Environmental enrichment improves cognition in aged Alzheimer's transgenic mice despite stable beta-amyloid deposition.

Environmental enrichment (EE) has been shown to improve cognitive performance and brain indices of cognition in normal mice and rats. Because the therapeutic potential of intensive, long-term EE to benefit patients with Alzheimer's disease (AD) has yet to be explored, the present study evaluated the effect of long-term EE on cognition in an animal model of AD, the APPsw transgenic mouse. Beginning at 16 months of age, APPsw mice were put into EE or standard housing for 4 months and then tested in four cognitive-based tasks (Morris maze, circular platform, platform recognition, and radial arm water maze) between 20 and 22 months of age. Our results indicate that long-term EE of aged APPsw mice results in global, overall improvement in cognitive function across these tasks without decreasing brain beta-amyloid (A beta) deposition. The results suggest that long-term EE/cognitive stimulation could provide cognitive stabilization or improvement to AD patients through mechanisms independent of A beta deposition and clearance.