The effect of beta adrenergic blocking drugs on speakers' performance and memory

Propranolol 40 mg was compared with a matched placebo tablet in its effect on the performance of anxious and non-anxious human volunteers. Subjects were required to give a brief speech, which was video-taped and later rated by trained observers for signs of anxiety; propranolol clearly reduced rated anxiety in the non-verbal behaviour of anxious subjects, as well as the anxiety observed in the speech of the anxious compared to the non-anxious. It also affected self-reported anxiety in the anxious, and reduced the pulse rate of anxious and non-anxious alike. Subjects were also prompted, by being given the first letter, to recall both difficult and easy words, drawn from selected verbal categories; propranolol impaired recall of difficult items in the memory of anxious subjects. Results were interpreted as showing a central as well as peripheral role for propranolol in blocking adrenergic receptors' activity in anxiety.