Clinical and neuropathological findings in a patient with familial Alzheimer disease showing a mutation in the PSEN1 gene

Over 100 mutations have been described in the presenilin-1 gene (PSEN1), resulting in familial Alzheimer disease (AD). However, of the limited number of autopsy cases, only one has been reported from an AD family with an L420R PSEN1 mutation. We describe here clinical and neuropathological features of a patient with dementia-parkinsonism from a family with a PSEN1 mutation (L420R). A 43-year-old Japanese woman was autopsied 12 years after the onset of her progressive dementia and 4 years after the onset of parkinsonism. Throughout the neocortex and hippocampus, cotton wool plaques were identified, densely packed, in almost all the cortical layers along with neuronal loss, gliosis, NFT and neuropil threads. In addition, CAA affecting meningeal, subpial and cortical arterioles was found, as well as amyloid β-protein (Aβ)-deposition in the capillaries (capillary CAA) in the neocortex and subcortical nuclei. There was loss of pigmented neurons in the substantia nigra. The putamen was densely packed with diffuse plaques and rarely showed capillary CAA, whereas the globus pallidus showed extensive capillary CAA but no plaques. This differential distribution is similar to that reported for a previous patient with a mutation in PSEN1. It is concluded that neuropathological changes in the substantia nigra and lenticular nuclei were responsible for the patient's parkinsonism. Capillary transport of Aβ unique to the respective tissue of the patient may result in the differential distribution of Aβ between the putamen and globus pallidus seen in individuals with a PSEN1 mutation.