The effects of poverty and education on temporoparietal perfusion in Alzheimer's disease: A reconsideration of the cerebral reserve hypothesis

The cerebral reserve hypothesis proposes that education may provide extra brain reserve that allows an individual to cope longer before Alzheimer's disease (AD) is expressed clinically. Studies of temporoparietal (TP) blood perfusion have been used to support this hypothesis. We reconsider the reserve hypothesis by examining various models of the effects of poverty and its relationship to education on TP perfusion. Of 41 patients with 'probable' AD, 63% evidenced TP hypoperfusion with SPECT. When each variable was examined separately, persons with lower education (OR = 4.40, 95% CI 1.09-17.73, p = 0.04) and poverty (OR = 5.43, 95% CI 1.37-21.62, p = 0.02) were significantly less likely to have TP hypoperfusion. However, neither variable had independent effects when tested simultaneously. Neither additive (poverty + education) nor interactive (poverty x education) explanatory models of TP hypoperfusion had any additional significant explanatory power. The findings suggest that the conclusion that higher education provides a protective effect in AD may be premature, and that there is equally compelling evidence that lower education and/or poverty may diminish cerebral reserve.