Effect of beta-receptor blockade on anxiety with reference to the three-systems model of phobic behavior

14 phobic subjects were given propranolol (Inderal), atenolol (Tenormin) and placebo in a double-blind fashion according to a repeated measurement design. Subjects were exposed to their source of fear while their anxiety and cardiovascular responses (heart rate, blood pressure and peripheral temperature) were recorded. In accordance with the Three-Systems Model of fear and phobias, the subjects were divided into two groups of high and low physiological reactors, operationalized by the cardiovascular items in their anxiety pattern from a revised version of the Autonomic Perception Questionnaire (APQ). It was found that beta-blockade had the predicted effect on heart rate and peripheral temperature while diastolic blood pressure was unaffected. The systolic blood pressure finally was lowered for the low cardiovascular reactors. The subjectively rated anxiety rose consistently during exposure. There was no general effect of the beta-blocking drugs on subjective anxiety. For the high cardiovascular reactors propranolol was associated with a higher anxiety level.