Blood and Cerebrospinal Fluid Autoantibody to Aβ Levels in Patients with Alzheimer's Disease: a Meta-Analysis Study.

Autoantibodies to beta amyloid (Aβ) have been suggested to be involved in the pathogenesis of Alzheimer's disease (AD). However, data from clinical studies were inconsistent on autoantibody to Aβ levels in patients with AD. Therefore, we systematically searched the literature and performed meta-analysis to summarize the data of autoantibodies to Aβ in AD patients. The systematic search from PubMed and Web of Science included thirty case-control studies with a total of 2901 individuals (1311 AD patients and 1590 healthy control subjects). Random-effect meta-analysis showed a significant increased endogenous IgG autoantibody to Aβ levels in blood when compared with controls (Hedges' g = 0.337, 95% CI = 0.020 to 0.654, P = 0.03). In contrast, blood IgM autoantibody to Aβ levels was significantly decreased in patients with AD relative to control subjects (Hedges' g = - 0.962, 95% CI = - 1.797 to - 0.126, P = 0.024). Furthermore, cerebrospinal fluid Aβ levels were not significantly different between AD patients and control subjects (Hedges' g = - 0.446, 95% CI = - 2.357 to 1.464, P = 0.647). Subgroup analysis revealed that detection method contributed to the heterogeneity for studies measuring blood IgG autoantibody to Aβ levels in AD patients. Meta-regression analyses suggested that sex is a confounder for the outcome of the meta-analysis. Taken together, the results of this meta-analysis clarified circulating autoantibodies to Aβ levels in AD patients and suggested that endogenous IgG and IgM-class antibodies to Aβ may play a role in the pathogenesis of AD.