Age-dependent phenotypic characteristics of a triple transgenic mouse model of Alzheimer disease

The triple-transgenic mouse line (3XTg-AD) harboring PS1(M146V), APP(SWe), and tau(p30IL) transgenes represents the only transgenic model for Alzheimer's disease (AD) to date capturing both beta-amyloid and tau neuropathology. The present study provides an extensive behavioral characterization of the 3XTg-AD mouse line, evaluating the emergence of noncognitive and cognitive AD-like symptoms at two ages corresponding to the early (6-7 months) and advanced (12-13 months) stages of AD-pathology. Enhanced responsiveness to aversive stimulation was detected in mutant mice at both ages: the 3XTg-AD genotype enhanced acoustic startle response and facilitated performance in the cued-version of the water maze. These noncognitive phenotypes were accompanied by hyperactivity and reduced locomotor habituation in the open field at the older age. Signs of cognitive aberrations were also detected at both ages, but they were limited to associative learning. The present study suggests that this popular transgenic mouse model of AD has clear phenotypes beyond the cognitive domain, and their potential relationship to the cognitive phenotypes should be further explored.