Interest in physiology/cognition relations is increasing, in step with the realization that the individual ages as a whole, adaptive, living system. If a physiological system declines, a person's cognitive abilities may be reduced, unless some compensatory mechanism operates. Understanding this set of relationships permits potential interventions. This study explored the influences of blood
... [Show full abstract] pressure on memory for designs and Wechsler Adult Intelligence Scale vocabulary performance in terms of seven theoretical models which test not only for linear effects but for effects having a more complex, nonlinear time-lagged form as well. Each of a large number of hypotheses was tested twice, first with systolic, then with diastolic pressure variables. The 25-year data base of the Baltimore Longitudinal Study of Aging was used. Significant complex relationships between blood pressure and cognition were found. The theory that best fits results of this study is that optimal pressure delivers optimal oxygen to the brain, and optimal pressure depends on the state of the whole system, maintained and adjusted by age related feedback loops connected to both blood pressure and cognitive adaptive systems. The use of nonlinear, lagged multivariate models is recommended, since these hypotheses received support. (Author/ABL)