Pathological alterations in the amygdala in Alzheimer's disease.

The amygdala is severely and consistently affected by pathology in Alzheimer's disease. The distribution of Thioflavin S-stained neurofibrillary tangles and neuritic plaques was examined in the various nuclei that form the amygdala in 20 cases of clinically diagnosed Alzheimer's disease and five non-demented control cases. Large numbers of neurofibrillary tangles and neuritic plaques were observed in the accessory basal and cortical nuclei and the cortical transition area, while there was lesser involvement of the mediobasal nucleus. The medial, lateral, laterobasal and central nuclei were relatively spared. The distribution of neurofibrillary tangles and neuritic plaques was compared with neuroanatomic connections known from non-human primate experimental studies. This comparison suggests that (1) nuclei receiving and giving rise to hippocampal projections are consistently affected by neuropathological alterations in Alzheimer's disease; (2) the nuclei which receive strong cholinergic projections from the nucleus basalis of Meynert (e.g. laterobasal nucleus) have, in general, relatively few neuritic plaques; and (3) nuclei which receive olfactory projections are not uniformly affected, the cortical nucleus being heavily affected but the medial nucleus consistently spared.