In a two-year study of aging canines, researchers at the University of California, Irvine, suggest that treating the predominant pathology of Alzheimer's disease -- beta-amyloid plaques -- by itself may have only limited clinical benefit.

The study, published in the Journal of Neuroscience, said that after the aged dogs with beta-amyloid-plaque growth were immunized -- similar to starting a treatment in patients with Alzheimer's disease -- found, in comparison with non-treated aged dogs, little difference in the results of behavioral tests that measure cognitive loss.

Later, brain autopsies showed that although plaques had been cleared from multiple brain regions damaged neurons remained.

Study leader Elizabeth Head said the finding implies that after clearing beta-amyloid plaques from the brain, the next step is to repair the damaged neurons.