Acute effects of 150 mg caffeine on subjective, physiological, and behavioral components of anxiety in panic disorder and healthy controls - A randomized placebo-controlled crossover trial.

Background: Caffeine in doses above 400 mg, approximately four cups of coffee, induces panic attacks in 50% of individuals with panic disorder (PD) and elevates anxiety, but it is not known how individuals with PD respond to normally consumed doses or how caffeine interacts with emotional tasks.

Aims: We hypothesized that 150 mg caffeine would increase subjective anxiety (primary outcome) as well as interoceptive attention and anxiety from bodily signals in patients with PD, and more so than in healthy controls (HCs). Additional analyses targeted panic attacks, emotional reactivity, avoidance behavior, and subjective exteroceptive attention.

Methods: Twenty-nine patients with PD and 53 HC with low habitual caffeine consumption (⩽300 mg/week) abstained from caffeine 36 h before receiving 150 mg caffeine or placebo in a double-blind randomized crossover design 2-14 days apart.

Results: Contrary to our hypotheses, caffeine did not increase subjective anxiety, interoceptive attention, or anxiety from interoceptive signals. Only one panic attack was noted, in the PD group after caffeine intake during the emotional reactivity task. In both PD and HC, caffeine increased skin conductance responses to neutral and emotional faces, augmented costly avoidance behavior, and impaired exteroceptive attention. These results indicate that low caffeine doses do not have differential anxiogenic effects in patients with PD and HC at rest, and that they increase arousal and avoidance behavior in both PD and healthy individuals.

Conclusions: In conclusion, we suggest that recommendations for caffeine abstinence for patients with PD should be based on higher doses and ideally on individual assessments.