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

Background: The 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. Methods: Activation 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. Results: A complex motor activation paradigm for the non-dominant hand revealed decreased activation of the bilateral putamen among subjects with panic disorder. Limitations: The 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. Conclusions: Our 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. Published by Elsevier B.V.