Schizophrenia / Schizoaffective Disorder
Conditions
Brief summary
This clinical trial investigates whether a non-invasive brain stimulation technique called transcranial alternating current stimulation (tACS) can improve the ability to distinguish between "self" and "others" in patients with schizophrenia. The intervention targets the medial prefrontal cortex (mPFC), a brain region critical for self-awareness, using 10Hz stimulation at 2mA for 20 minutes daily over five consecutive days. The study has two main objectives. First, it aims to characterize the underlying mechanisms of self-other boundary dysfunction in schizophrenia by comparing behavioral and brain activity patterns among three participant groups: patients with schizophrenia, individuals with high schizotypal traits, and healthy volunteers. During this mechanism phase, participants perform two computer-based self-other face recognition tasks designed to manipulate prior probability (varying the proportion of self vs. other faces across blocks) and perceptual uncertainty (adjusting the Gaussian blur level of face images), while their brain activity is recorded via EEG. Behavioral performance (response time, accuracy, and sensitivity d') and EEG markers (alpha-band power, N170, and P1 components) are analyzed to quantify deficits in predictive coding. Second, the study aims to evaluate the therapeutic efficacy of tACS in a randomized, double-blind, sham-controlled trial. The primary hypothesis is that active tACS, compared to sham stimulation, will significantly improve patients' accuracy in distinguishing self from other faces, accompanied by enhanced alpha-band brain oscillations and reduced scores on the Examination of Anomalous Self-Experience (EASE) scale. All participants will undergo clinical assessments, complete the face recognition tasks while their brain activity is monitored via EEG, and complete follow-up assessments 48 hours after the last stimulation session. The findings from this study may provide a novel, mechanism-based non-pharmacological intervention for addressing core self-disturbance in schizophrenia, potentially improving patients' social functioning and quality of life.
Interventions
DEVICETranscranial Alternating Current Stimulation (tACS)
10Hz tACS with 2mA intensity, 20 minutes per day
Sham stimulation with identical electrode placement and procedures as the active tACS group. Current is delivered only during the 30-second ramp-up and ramp-down periods, with no active stimulation for the remainder of the 20-minute session.
Sponsors
Chunyan Zhu
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Investigator)
Eligibility
Sex/Gender
ALL
Age
18 Years to 50 Years
Healthy volunteers
No
Inclusion criteria
* Diagnosis of schizophrenia according to DSM-5 criteria * Presence of hallucinations or delusions * Age between 18 and 50 years * Clinically stable on a stable dose of antipsychotic medication for at least 4 weeks prior to enrollment, with no anticipated medication changes during the study period * Normal or corrected-to-normal vision (≥ 20/40) as assessed by standard visual acuity test * Able to understand and provide written informed consent
Exclusion criteria
* History of neurological disorders (e.g., epilepsy, stroke, traumatic brain injury) * Presence of other major psychiatric disorders (e.g., bipolar disorder, major depressive disorder) * Previous receipt of non-invasive brain stimulation (e.g., tACS, tDCS, rTMS) * History of substance dependence or abuse within the past 6 months * Metal implants in the head or skull (e.g., cochlear implants, deep brain stimulators) * Pregnancy or breastfeeding * Presence of skin lesions, wounds, or sensitive skin at electrode placement sites (Fpz, AF7, AF8, F5, F6)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Self-Other Face Recognition Sensitivity (d') | Baseline (pre-intervention) and 48 hours after the last tACS session | Change from baseline in the sensitivity index (d') measured by the self-other face recognition task at 48 hours after the last tACS session. Participants distinguish between self and other faces under varying prior probability and perceptual uncertainty conditions. The sensitivity index (d') is dimensionless; a higher value indicates better ability to differentiate between self and other faces. |
| Change in Medial Prefrontal Cortex Alpha-Band Oscillatory Power | Baseline (pre-intervention) and 48 hours after the last tACS session | Change from baseline in alpha-band (8-13 Hz) oscillatory power measured by electroencephalography (EEG) over the medial prefrontal cortex (mPFC) at 48 hours after the last tACS session. Alpha-band power is assessed during resting-state and self-other face recognition task performance to evaluate the neural effects of the intervention. |
Countries
China
Contacts
CONTACTlong chen
Outcome results
None listed