Region-specific age at onset of beta-amyloid in dogs.

Cortical patterns of beta-amyloid (Abeta) deposition were evaluated in 40 beagle dogs ranging in age from 2 to 18 years. Abeta deposition in the prefrontal, occipital, parietal and entorhinal cortices was visualized by using an antibody against Abeta1-42. A logistic regression was used to estimate differences in age-at-onset and rate of deposition of Abeta as a function of brain region. The earliest and most consistent site of Abeta deposition with age was in the prefrontal cortex. Entorhinal Abeta deposition was not consistently observed until the age of 14 years, but was present in a subset of dogs under the age of 14 years. These regional vulnerabilities to Abeta accumulation are similar to those seen in the aging human. By using parameters derived from regression analyses, it may be possible to predict the presence of Abeta within specific brain regions in individual dogs. We propose that these models will be a useful tool to evaluate interventions that delay the age of onset or slow the rate of accumulation of Abeta in the dog.