A Protocol for the Study of Environmental Risk Factors and Candidate Gene–environment Interactions in Neurodegenerative Disorders in Nigeria (SERGEND): A Cross-Sectional Descriptive Study

Introduction: The risk of developing neurodegenerative disorders (NDDs) such as Alzheimer’s disease and related dementias (ADRD) and Parkinson’s disease and atypical parkinsonism (PDAP), has been alluded to arise predominantly from the interplay between environmental exposures and genetic variability. The contributions of these factors to NDD in Black sub-Saharan Africans are largely unknown. The broad aim of SERGEND is to investigate the effect of specific environmental exposures and genetic variability on the risk of developing ADRD and PDAP in our population. Methods: The SERGEND, a national, multi-center, cross-sectional, descriptive study, will be conducted in Nigeria, within academic hospitals located in all six geopolitical zones of the country. The study population will comprise 3000 consenting adult Nigerians aged 18 years and above, residing within the recruiting geopolitical zone in the preceding 12 months. Cases will be persons with ADRD or PDAP and age-matched healthy controls. Assessments will include dementia and parkinsonism-specific case ascertainment, disease severity, functional status, and environmental risk factors assessment. Genotyping for APOE and SNCA REP1 polymorphic variability will be conducted. Future analyses will be performed on biobanked samples. Ethics and Dissemination: The study protocol was approved by the National Health Research Ethics Committee in Nigeria, with institutional HREC concordant approval for all participating sites before enrollment of the study participants. Written informed consent was obtained from all study participants or identified proxies. The study results will be published in peer-reviewed journals and as conference abstracts. Trial Registration: International Standard Registered Clinical/soCial sTudy Number (ISRCTN) registry (www.isrctn.com). Trial registration number: ISRCTN10548575. Locator ID: https://doi.org/10.1186/ISRCTN10548575.