the speed factor were implicated in the pathophysiology of AD. Several genes (e.g., APOE, APP) predisposing to AD have been associated with variation in normal cognition, and there is some indication that the effect of these genes may be stronger for processing speed than for general intelligence or even memory (Harris et al., 2007; Luciano et al., 2009). Thus, the pursuit of AD genes in normal cognition, and especially processing speed traits, might prove worthwhile.
