A comparison of some physiological and psychological effects of propranolol and diazepam in normal subjects

Some central and peripheral effects of orally administered propranolol (60 mg), diazepam (5 mg) and placebo were compared in normal subjects. The central effects measured were changes in magnitude of the contingent negative variation (CNV) and subjective anxiety ratings; the peripheral effects were changes in heart rate, blood pressure, galvanic skin response and hand steadiness. After diazepam there was a decrease in CNV magnitude and in the level of subjective anxiety; there was a slight fall in blood pressure but little change in heart rate. After propranolol, on the other hand, there was no significant change in CNV magnitude or anxiety rating, but a significant fall in heart rate and systolic blood pressure. It is concluded that, at the dosage used, propranolol, unlike diazepam, does not affect the central mechanisms determining CNV magnitude or subjective anxiety. The relationship of this finding to the use of beta-adrenergic receptor blockers in clinical anxiety states is discussed.