The association of genes such as brain-derived neurotrophic factor (BDNF) and apolipoprotein-E (ApoE) with cognitive decline and late-onset Alzheimer’s disease (AD) has been investigated (e.g., Corder et al., 1993; Slooter et al., 1998; Hariri et al., 2003; Cosentino et al., 2008). Here, BDNF is linked to early-onset autosomal dominant Alzheimer disease.