Comparison of amyloid and tau pathology in the small and large intestines of individuals with Alzheimer's disease, Parkinson's disease, and Dementia with Lewy bodies.

Alzheimer's disease (AD) brains are characterized by accumulations of neurofibrillary tangles and amyloid β (Aβ) plaques. Since enteric neurons express tau and the amyloid precursor protein (APP), we asked whether neurofibrillary tangles and Aβ aggregates were present in AD intestines compared to healthy controls and individuals with Parkinson's disease (PD) and Dementia with Lewy Bodies (DLB). Neuron-like APP and Aβ immunoreactivities were observed in all groups with no observable plaques. No tangle-like structures were observed in any group although p-Ser 396/404 tau immunoreactivity was seen. The enteric nervous system appears to be protected from developing tangle and plaque pathology in AD.