Some immunohistochemical features of argyrophilic grain dementia with normal cortical choline acetyltransferase levels but extensive subcortical pathology and markedly reduced dopamine.

Detailed immunohistochemical and biochemical studies are reported on two cases of progressive dementia showing no Alzheimer-type pathology but extensive argyrophilic grains as described previously by Braak and Braak. These cases had no specific clinical features, and the pathology of these brains showed subcortical gliosis (proliferation of astrocytes and microglia) without significant neuronal losses. Interesting novel immunohistochemical findings were the profuse appearance of complement-activated oligodendrocytes and oligodendroglial microtubular masses. Their appearance seems to indicate oligodendroglial reactions to widespread damage of myelinated axons. Cortical levels of choline acetyltransferase were normal, but striatal levels of dopamine and its metabolites were markedly reduced. This disease may be consistent with the criteria for progressive subcortical gliosis.