The effects of anticholinergics on the photopalpebral reflex, memory and mood

This study investigated central anticholinergic drug effects on: (1) the Randt Memory Test, a relatively new instrument which measures the acquisition and recall of verbal and pictorial information; (2) the averaged photopalpebral reflex (PPR), an electrophysiological parameter, the validity of which needs to be further investigated in pharmacological research and; (3) mood as measured by a 16-item visual analogue scale. Atropine (1 mg and 2 mg), pirenzepine (20 mg) and a placebo were administered intramuscularly in a double-blind cross-over trial in eight healthy volunteers. There were no inter-treatment differences on the Randt Memory Test. This finding is seemingly in contrast to those reported by some authors using other memory tests. In contrast to the reported effects of some benzodiazepines, the anticholinergics used in the present study did not prolong the latencies of the PPR, but reduced the amplitudes. Visual analogue scales indicated central effects for both pirenzepine and atropine. This implies pirenzepine's penetration of the blood-brain barrier and a physiological function for central muscarinic-1-receptors. The significant anticholinergic effects were exclusive to the "alertness" factor.