS Consensus Cognitive Battery (MCCB).
* Taking 1-2 antipsychotic medications, with stable dosage for at least 1 week prior to enrollment. No use of mood stabilizers, antidepressants, or excessive benzodiazepines (lorazepam equivalent \>2 mg/day). The type and dosage of antipsychotic medications remain unchanged during the treatment period.
* Impaired functioning in daily activities.
* Willing to participate in this study and provide written informed consent.
Exclusion Criteria:
* Previously diagnosed with or comorbid any other DSM-5 mental disorder besides schizophrenia.
* Presence of significant mood symptoms or substance use disorder (other than caffeine and/or tobacco).
* Presence of any contraindication to transcranial alternating current stimulation (tACS).
* Received other forms of electrical or magnetic stimulation therapy within 1 month prior to enrollment.
* History or current presence of any major physical illness, neurological disorder, or traumatic brain injury that may affect brain structure or function.
* Pregnant or breastfeeding women, or women planning to become pregnant during the study period.
Primary outcome measure(s)
Working Memory Accuracy — Day 1 (baseline, prior to first intervention); within 15 minutes after Session 1; Day 9 (prior to second intervention, after 7-day washout); within 15 minutes after Session 2. Assessment of task accuracy on the Sternberg Item Recognition Paradigm (SIRP). Participants are required to judge whether a probe stimulus belongs to a previously memorized set, with memory set sizes of 1 and 5. The outcome is measured as the percentage of correct responses (0-100%) across all trials, with higher scores indicating better working memory performance.
Working Memory Reaction Time — Day 1 (baseline, prior to first intervention); within 15 minutes after Session 1; Day 9 (prior to second intervention, after 7-day washout); within 15 minutes after Session 2. Assessment of response speed on the Sternberg Item Recognition Paradigm (SIRP). Participants are required to judge whether a probe stimulus belongs to a previously memorized set, with memory set sizes of 1 and 5. The outcome is measured as the mean response latency for correct responses only, calculated from stimulus onset to the participant's button press, with shorter times indicating faster processing speed.
Trial sites (1)
Facility
City
Region
Status
The Second Xiangya Hospital of Central South University
This page summarises publicly available registry data for informational purposes — not medical advice. Eligibility is determined by each study team; patients should discuss participation with their clinician.
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