Science

Jin-Tai Yu, Wei Xu, Chen-Chen Tan, Sandrine Andrieu, John Suckling, Evangelos Evangelou, An Pan, Can Zhang, Jianping Jia, Lei Feng, Ee-Heok Kua, Yan-Jiang Wang, Hui-Fu Wang, Meng-Shan Tan, Jie-Qiong Li, Xiao-He Hou, Yu Wan, Lin Tan, Vincent Mok, Lan Tan, Qiang Dong, Jacques Touchon, Serge Gauthier, Paul S Aisen, Bruno Vellas

Background: Evidence on preventing Alzheimer’s disease (AD) is challenging to interpret due to varying study designs with heterogeneous endpoints and credibility. We completed a systematic review and meta-analysis of current evidence with prospective designs to propose evidence-based suggestions on AD prevention.
Methods: Electronic databases and relevant websites were searched from inception to 1 March 2019. Both observational prospective studies (OPSs) and randomised controlled trials (RCTs) were included. The multivariable-adjusted effect estimates were pooled by random-effects models, with credibility assessment according to its risk of bias, inconsistency and imprecision. Levels of evidence and classes of suggestions were summarised.
Results: A total of 44 676 reports were identified, and 243 OPSs and 153 RCTs were eligible for analysis after exclusion based on pre-decided criteria, from which 104 modifiable factors and 11 interventions were included in the meta-analyses. Twenty-one suggestions are proposed based on the consolidated evidence, with Class I suggestions targeting 19 factors: 10 with Level A strong evidence (education, cognitive activity, high body mass index in latelife, hyperhomocysteinaemia, depression, stress, diabetes, head trauma, hypertension in midlife and orthostatic hypotension) and 9 with Level B weaker evidence (obesity in midlife, weight loss in late life, physical exercise, smoking, sleep, cerebrovascular disease, frailty, atrial fibrillation and vitamin C). In contrast, two interventions are not recommended: oestrogen replacement therapy (Level A2) and acetylcholinesterase inhibitors (Level B).
Interpretation: Evidence-based suggestions are proposed, offering clinicians and stakeholders current guidance for the prevention of AD.