The neuropathologic basis of different clinical subgroups of Parkinson's disease

Clinical and neuropathologic data in 45 patients with Parkinson's disease (PD) were compared. Twenty-seven patients suffered from marked akinesia and rigidity (AR-type) and 18 patients from predominant resting tremor (T-type). Dementia, depression, and psychosis occurred in 26, 18, and 18 patients, respectively. Neuronal counts were performed in defined areas of the medial and lateral substantia nigra (SNM, SNL), locus ceruleus (LC), and dorsal raphe nucleus (DRN). The AR-type (compared with the T-type) showed higher neuronal loss of LC, SNL, SNM, and more severe gliosis, extraneuronal melanin deposits, and neuroaxonal dystrophy in substantia nigra. Demented PD patients showed more intense cortical Alzheimer lesions and higher neuronal depletion in the SNM, whereas PD subjects with moderate or marked dementia differed from mildly or not demented ones only in the higher degree of cortical Alzheimer lesions. More severe neuronal cell loss of DRN was observed in PD patients with depression. Occurrence of psychosis was not associated with any pathologic feature. Our findings indicate that some major clinical features of PD are related to distinct neuropathologic lesions.