Freezing reaction in panic disorder patients associated with anticipatory anxiety.

BACKGROUND: Anticipatory anxiety can be described as a conditioned response with a defensive posture of freezing and autonomic activation. The purpose of this study was to assess the postural control analysis and autonomic activation in panic disorder (PD) patients presented with visual stimuli.
METHODS: PD patients (n=29) and healthy controls (n=27) stood on a force platform while viewing a series of anxiogenic, mutilation, and neutral pictures. Skin conductance responses and the displacements of the center of pressure were measured.
RESULTS: Overall, the PD patients demonstrated significantly reduced body sway, increased mean power frequency, and increased skin conductance compared to control group throughout the experiment (P<.05). PD patients also showed a negative correlation between anticipatory anxiety and mean sway area throughout the experiment. However, there was no significant difference in body sway velocity compared to healthy controls while viewing the anxiogenic block of pictures or the neutral block.
CONCLUSIONS: Our data shows that PD patients experiencing anticipatory anxiety may present with lower mobility, consistent with the freezing behavior of the defense cascade. The data also shows that PD patients do not have a postural instability when confronted with specific anxiogenic context. The importance of this study is that it objectively demonstrates freezing-like behavior in PD patients.