PATHOLOGICAL CORRELATES OF EXTRAPYRAMIDAL SIGNS IN ALZHEIMERS-DISEASE

Extrapyramidal signs frequently accompany Alzheimer's disease (AD), bu t the pathological substrate remains unknown. Clinical and postmortem information from patients with AD, Parkinson's disease, or progressive supranuclear palsy and control subjects seen at a large tertiary medi cal center between 1989 and 1994 was examined. AD patients who had tak en neuroleptics and AD brains that also contained Lewy bodies were exc luded. The presence of extrapyramidal signs was determined using the U nified Parkinson's Disease Rating Scale. Sections of basal ganglia, su bthalamic nucleus, and substantia nigra were examined for neurofibrill ary tangles and neuropil threads and the nigra for neuronal numbers. P atients with AD (with or without extrapyramidal signs) did not show ne uronal loss in the nigra compared to control subjects, while both Park inson's disease and progressive supranuclear palsy brains showed marke d depletion. The number of neurofibrillary tangles and neuropil thread s was increased in AD (with or without extrapyramidal signs) nigra com pared to control tissue, and also in progressive supranuclear palsy ni gra, but not Parkinson's disease nigra. The numbers of nigral neurofib rillary tangles and neuropil threads were positively related to extrap yramidal signs in AD. There were no correlations between tangles and t hreads in the basal ganglia or subthalamic nucleus and extrapyramidal signs in AD. Thus, extrapyramidal signs in AD correlate best with tang le pathology in the nigra and do not require the concomitant presence of Lewy bodies.