Defensive Mobilization During Anticipation of Symptom Provocation: Association With Panic Pathology

Anxious apprehension about feared body symptoms is thought to play a crucial role in the development, chronicity, and treatment of panic disorder (PD). In this study, we therefore aimed to elucidate the role of defensive reactivity to anticipated unpleasant symptoms in PD that can contribute to a better understanding of pathomechanisms of PD as well as identification of potential targets in PD-focused interventions. By measuring amygdala-dependent potentiation of the startle reflex, we aimed to investigate whether 1) patients with PD exhibit a specifically increased defensive reactivity to anticipated unpleasant body symptoms and 2) whether clinical severity of panic symptomatology varies with magnitude of defensive activation.

Defensive mobilization to anticipated threat was investigated in 73 patients with a primary diagnosis of PD with agoraphobia (PDA) and 52 healthy control subjects. Threat of symptom provocation was established by a standardized hyperventilation task and contrasted to threat of shock to the forearm of the participant.

Patients with PDA and healthy control subjects did not differ in their defensive responses during anticipation of shock. In contrast, patients with severe PDA as compared with healthy control subjects exhibited increased defensive response mobilization and reported more anxiety and panic symptoms during anticipation of feared body symptoms. Moreover, startle potentiation during anticipation of hyperventilation covaried with the severity of panic symptomatology.

The present findings suggest that increased defensive mobilization during anticipation of body symptoms is a neurobiological correlate of severe PDA that should be specifically targeted in PD interventions and might be used to monitor treatment success.