Brain muscarinic receptors in senile dementia

Muscarinic receptors were analyzed in various post-mortem brain samples of 39 patients with different types of dementia and of 30 age-matched controls by the specific binding of [3H]QNB. The diagnoses were verified neuropathologically. The binding of [3H]QNB was significantly decreased in the hippocampus, amygdala and nucleus accumbens in patients with Alzheimer's disease (AD) and with combined type of dementia (CD), whereas in patients with multi-infarct dementia (MID) the binding was not significantly decreased in the limbic areas but only in the caudate nucleus. Of the clinical variables, orofacial dyskinesias in patients with AD but not with MID correlated with low brain weight and with the decreased [3H]QNB binding in the striatum and frontal cortex. The results reveal some differences between AD and MID. Changes in muscarinic receptor binding show that the cholinergic neurons in the limbic system are especially vulnerable in patients with AD and CD.