[en] Nicotinic cholinergic receptors were measured in human frontal cortex using (³H)nicotine and (³H)acetylcholine (in the presence of atropine) as receptor ligands. A parallel marked reduction in number of (³H)nicotine (52%, P<0.01) and (³H)acetylcholine (-55%, P<0.05) binding was found in the frontal cortex of Alzheimer brains (AD/SDAT) when compared to age-matched control brains. As a comparison the number of muscarinic receptors was quantified using (³H)quinuclidinyl benzilate and found to be significantly increased (+23%, P<0.01) in AD/SDAT compared to controls. (author)