Extrapyramidal signs in Alzheimer's disease.

The occurrence and type of extrapyramidal signs were investigated in 143 patients with dementia of the Alzheimer type. Only 8% of the patients were free of extrapyramidal signs. The most common type of extrapyramidal involvement was a rigid, hypokinetic, and hypomimic pattern. Resting tremor was rarely encountered. Dyskinetic signs, mostly orofacial, were seen in 17%. These observations suggest that in most patients with advanced Alzheimer's disease, there is a striatal dopaminergic hypofunction, appearing clinically as hypokinesia and rigidity. However, some patients exhibit predominantly dyskinetic signs, implying more complex basal ganglia dysfunction.