IL15 and early-onset autosomal dominant Alzheimer disease: While analyses of plasma levels of IL-15 in individuals with Alzheimer’s disease are limited, a smaller study of 20 subjects with Alzheimer’s disease compared to 15 controls reports that IL-15 is slightly but significantly reduced in the plasma of individuals with Alzheimer’s disease50; another study of 52 subjects with Alzheimer’s disease compared to 18 controls found no difference in IL-15 in CSF or plasma51.