These substances include reactive oxygen species and inflammatory cytokines such as IL-1β, TNF-α, and IL-6.[26] Thomsen reported significant perivascular macrophage infiltration in the cortex white matter of canine cognitive dysfunction (CCD) animal models, suggesting a role in pathology that might parallel changes observed in early Alzheimer’s disease in humans. Here, IL6 is linked to early-onset autosomal dominant Alzheimer disease.