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.
This study is a randomized, single-blind, sham-controlled, crossover exploratory trial that plans to enroll 30 inpatients with schizophrenia, randomized 1:1 into two groups, with all participants receiving one active and one sham tACS session in a crossover manner separated by a 7-day washout. Stimulation targets the parietal P3/P4 sites at individual alpha frequency, with an intensity of 2 mA and a duration of 30 minutes per session, delivered concurrently with a working memory task (SIRP). Primary outcomes are SIRP accuracy and reaction time, with concurrent task-state EEG recording, along with assessments of clinical symptoms, cognitive function, and neurophysiological markers including ASSR, MMN, and P300. The study aims to explore the efficacy and underlying neural mechanisms of individualized alpha-tACS in improving working memory in schizophrenia.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
30
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 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.
The Second Xiangya Hospital of Central South University
Changsha, Hunan, China
RECRUITINGWorking Memory Accuracy
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.
Time frame: 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.
Working Memory Reaction Time
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.
Time frame: 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.
Changes in MCCB Performance
Assessment of cognitive function using the MATRICS Consensus Cognitive Battery (MCCB), a standardized cognitive assessment tool designed for schizophrenia and other neuropsychiatric conditions. The MCCB evaluates 9 cognitive domains: attention, information processing speed, verbal learning and memory, visual learning and memory, spatial working memory, reasoning and problem solving, social cognition, executive function, and fine motor skills. The overall cognitive composite score ranges from 20 to 100 (T-score), with higher scores indicating better cognitive performance.
Time frame: Baseline, on the day after each of the two interventions
Changes in Positive and Negative Symptom Scale (PANSS) Scores
Scores range from 30 to 210, with higher scores indicating more severe positive and negative symptoms.
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.
Time frame: Before and one week after each of the two interventions.
Changes in Scale for the Assessment of Negative Symptoms (SANS) Scores
Scores range from 0 to 120; higher scores indicate more severe negative symptoms.
Time frame: Before and one week after each of the two interventions.
Changes in Calgary Depression Scale for Schizophrenia (CDSS) Scores
Scores range from 0 to 27; higher scores indicate more severe affective symptoms.
Time frame: Before and one week after each of the two interventions.
Changes in Brain Function
Functional magnetic resonance imaging (fMRI), based on blood oxygen level-dependent (BOLD) contrast, can detect changes in blood oxygenation and analyze changes in brain function after intervention.
Time frame: Baseline, on the day after each of the two interventions.
Changes in Neuroelectrophysiological Signals
Changes in neuroelectrophysiological signals are collected through task-based electroencephalography (EEG).
Time frame: Baseline, 30 minutes after each of the two interventions.
Changes in 40Hz Auditory Steady-State Response (40Hz-ASSR)
The 40Hz auditory steady-state response recorded by EEG, including evoked power and inter-trial phase coherence, will be measured. The unit of measurement for evoked power is μV², and for coherence is unitless.
Time frame: Baseline, 30 minutes after each of the two interventions.
Changes in Mismatch Negativity (MMN)
Mismatch negativity amplitude recorded by EEG using an oddball paradigm will be measured. The unit of measurement is microvolts (μV).
Time frame: Baseline, 30 minutes after each of the two interventions.
Changes in P300 Event-Related Potential
P300 amplitude recorded by EEG using an oddball paradigm will be measured. The unit of measurement is microvolts (μV).
Time frame: Baseline, 30 minutes after each of the two interventions.
Hallucination and Delusion Visual Analog Scale (HD-VAS) Score
Assessment of acute post-intervention changes in hallucination and delusion severity using a patient-rated visual analog scale (VAS). The scale consists of a 0-100 mm horizontal line, on which participants mark their current symptom severity. The distance (in millimeters) from the left anchor ("no symptoms") to the participant's mark is measured with a ruler. This scale serves as a supplementary measure to the PANSS to capture immediate symptom changes following each intervention. Scores range from 0 to 100 mm, with higher scores indicating more severe hallucinations and delusions.
Time frame: Within 15 minutes after completion of Session 1; within 15 minutes after completion of Session 2.