Dementia and Cognitive Decline in Schizophrenia: A Scoping Review Protocol

Objective: To map and describe the extent and nature of existing evidence on cognitive decline and dementia diagnoses among people with schizophrenia-spectrum disorders, including their historical context, epidemiology, definitions, proposed mechanisms, risk factors, and genetic or biomarker correlates. Introduction: Schizophrenia is a chronic psychiatric disorder associated with long-term cognitive deficits. Evidence suggests that people with schizophrenia (PwS) have an increased risk of developing dementia as they age, though its prevalence, mechanisms, and definitions remain unclear. Clarifying these aspects is essential to guide future research and clinical understanding. Inclusion criteria: Any study involving adults diagnosed with schizophrenia or related spectrum disorders that examines dementia, cognitive decline consistent with dementia, or associated neuropathological or biomarker findings will be included. All study designs and settings will be considered, including quantitative, qualitative, mixed-methods, review, and opinion papers. No date or language restrictions will be applied, although an English abstract will be required for screening. Methods: The review will follow the JBI methodology for scoping reviews using a three-step search strategy. An initial limited search will be undertaken in PubMed to identify relevant keywords and index terms. The final search will be conducted across PubMed, Cochrane Library, Web of Science, and PsycINFO using a broad strategy to capture studies examining the relationship between schizophrenia and dementia. Reference lists of included studies will also be screened for additional sources.