An fMRI motor activation paradigm demonstrates abnormalities of putamen activation in females with panic disorder

BackgroundThe neurobiology of panic disorder is incompletely understood. The aim of this study was to determine if functional abnormalities of the putamen occur in panic disorder.MethodsActivation patterns of 12 female subjects with panic disorder were compared to 18 female healthy controls using functional MRI at 3 T. A motor activation paradigm was used to probe putamen function.ResultsA complex motor activation paradigm for the non-dominant hand revealed decreased activation of the bilateral putamen among subjects with panic disorder.LimitationsThe sample size was a relatively small cohort of non-depressed females. Further, some panic disorder subjects were taking medications and/or had comorbid conditions. However, second-level regression analyses did not reveal any correlations between medication use or comorbidity and activation patterns demonstrated by the non-dominant hand complex task. Finally, we used a post-hoc approach to determine the magnitude of global fMRI signal as a surrogate index of the global cerebral blood flow as a means of controlling for possible confounds from reduction of BOLD signal secondary to cerebral vasoconstriction resulting from possible hyperventilation among panic subjects. A more compelling approach would have been to record the respiratory data from subjects during scanning.ConclusionsOur findings suggest that putamen dysfunction occurs in at least some cases of panic disorder. We also provide preliminary evidence that a complex motor task for the non-dominant hand is a useful probe of putamen function in this disorder.