In a recent stimulating article, Dr Klein1(p306) boldly proposed that "many spontaneous panics occur when the brain's suffocation monitor erroneously signals a lack of useful air, thereby maladaptively triggering an evolved suffocation alarm system." Klein postulated that this is a physiological mechanism and that spontaneous panic attacks occur when the suffocation alarm threshold is pathologically lowered, or when psychosocial cues to suffocation are particularly salient. The theory spans a wide range of phenomena, although its primary focus is on spontaneous panic attacks.
We investigated the theory's main assumption that suffocation alarm hypersensitivity is a risk factor for panic disorder. Alarm hypersensitivity was operationalized by a recently developed measure of suffocation fear,2 which we administered to a sample of 179 university students. The sample's mean age was 20 years and two thirds were women. We reasoned that people with hypersensitive alarms are more likely to have their