Adiponectin as a biomarker in dementia: A systematic review and meta‐analysis

Abstract

AbstractBackgroundAlzheimer disease (AD) and Vascular dementia (VaD) are the most common causes of dementia. At mild stages, clinical differentiation is frequently not possible, creating the requirement of complex laboratory test and imaging technique that may not be available worldwide. Therefore, more practical, and effective biomarkers are need. Serum adiponectin is a modulating hormone of vasculature structure and function. Altered serum adiponectin levels had been reported in patients with AD and VaD compared to controls. To determine if serum adiponectin levels could be used to differentiate between AD and VaD, we conducted a systematic review and meta‐analysis.MethodA systematic review following PRISMA guidelines was conducted. The search strategy included terms related to dementia and adiponectin and was conducted in 4 databases (MEDLINE, Ovid, Scopus, and EMBASE) up until April 2021. The studies were screened by 2 authors in a two‐step approach. Original studies comparing serum adiponectin between AD and VaD patients were included. Risk of bias was assessed using QUADAS. In the meta‐analysis, we compared the mean difference values of adiponectin between AD and VaD patients.ResultA total of 917 studies were screened. After applying eligibility criteria, 72 studies were fully screened, and 3 articles were reviewed and included in the meta‐analysis. A total of 454 patients with AD and 148 with VaD were analyzed. Although patients with AD have slightly higher mean adiponectin values than VaD patients, there were no statistically significant differences (mean difference, 1.61, 95% CI ‐0.61 to 3.84; P=0.16, I2 =96%) (Fig. 1). The main risk of bias concerns was the retrospective study design in most of the studies, the heterogeneity in dementia diagnosis, and the lack of report and consideration of factors that could alter adiponectin.ConclusionThere was no difference in the serum adiponectin levels between patients with AD and VaD. Nevertheless, factors that could alter serum adiponectin such as metabolic comorbidities (e.g., hypertension, type 2 diabetes, cardiovascular disease), weight and medicaments were not considered when comparing adiponectin levels between AD and VaD patients. Hence, further studies should account and adjust for these factors when comparing serum adiponectin in different types of dementia.