Non-Alzheimer's dementia due to lobar atrophy had choline acetyltransferase activities comparable with control rather than Alzheimer's disease values, based on 3 autopsy proven cases on Pick's disease and biopsies from 3 examples of dementia of frontal lobe type. Muscarinic cholinergic receptors were relatively spared only in Alzheimer's disease. Serotonin receptors were markedly reduced (based on Pick cases) whereas measures that reflected presynaptic serotonergic activity were either not affected or increased. Cerebrospinal fluid and brain tissue measurements suggested that inhibitory interneurones and dopamine release were relatively spared. There was no in vitro evidence of hypometabolism.