CD27 and Alzheimer disease: 2019), their negative association with cognitive function in our study presents an unexpected paradox. Our observations regarding IgD− CD27− B cells also diverge from existing evidence. Previous investigations have documented elevated Double Negative (IgG+IgD−CD27−) B cells in Alzheimer's disease patients, exhibiting inflammatory receptor characteristics (Bulati et al. 2015; Martorana et al. 2014). Additionally, research has shown that CD27− IgD− B cell populations exert inflammatory effects in elderly Chinese males, correlating with functional deterioration (Nevalainen et al. 2019).