Somatic symptoms and physiologic responses in generalized anxiety disorder and panic disorder: an ambulatory monitor study.
BACKGROUND: Physiologic responses of patients with anxiety disorders to everyday events are poorly understood. OBJECTIVE: To compare self-reports and physiologic recordings in patients with panic disorder (PD), patients with generalized anxiety disorder (GAD), and nonanxious controls during daily activities. DESIGN: Participants underwent four 6-hour recording sessions during daily activities while wearing an ambulatory monitor. Physiologic and subjective data were recorded every 30 minutes and during subject-signaled periods of increased anxiety or tension or panic attack. SETTING: Participants' everyday environment. PARTICIPANTS: Twenty-six patients with PD and 40 with GAD, both without substantial comorbidity, and 24 controls. INTERVENTIONS: Recordings obtained during everyday activities. MAIN OUTCOME MEASURES: Recordings of heart interbeat intervals, skin conductance levels, respirations, motion, and ratings of subjective somatic symptoms and tension or anxiety. RESULTS: Patients with anxiety disorders rated higher on psychic and somatic anxiety symptoms than did controls. Common to both anxiety disorders was diminished autonomic flexibility that manifested itself throughout the day, accompanied by less precise perception of bodily states. The main differences between patients with PD and GAD were a heightened sensitivity to body sensations and more frequent button presses. There also was a trend toward heightened basal arousal in patients with PD, manifesting itself in a faster heart rate throughout the day. CONCLUSIONS: Patients with PD or GAD are more sensitive to bodily changes than nonanxious individuals, and patients with PD are more sensitive than those with GAD. Patients with PD experience more frequent distress than those with GAD and controls, but their physiologic responses are comparable in intensity. The findings suggest that the perception of panic attacks reflects central rather than peripheral responses. The diminished autonomic flexibility observed in both anxiety conditions may result from dysfunctional information processing during heightened anxiety that fails to discriminate between anxiety-related and neutral inputs.