Supersensitive muscarinic cholinergic receptors may underlie mood, neuroendocrine & sleep disturbances in depression. In this study muscarinic binding sites in the brains of suicides & controls were examined in matched pair design using the radioligand QNB & focusing on regions of the brain mediating those functions. Receptor densities & binding affinities did not differ between subjects & controls but there was a trend for both to be lower in suicides. (NBB)