Behavioural and subjective effects of beta-adrenergic blockade in phobic subjects

It has been suggested that reversal of stress-induced tachycardia by beta-adrenergic blockade might be of benefit in the treatment of phobias. This was tested in a double-blind cross-over trial by exposing 22 female volunteers with spider or snake phobias to their phobic object 1 1/2 hours after administration of either tolamolol 200 mg, diazepam 10 mg or placebo. Although tolamolol abolished the stress-induced tachycardia, it had no beneficial behavioural or subjective effects. In contrast, diazepam, which had no significant effect on heart rate, improved behavioural performance. Subjective measures were more influenced by order effect than by medication.