Frequency-dependent alterations in the amplitude of low-frequency fluctuations in social anxiety disorder

Background: Recent studies on resting state functional magnetic resonance imaging (fMRI) have found an abnormal temporal correlation between low frequency oscillations (LFO) in social anxiety disorder (SAD). However, alterations in the amplitudes of these LFO remain unclear. Methods: This study included 20 SAD patients and 20 age-, gender-, and education matched healthy controls. Resting state fMRI data were acquired using a gradient echo echo planar imaging sequence, and the amplitudes of LFO were investigated using the amplitude of low frequency fluctuation (ALFF) approach. Two frequency bands (slow-5. 0.01-0.027 Hz; slow-4. 0.027-0.073 Hz) were analyzed. Results: Significant differences in ALFF were observed between the two bands in widespread regions including the poslceraral gyros, preceraral gyros, medial prefrontal cortex (MPFC), orbilofrontal cortex, hippocampus, thalamus, caudate, pill:amen, and insula. Compared with the healthy controls, the SAD patients showed lower ALFF. in the dorsolaleral prefrontal cortex (DLPFC), MPFC, superior temporal gyrus, and insula but higher ALFF in the middle occipital gyrus. Furthermore, we found that the SAD patients had reduced ALFF in the MPFC in the slow-5 band. Limitation: The small sample size may decrease the statistical power of the results. Conclusions: SAD patients had frequency-dependent alteration in intrinsic brain activity. This finding may provide insights into the understanding of the pathophysiology of SAD. (C) 2014 Elsevier B.V. All tights reserved