ABSTRACT
The basis for cognitive reserve (CR) arose from the observation that the severity of neuropathological manisfestations of Alzheimer's disease (AD) did not always correlate well with severity of AD (Katzman et al., 1988). This observation led several investigators to propose the concept of CR (Katzman, 1993; Satz, 1993; Stern, Alexander, Prohovnik, & Mayeux, 1992; Stern et al., 1994). They argue that individuals develop cognitive reserve in the presence of favorable environments such as high educational level or by genetic predisposition, or both, and that CR increases the threshold for neuropsychological responses to brain insult. Those with a greater brain reserve capacity have a higher threshold for brain insult before clinical deficit appears. The concept of CR is evolving to include broader phenomena. Others have argued that more efficient circuitry is less likely to be disrupted and more resilient in the event of brain insult (Grady et al., 1996; Grasby et al., 1994). Stern (2002) applies CR to any situation where there is variation in response to brain injury, suggesting that CR can be applied to individuals who are healthy as well as those who are suffering from neurodegeneration.
