Argyrophilic grains: characteristic pathology of cerebral cortex in cases of adult onset dementia without Alzheimer changes.

Brains from 56 individuals suffering from adult onset dementia and devoid of macroscopically detectable infarctions were examined. Forty brains showed the characteristic cytoskeleton changes of Alzheimer's disease. Eight brains failed to reveal considerable numbers of neuritic plaques, neurofibrillary tangles, and neuropil threads, but these brains showed the presence of abnormal and intensely argyrophilic grains loosely scattered throughout the neuropil. Abundant numbers of these small spindle-shaped grains were encountered within the pyramidal layers of CA1 and layer Pre-beta of the entorhinal region. Eight brains showed both the argyrophilic grains and the neurofibrillary changes of the Alzheimer type. The appearance of argyrophilic grains within the neuropil is considered a morphological substrate of an unknown disease associated with adult onset dementia.