MAPT and Alzheimer disease: Here, in a mouse model of AD, at a stage when no Aβ-plaque deposition, hyperphosphorylated tau tangles or any sign of neuronal loss in cortical and hippocampal regions involved in memory deficits has yet occurred21, 23, 24, we provide evidence that a specific apoptotic process is taking place in the VTA, causing a progressive degeneration of the DAergic neuronal population.