[Morphological changes in the human cerebral cortex in dementia]

Many diseases of the brain leading to impairment of intellectual capacities are associated with morphological changes in the anteromedial portions of the temporal lobe. Among these are Alzheimer's disease, Parkinson's disease and the syndrome of dementia with argyrophilic grains. The hallmarks of Alzheimer's disease are intraneuronal neurofibrillary changes and extracellular amyloid deposits. The neurofibrillary changes consist of neurofibrillary tangles, neuritic plaques and neuropil threads. The distribution pattern of neurofibrillary changes differs from the distribution of amyloid deposits. The neurofibrillary changes exhibit a distinct but varying distribution pattern in different areas of the cerebral cortex. In fully developed Alzheimer's disease, both the hippocampal formation and isocortical association areas are severely involved while the brunt of the pathology is found in the entorhinal region. The entorhinal region receives information from various isocortical association areas and limbic circuits and projects to the hippocampal formation via the perforant path. This fibre tract is mainly generated by projection neurons within the superficial entorhinal cell layer. In Alzheimer's disease virtually all projection neurons within this layer are destroyed by neurofibrillary tangles. In cases of Parkinson's disease with progressive cognitive decline the neurofibrillary changes are confined to the outer cellular layer of the entorhinal region. In cases of "dementia with argyrophilic grains" the argyrophilic grains are predominantly encountered in the hippocampal formation and in the outer layers of the entorhinal region.(ABSTRACT TRUNCATED AT 250 WORDS)