Differential reactivity to lactate infusions: the relative role of biological, psychological, and conditioning variables.

Nine patients with panic disorder experienced a lactate-induced panic attack, whereas nine controls did not. Higher preinfusion anxiety levels and heart rates were associated with panic disorder, and high baseline anxiety ratings were associated with atypical, severe lactate-induced panic attacks. Nevertheless, it was difficult to reconcile patients' and controls' reactivity to lactate as entirely secondary to baseline differences. Subjects differed qualitatively in the types of specific symptoms experienced and quantitatively in their anxiety and heart rate responses. In most cases, panic began with various central perceptual changes; peripheral cardiovascular and autonomic symptoms followed later. No patient rated a lactate-induced panic attack as identical to a naturally occurring attack. Not only did specific symptoms differ in their severity and order of production, but lactate-induced panic lacked the typical fears of dying, going crazy, or losing control. The results suggest that though environmental effects, expectancy biases, and baseline psychological states play salient roles in modifying the experience of a lactate-induced panic attack, they do not fully account for lactate sensitivity. The relative role that biological, psychological, and conditioning factors play in lactate-induced panic is discussed.