Subtyping of panic disorder patients with bradycardia

Abstract

Purpose. Since clinical practice suggests that panic disorder may not be a homogeneous condition, a study was carried out to test the possible existence of different groups or subgroups of panic patients. Subjects and methods. Thirty-two panic patients (DSM-III-R) underwent lactate challenge in our laboratory and were assessed for heart rate, blood pressure, sweating and Acute Panic Inventory. Results. During the lactate challenge, patients complaining mainly of ‘cardiorespiratory’ symptoms ( N = 12) showed tachycardia and localized sweating. Conversely, patients complaining mainly of ‘pseudoneurological’ symptoms ( N = 16) showed bradycardia and generalized sweating. In both groups, Acute Panic Inventory scores were significantly higher during than before the panic attack, but the distribution of the scores was markedly different. Discussion and Conclusion. The results suggest that panic disorder may be a heterogeneous condition. Implications of these results to other phobic disorders, to Klein’s false suffocation alarm theory and to the ‘extended amygdala model’ are discussed.