Introduction: Photobiomodulation (PBM) may alleviate cognitive disturbances in neurological and psychiatric disorders, potentially via improvements in brain metabolism and cerebral blood flow. This non-invasive approach may be beneficial for cognitive impairment associated with schizophrenia (CIS). We present a study protocol for an open-label trial evaluating the safety and tolerability of PBM in patients with schizophrenia. Patients and Methods: Patients with CIS will be recruited and receive PBM for 12 weeks (three sessions per week, 20 minutes per session). Eligibility criteria include a DSM-5 diagnosis of schizophrenia, age 18– 70 years, and having marked cognitive impairment (≤− 0.5 SD on the WAIS Digit Symbol Coding or Rey Auditory Verbal Learning Test). A total of 25 participants will be enrolled. Near-infrared light will be delivered using a multi-site system with transcranial and intranasal applicators. The primary outcome is safety and tolerability, assessed by the incidence and frequency of adverse events at baseline and at 1 week, 3 months, and 6 months after treatment initiation. Secondary outcomes include neurocognitive function, activities of daily living, social functioning, psychiatric symptoms, event-related potentials, and cerebral blood flow measured by near-infrared spectroscopy. Conclusion: This study will provide preliminary data on the safety and tolerability of PBM in Japanese patients with schizophrenia and explore its potential effects on CIS, informing future clinical trials. Ethics and Dissemination: The protocol was approved by the Clinical Research Review Board of the National Center of Neurology and Psychiatry (CR24-003) and registered with the Japan Registry of Clinical Trials (jRCT032240756). Keywords: photobiomodulation, schizophrenia, cognitive dysfunction, clinical trial protocol, open-label
Yamada et al. (2026) studied this question.