APP and attention deficit-hyperactivity disorder: However, the models also seem to present with features that do not reflect the natural course of AD and ADHD in humans, e.g., Tg2576 animals -fAD model, overexpress a mutant form of APP with a Swedish mutation (KM670/671NL) throughout their life (representing at best ∼1% of familial AD cases) and do not show signs of neuronal loss and neurofibrillary tangles (Irizarry et al., 1997).