The canine (dog) model of human aging and disease: dietary, environmental and immunotherapy approaches.

Aged dogs (beagles) develop losses in executive function, learning and memory. The severity of decline in these cognitive domains represents a spectrum that captures normal aging, mild cognitive impairment and early/mild Alzheimer's disease (AD) in humans. In parallel, dogs naturally accumulate several types of neuropathology (although not all) consistent with human brain aging and AD including cortical atrophy, neuron loss, loss of neurogenesis, amyloid-beta (Abeta) plaques, cerebral amyloid angiopathy and oxidative damage. Many of these neuropathological features correlate with the extent of cognitive decline in a brain region-dependent manner. Dogs are ideally suited for longitudinal studies, and we provide a summary of the beneficial effects of an antioxidant diet, behavioral enrichment, and Abeta immunotherapy. In addition, combinatorial treatment approaches can be a powerful strategy for improving brain function through enhancement of multiple molecular pathways.