Studies investigating alterations of the endocannabinoid system (ECS) in Alzheimer’s disease (AD) in humans have reported inconsistent findings so far. We performed a systematic review of studies examining alterations of the ECS specifically within humans with AD or mild cognitive impairment (MCI), including neuroimaging studies, studies of serum and cerebrospinal fluid biomarkers, and post-mortem studies. We attempted to identify reported changes in the expression and activity of: cannabinoid receptors 1 and 2; anandamide (AEA); 2-arachidonoylglycerol (2-AG); monoacylglycerol lipase (MAGL); fatty acid amide hydrolase (FAAH); and transient receptor potential cation channel V1 (TRPV1). Twenty-two studies were identified for inclusion. Mixed findings were reported for most aspects of the ECS in AD, making it difficult to identify a particular profile of ECS alterations characterising AD. The included studies tended to be small, methodologically heterogeneous, and frequently did not control for important potential confounders, such as pathological progression of AD. Eight studies correlated ECS alterations with neuropsychometric performance measures, though studies infrequently examined behavioural and neuropsychiatric correlates.

PROSPERO database identifier: CRD42018096249.

迄今为止，关于人类阿尔茨海默病 (AD) 内源性大麻素系统 (ECS) 改变的研究报告了不一致的结果。我们对专门针对 AD 或轻度认知障碍 (MCI) 的人的 ECS 改变进行了系统评价，包括神经影像学研究、血清和脑脊液生物标志物研究以及尸检研究。我们试图确定报告的表达和活性变化： 大麻素受体 1 和 2；花生四烯酸（AEA）；2-花生四烯酰甘油（2-AG）；单酰基甘油脂肪酶（MAGL）；脂肪酸酰胺水解酶（FAAH）；和瞬时受体电位阳离子通道 V1 (TRPV1)。22 项研究被确定纳入。AD 中 ECS 的大多数方面报告的结果不一，使得难以识别表征 AD 的 ECS 改变的特定特征。纳入的研究往往规模较小，方法学上具有异质性，并且经常没有控制重要的潜在混杂因素，例如 AD 的病理进展。八项研究将 ECS 改变与神经心理表现测量相关联，尽管研究很少检查行为和神经精神病学的相关性。

PROSPERO 数据库标识符：CRD42018096249。