Figure 1.

Schematic representing three potential classes of mechanisms linking cognitive and social lifestyle factors with neuropathology and dementia. Lifestyle I is a direct disease effect on neuropathology such that it is directly associated with more or less pathology. Lifestyle II represents a modulatory effect such that the experiential factor alters the relation of pathology to cognition, i.e., increases or decreases the probability of dementia for any given level of neuropathology. Lifestyle III represents a pathway linking lifestyle to dementia that is unrelated to classic neuropathology.