Aberrant limbic and salience network resting-state functional connectivity in panic disorder without comorbidity

Panic disorder (PD) is a prevalent and debilitating disorder but its neurobiology is still poorly understood. We investigated resting-state functional connectivity (RSFC) in PD without comorbidity in three networks that have been linked to PD before. This could provide new insights in how functional integration of brain regions involved in fear and panic might relate to the symptomatology of PD.

Eleven PD patients without comorbidity and eleven pair-wise matched healthy controls underwent resting-state fMRI. We used seed regions-of-interest in the bilateral amygdala (limbic network), the bilateral dorsal anterior cingulate cortex (dACC) (salience network), and the bilateral posterior cingulate cortex (default mode network). RSFC of these areas was assessed using seed-based correlations. All results were cluster corrected for multiple comparisons (Z>2.3, p<.05).

Abnormalities were identified in the limbic network with increased RSFC between the right amygdala and the bilateral precuneus in PD patients. In the salience network the dACC demonstrated altered connectivity with frontal, parietal and occipital areas.

The small sample size and hypothesis-driven approach could restrict finding additional group differences that may exist. Other caveats are reflected in the use of medication by two participants and the acquisition of the resting-state scan at the end of a fixed imaging protocol.

We found altered RSFC in PD between areas involved in emotion regulation and emotional and somatosensory stimulus processing, as well as an area engaged in self-referential processing, not implicated in models for PD before. These findings extend existing functional neuroanatomical models of PD, as the altered RSFC may underlie increased sensitivity for bodily symptoms.