This randomized, double-blind, sham-controlled trial aims to evaluate the efficacy and safety of dorsal anterior cingulate cortex-targeted temporal interference stimulation in individuals with schizophrenia. Participants will be randomly assigned to receive either active or sham stimulation for 10 sessions over two consecutive weeks. The primary outcome is the change in negative symptoms, assessed using the Negative Symptom Subscale of the Positive and Negative Syndrome Scale. Cognitive performance, detailed dimensions of negative symptoms, psychosocial functioning, quality of life, and treatment-related adverse events will also be evaluated. Neuroimaging assessments will be conducted before and after the intervention to explore potential neural mechanisms underlying the clinical effects of temporal interference stimulation.
A confirmed diagnosis of schizophrenia established according to the criteria set forth in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5);
Age between 18 and 65 years, regardless of sex, with completion of at least junior secondary education and the capacity to undergo neurocognitive testing;
Clinically meaningful negative symptoms, operationalized as a PANSS negative symptom subscale (PANSS-NS) total score ≥ 20 with a rating of ≥ 3 on a minimum of one individual PANSS-NS item ; the PANSS positive symptom subscale score must additionally not exceed 19;
Objective cognitive impairment evidenced by an age- and sex-adjusted composite z-score of ≤ -1.0 on the Chinese version of the Brief Assessment of Cognition in Schizophrenia (BACS), reflecting performance at least one standard deviation below normative values derived from Mandarin-speaking populations;
A concurrent psychiatric diagnosis requiring active clinical management, including but not limited to major depressive episode or bipolar disorder, or the presence of a comorbid neurological disorder or serious physical illness;
Current or past substance use disorder, encompassing problematic consumption of alcohol or illicit substances;
A documented seizure disorder or marked electroencephalographic abnormalities, particularly epileptiform activity;
Evidence of structural brain pathology, including organic lesions, prior traumatic brain injury, or previous neurosurgical intervention;
Parallel
Temporal Interference Stimulation
DeviceParticipants will receive active temporal interference stimulation targeting the dorsal anterior cingulate cortex. Two high-frequency alternating currents at 2000 Hz and 2006 Hz will be delivered using an individualized electrode configuration determined by electric field modeling. Each session will last 30 minutes. Treatment will be administered five times per week for two consecutive weeks, for a total of 10 sessions.
Sham Temporal Interference Stimulation
DeviceParticipants will receive sham temporal interference stimulation using the same electrode placement and session schedule as the active stimulation group. Brief ramp-up and ramp-down periods will be applied to mimic the sensations associated with active stimulation, but sustained temporal interference stimulation will not be delivered. Each session will last 30 minutes. Treatment will be administered five times per week for two consecutive weeks, for a total of 10 sessions.
Change in the Positive and Negative Syndrome Scale Negative Symptom Subscale Score
The Positive and Negative Syndrome Scale Negative Symptom Subscale (PANSS-NS) consists of 7 items. Each item is rated from 1 to 7, yielding a total score ranging from 7 to 49. Higher scores indicate greater severity of negative symptoms. The change from baseline to immediately after the intervention will be compared between the active and sham stimulation groups.
Change in the Brief Assessment of Cognition in Schizophrenia Composite Score
The Brief Assessment of Cognition in Schizophrenia (BACS) is a multidomain battery assessing overall neurocognitive functioning, including verbal learning and memory, working memory, psychomotor speed, verbal fluency, sustained attention and processing speed, and executive function. The constituent subtests include the List Learning Test, Digit Sequencing Task, Token Motor Task, Category Instances and Controlled Oral Word Association Test, Symbol Coding Task, and Tower of London Test. Domain scores are aggregated into a single composite z-score standardized against age- and sex-matched normative data. Lower values reflect greater cognitive impairment.
Change in the Scale for the Assessment of Negative Symptoms Total Score
The Scale for the Assessment of Negative Symptoms (SANS) provides a detailed characterization of negative symptomatology. It comprises 25 clinician-rated items spanning five domains: affective flattening or blunting, alogia, avolition-apathy, anhedonia-asociality, and attentional impairment. Each item is rated on a six-point scale ranging from 0 to 5. The item scores are summed to generate a total score, where higher values denote a more severe negative symptom profile.
Change in the Apathy Evaluation Scale Total Scor
The Apathy Evaluation Scale (AES-S) is a self-rated measure used to evaluate apathy. The scale consists of 18 items that probe the cognitive, affective, and behavioral dimensions of apathetic experiences over the preceding four weeks. Responses are summed to yield a total score ranging from 0 to 72. Higher scores indicate more severe apathy, meaning a worse outcome.
Change in the Temporal Experience of Pleasure Scale Total Score
The Temporal Experience of Pleasure Scale (TEPS) is used to evaluate hedonic experience by separately indexing the anticipatory and consummatory components of pleasure. The scale consists of 20 items, with each item rated on a six-point Likert scale ranging from 1 ("very false for me") to 6 ("very true for me"). Following the reverse-scoring of designated items, responses are summed to yield a total score, where lower values indicate greater anhedonia. Therefore, higher scores indicate a better outcome.
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