Fig. 3.

Three possible models of the effects of brain reserve (BR) on clinical progression. a The “threshold model”: accumulation of pathology initially has no clinical effect in individuals with higher BR, and only results in cognitive decline after a certain inflection point. b The “initial advantage model”: higher BR is associated with a higher premorbid level of cognitive function, and thus more cognitive decline is needed before an objective level of cognitive impairment is reached. c The “lower workload model”: higher BR places less workload on individual neurons, and thus the loss of structure leads to relatively little cognitive decline