Alcohol consumption and risk of dementia: A dose-response meta-analysis.

Objective: To investigate the relationship between alcohol consumption and the incidence of dementia.

Method: We will conduct a systematic search without language and year restrictions to identify all relevant published studies. The following electronic databases will be searched: PubMed, EMBASE, the Cochrane Library, Chinese BioMedical Literature Database (CBM) and China National Knowledge Infrastructure (CNKI), VIP, Wan-Fang. Cohort studies published in Chinese or English are considered for inclusion. Two authors will independently select studies base on inclusion criteria, extract data and assess the quality of included studies using the Newcastle-Ottawa Scale, the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) system will be used to quantify absolute effects and quality of evidence. Any disagreement will be resolved by consensus. We will use the hazard ratio (HR) as the effect indicator, piecewise linear regression model and restricted cubic spline model will be used for linear and nonlinear trend estimation, respectively.

Registration: The dose-response meta-analysis is registered in the PROSPERO (CRD42019127367) international prospective register of systematic review.

Discussion: In the previous related dose-response meta-analysis studies, there were some limitations: on the 1 hand, the sex was not taken into account. On the other hand, relative risk (RR) is not the best effect indicator for time-to-event data, but compare with RR, HR is much better. This study intends to use HR as the effect indicator to explore the dose-response relationship and the sex difference between alcohol intake and dementia. Accurate alcohol drinking data can provide high-quality evidence for the prevention of dementia.