Ic-p3-176 What Goes Up, Must Come Down: Compensatory Neural Activity among the Very Old

Background: Understanding factors that contribute to successful cognitive aging has become increasingly important as a growing portion of the population lives to very old age. Our research has focused on different patterns of cognitive aging by using electrophysiologic and behavioral measures. Previously, we demonstrated (e.g., NeuroImage, 2008; 39(1)) that cognitively high-functioning younger-old (y-old) (65-79 y.o.) subjects allocate more neural resources, as measured by the P3 event-related po­ tential, than cognitively high-functioning middle-aged and young subjects and than cognitively average-functioning y-old subjects. Interestingly, al­ though cognitively average-functioning middle-aged subjects appropriate more resources to novel stimuli than cognitively-matched young subjects, cognitively average-functioning y-old subjects exhibit a substantial reduc­ tion in novelty P3 amplitude. These findings suggest that age-related compensatory activity may involve increased allocation of capacity-limited controlled resources that persists until capacity limits are exceeded. For cognitively average-functioning adults this may occur by y-old age. We hypothesized that in cognitively high functioning adults this would develop in old-old (o-old) age. Here we have extended our investigations to include o-old individuals (’80 y.o.), and report on preliminary results. Objective: To determine whether cognitively high functioning o-old adults continue to exhibit compensatory neural activity and a preference for attending to novelty. Methods: Electrophysiologic and behavioral responses to stan­ dard, target, and novel visual stimuli were recorded while young, middleaged, y-old, and o-old individuals performed a subject-controlled variant of the novelty oddball task. Results: Cognitively high-functioning o-old adults exhibited a large reduction in their novelty P3, but not until their mid to late 80s. Behaviorally, cognitively high-functioning individuals in their 90s continued to spend more time exploring novel than repetitive standard visual stimuli. Conclusions: Our research suggests that age-related com­ pensatory neural activity may not be limited to high-functioning older individuals with substantial cognitive reserve, but also be observed among cognitively average-functioning adults at an earlier stage of the lifespan. Cognitively high-functioning adults appear to have the capacity to appro­ priate compensatory neural resources at least through their early 80s, and continue to be attracted to novelty, a hallmark of healthy human behavior, at least through their early 90s.