Changes of muscarinic cholinergic binding by lymphocytes in Parkinson's disease with and without dementia.

We compared the muscarinic cholinergic binding in lymphocytes of 44 patients with idiopathic Parkinson's disease with 23 age-matched normal volunteers, using [3H]quinuclidinyl benzilate. In 24 patients with Parkinson's disease without dementia, binding was normal in 12, below control values in 6, whereas the remaining 6 (all on anticholinergic medication) showed very high binding. In all 20 patients with Parkinson's disease and with dementia, the binding was below control levels, indicating that in these patients, as in patients with Alzheimer's dementia, the cholinergic muscarinic binding by lymphocytes is reduced.