Comparison of panic disorder with and without comorbid major depression by using brain structural magnetic resonance imaging.

BACKGROUND: Strong lifetime and current comorbidity occur between panic disorder and depression. However, no study has examined the influence of comorbid depression on brain structural characteristics in panic disorder patients. We aimed to compare gray matter (GM) volume and white matter (WM) connectivity in panic disorder patients with and without depression.
METHODS: Twenty-one panic disorder patients without comorbid major depression (PD-D) and seventeen panic disorder patients with major depression (PD+D) were investigated. The Panic Disorder Severity Scale (PDSS) and Beck Depression Inventory (BDI) were assessed for all subjects. Voxel Based Morphometry 5 toolbox and Tract-Based Spatial Statistics were used.
RESULTS: Compared to the PD-D group, GM volumes of patients with PD+D were significantly increased in a cluster located across the left cingulate gyrus, right medial frontal gyrus, and left paracentral lobule. Clinical symptom severity such as PDSS and BDI scores showed positive correlation with GM volumes in the PD+D group. Of the highlighted regions, the left posterior cingulate gyrus demonstrated both a GM volume difference between the groups and a positive correlation of GM volume with symptom severity in the PD+D group. Fractional anisotropy values were significantly higher across almost all the WM tracts in the PD+D group compared to the PD-D group.
CONCLUSION: Alteration of GM volume and WM connectivity was associated with comorbid depression in panic disorder patients in this study. These findings suggest that distinct structural characteristics may be related to comorbid depression occurring in the context of panic disorder.