Neuropathologic Changes of the Temporal Pole in Alzheimer's Disease and Pick's Disease

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Abstract
Objective: To describe the pattern of neuropathologic changes in temporal polar cortex in Alzheimer's disease (AD) in comparison with changes in Pick's disease (PD) and normal elderly cytoarchitecture. Design: Examination of degenerative changes, neurofibrillary tangles, and senile plaques in the temporal poles of 10 patients with AD, three patients with PD, and five age-compatible control subjects, by means of thionin and thioflavine S stains and Alz-50 and ubiquitin immunocytochemistry. Subjects: All patients had a documented history of dementia and AD or PD confirmed on neuropathologic examination. Control subjects were without a history of cognitive impairment or evident neuropathologic changes. Outcome Measures: Cytoarchitecture, neuronal loss, neurofibrillary tangles, senile plaques, and Pick bodies. Results: All patients with AD showed atrophy of the temporal pole and marked neuronal loss, especially in layers III and V and, to a lesser degree, in layers II and VI. Heavy accumulation of neurofibrillary tangles was found in layers II, III, V, and VI. Patients with PD showed extensive neuron loss throughout, although this appeared to be most prominent in layer III. Conclusions: Both AD and PD pathologic changes severely affect the layers of the temporal pole that mediate widespread reciprocal connections with temporal and frontal cortices and limbic cortical and subcortical structures. Neural systems that interconnect temporal polar cortex with sensory association areas and memoryrelated limbic structures are, therefore, disrupted, and it is likely that these lesions play a role in the multifaceted cognitive and behavioral changes of AD and PD.