“…Indeed, muscarinic receptors recently were demonstrated and characterized in murine lymphocytes {2, 14,191 and in peripheral circulating human blood lymphocytes 1343. As diminished function of central cholinergic systems has been implicated in the deterioration of mental faculties during aging 14, 9, 127 and as an etiological factor in senile dementia of the Alzheimer type (SDAT) [8, 10, 13,23, 25,27,29,32 J, a peripheral marker for central muscarinic cholinergic function would be very useful E27, 291. It was, therefore, of interest to determine whether any changes in muscarinic binding by peripheral lymphocytes occur during normal aging and in senile dementia.…”