Organic Mental Syndrome in Parkinson's Disease

To the Editor.—  I was surprised at the low incidence (15% ) of organic mental syndrome (OMS) in "typical" parkinsonism patients as described in the article "Organic Mental Syndrome and Confusional States in Parkinson's Disease" by Sroka et al (Archives 1981;38:339-342). In the study by Celesia and Wanamaker,¹ 40% of patients with idiopathic Parkinson's disease were found to be demented. Lieberman et al² reported that 32% of 520 patients with Parkinson's disease had moderate to severe dementia. In the study by Boller et al,³ 42% of patients with Parkinson's disease proved at autopsy had senile plaques and fibrillary tangles in the cerebral cortex. In my own small series (unpublished data, October 1978 to August 1981), I have found 45% of "typical" parkinsonism patients to have OMS.The subjects in my study included 22 patients with idiopathic Parkinson's disease ("typical" parkinsonism) and seven patients with other syndromes ("atypical" parkinsonism).