We examined the effects of non‐steroidal anti‐inflammatory drugs on cognitive decline as a function of phase of pre‐clinical Alzheimer disease.

Given recent findings that cognitive decline accelerates as clinical diagnosis is approached, we used rate of decline as a proxy for phase of pre‐clinical Alzheimer disease. We fit growth mixture models of Modified Mini‐Mental State (3MS) Examination trajectories with data from 2388 participants in the Alzheimer's Disease Anti‐inflammatory Prevention Trial and included class‐specific effects of naproxen and celecoxib.

We identified three classes: “no decline”, “slow decline”, and “fast decline”, and examined the effects of celecoxib and naproxen on linear slope and rate of change by class. Inclusion of quadratic terms improved fit of the model (−2 log likelihood difference: 369.23; p < 0.001) but resulted in reversal of effects over time. Over 4 years, participants in the slow‐decline class on placebo typically lost 6.6 3MS points, whereas those on naproxen lost 3.1 points (p‐value for difference: 0.19). Participants in the fast‐decline class on placebo typically lost 11.2 points, but those on celecoxib first declined and then gained points (p‐value for difference from placebo: 0.04), whereas those on naproxen showed a typical decline of 24.9 points (p‐value for difference from placebo: <0.0001).

Our results appeared statistically robust but provided some unexpected contrasts in effects of different treatments at different times. Naproxen may attenuate cognitive decline in slow decliners while accelerating decline in fast decliners. Celecoxib appeared to have similar effects at first but then attenuated change in fast decliners. Copyright © 2011 John Wiley & Sons, Ltd.