Clinical records and neuropathological specimens from 36 patients with autopsy-demonstrated idiopathic Parkinson disease (PD) were reviewed independently and the results compared. Nine (31%) of the 29 patients with adequate clinical data had severe dementia and 7 (24%) had mild dementia. The cerebral cortex showed senile plaques and fibrillary tangles in 15 of the 36 patients (42%). These changes were found in all 9 patients with severe dementia, in 3 of the 7 with mild dementia, and in 3 of the 13 patients with normal mental status. The prevalence of pathologically established Alzheimer changes and dementia among the patients with PD (33%) was over six times that found in an age-matched population (5.1%). Survival after the onset of PD with Alzheimer disease was shorter than in PD without Alzheimer disease.

Fourteen cases of ganglioglioma are analyzed. This tumor can be found anywhere within the central nervous system. The histological appearance is highly variable and does not relate to the biological behavior. The prognosis depends on the location and possible modes of treatment. Overall, the lesion appears to be nonaggressive and consistent with long survival.

A mitochondrial defect was investigated in an infant with fatal congenital lactic acidosis (3-14 mM), high lactate-to-pyruvate ratio, hypotonia, and cardiomyopathy. His sister had died with a similar disorder. Resting oxygen consumption was 150% of controls. Pathological findings included increased numbers of skeletal muscle mitochondria (many with proliferated, concentric cristae), cardiomegaly, fatty infiltration of the viscera, and spongy encephalopathy. Mitochondria from liver and muscle biopsies oxidized NADH-linked substrates at rates 20-50% of controls, whereas succinate oxidation by muscle mitochondria was increased. Mitochondrial NADH dehydrogenase activity (complex I, assayed as rotenone-sensitive NADH oxidase, NADH-duroquinone reductase, and NADH-cytochrome c reductase) was 0-10% of controls, and NADH-ferricyanide reductase activity was 25-50% of controls in the mitochondria and in skin fibroblasts. Activities of other electron transport complexes and related enzymes were normal. Familial deficiency of a component of mitochondrial NADH dehydrogenase (complex I) proximal to the rotenone-sensitive site thus accounts for this disorder.

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