Cognitive Reserve - Clinical Implications

Clinical Implications

The clinical diagnosis of dementia is not perfectly linked to levels of underlying neuropathology. The theory of cognitive reserve explains this phenomenon. People with high reserve go undiagnosed until damage is severe, then rapid decline ensues.

Cognitive reserve can be estimated clinically as it is effectively general cognitive ability and knowledge. The variables that are associated with cognitive reserve include: IQ, brain size, education, professional attainment, leisure activities, and familial history (of diagnosed dementia).

It is important to note that cognitive reserve (and the variables associated with it) do not "protect" from Alzheimer's disease as a disease process—the definition of cognitive reserve is based exactly on the presence of disease pathology. This means that the traditional idea that education protects from Alzhemier's disease is false, albeit it cognitive reserve is protective of the clinical manifestations of disease.

The presence of cognitive reserve implies that people with greater reserve who already are suffering neuropathological changes in the brain will not be picked up by standard clinical cognitive testing. Conversely anyone who has used these instruments clinically knows that they can yield false positives in people with very low reserve. From this point of view the concept of "adequate level of challenge" easily emerges. Conceivably one could measure cognitive reserve and then offer specifically tailored tests that would pose enough level of challenge to accurately detect early cognitive impairment both in individuals with high and low reserve. This has implications for treatment and care. Currently some people who would be eligible for it are not offered treatment while it may be offered in other cases needlessly.

In people with high reserve deterioration occurs rapidly once the threshold is reached. In these individuals and their carers early diagnosis might provide an opportunity to plan future care and to adjust to the diagnosis while they are still able to make decisions.