CD40 has an important role in neuroinflammatory diseases and abnormal expression of CD40 and its ligand CD154 has been shown in Alzheimer's disease (Calingasan et al., 2002; Giunta et al., 2010), multiple sclerosis (Gerritse et al., 1996), and HIV-1 associated dementia (D'Aversa et al., 2002). Here, CD40 is linked to early-onset autosomal dominant Alzheimer disease.