THE RELATIONSHIP BETWEEN DEMENTIA AND DIRECT INVOLVEMENT OF THE HIPPOCAMPUS AND AMYGDALA IN PARKINSONS-DISEASE

Severe dementia affects 10 to 20% of all patients with Parkinson's dis ease (PD) and is particularly common in those aged 65 years and over. In a clinicopathologic study, we correlated Mini-Mental State Examinat ion scores and DSM-III dementia ratings with the density of Lewy bodie s, Lewy neurites, neurofibrillary tangles, neuritic plaques, gliosis, and neurons in the hippocampus and amygdala of 27 PD patients without Alzheimer's disease changes. Cortical Lewy body densities were examine d in the anterior cingulate gyrus. The degree of cognitive impairment was correlated with the density of Lewy neurites in the CA2 hippocampa l field, raising the possibility that disruption of the connection bet ween the dentate gyrus, entorhinal cortex, septal nuclei, and hypothal amus and the CA1 field contributes to dementia in PD.