[Role of the involvement of the reticular formation in the dementia of Parkinson's disease].

A post mortem study of 14 cases of Parkinson's disease was reported. Seven patients were mentally deteriorated and 7 were not, retrospectively. The semiquantitative study of the cortical lesions of senile dementia of Alzheimer type did not show any recognizable difference between the 2 groups. A greater degree of neuronal cell loss in the nucleus basalis of Meynert in the mentally deteriorated group was confirmed. The incidence of Lewy bodies in the brain stem reticular formation was remarkably increased in the mentally deteriorated group. A study of the reticular formation, including the raphe nuclei and the magnocellular nuclei of mid pons and upper medulla, revealed a significant higher incidence of Lewy bodies throughout the whole reticular formation in the mentally deteriorated group. The possible role of the lesions of the ascending reticular activating system in the mental deterioration is discussed.