Cognitive explanation of why beta blockers are effective for anxiety Beta blockers essentially reduce physical effects of anxiety and panic disorder, but there is no proof that there is a direct effect on anxiety. Some scientists believe there is an indirect effect.

What is the cognitive explanation of the fact that a reduction in symptoms causes a reduction in anxiety?
One possibility is related to the Two-Factor theory of emotion. The theory describes how emotion is a product of both cognitive and physiological factors. Essentially, the mind tries to determine what emotion it is feeling by analyzing the body. By antagonizing epinephrine, they kind of inhibit the sympathetic nervous system. So, when a person would otherwise feel anxiety it would be associated with the effect of epinephrine. Without that cue, they would possibly interpret their feelings differently, as feeling less anxious.

http://psycnet.apa.org/journals/rev/69/5/379/