Increased response to a putative panicogenic nocebo administration in female patients with panic disorder.

Experimental challenge studies may generate and test hypotheses regarding the pathophysiology of panic disorder and may serve to identify pathophysiologically relevant subtypes. It has been suggested that gender-related differences may be relevant in the development and maintenance of panic disorder. In a randomized double blind design the effects of placebo and sodium lactate administration in 14 female and 16 male patients with panic disorder and 23 healthy control subjects were compared using the Acute Panic Inventory (API) score and derived formal criteria for a panic attack. Panic attack frequency following sodium lactate was 76.6% in the patient group. Although control subjects had a lactate-induced increase in the API score as well, this effect was much weaker. No panic attacks occurred in patients with panic disorder or healthy control subjects receiving a placebo. However, a gender effect was observed in the putative panicogenic placebo condition: female patients with panic disorder had more subthreshold panic anxiety as measured with the API score. The data give evidence for an increased nocebo response in female patients with panic disorder.