Neuroplasticity in response to cognitive behavior therapy for social anxiety disorder.

K N T Månsson,C-J Boraxbekk,T Furmark,A Salami,G Andersson,P Carlbring,A Frick

doi:10.1038/tp.2015.218

Abstract

Patients with anxiety disorders exhibit excessive neural reactivity in the amygdala, which can be normalized by effective treatment like cognitive behavior therapy (CBT). Mechanisms underlying the brain's adaptation to anxiolytic treatments are likely related both to structural plasticity and functional response alterations, but multimodal neuroimaging studies addressing structure–function interactions are currently missing. Here, we examined treatment-related changes in brain structure (gray matter (GM) volume) and function (blood–oxygen level dependent, BOLD response to self-referential criticism) in 26 participants with social anxiety disorder randomly assigned either to CBT or an attention bias modification control treatment. Also, 26 matched healthy controls were included. Significant time × treatment interactions were found in the amygdala with decreases both in GM volume (family-wise error (FWE) corrected PFWE=0.02) and BOLD responsivity (PFWE=0.01) after successful CBT. Before treatment, amygdala GM volume correlated positively with anticipatory speech anxiety (PFWE=0.04), and CBT-induced reduction of amygdala GM volume (pre–post) correlated positively with reduced anticipatory anxiety after treatment (PFWE⩽0.05). In addition, we observed greater amygdala neural responsivity to self-referential criticism in socially anxious participants, as compared with controls (PFWE=0.029), before but not after CBT. Further analysis indicated that diminished amygdala GM volume mediated the relationship between decreased neural responsivity and reduced social anxiety after treatment (P=0.007). Thus, our results suggest that improvement-related structural plasticity impacts neural responsiveness within the amygdala, which could be essential for achieving anxiety reduction with CBT.

Highlights

Time × treatment interactions indicated that left amygdala gray matter (GM) volume and right amygdala BOLD response decreased significantly more with cognitive behavior therapy (CBT) compared with the attention bias modification (ABM) control treatment
Both GM volume and neural responsivity in the bilateral amygdala diminished after effective treatment
Left amygdala GM volume was positively associated with symptom severity before treatment, and amygdala volume decreased significantly with CBT, correlating positively with symptom improvement in both hemispheres

Summary

INTRODUCTION

A recent large study found that both GM volume and neural responsivity in the amygdala were associated with symptoms of separation anxiety,[13] suggesting dependence between anxietyrelated brain structure and function. We expected concomitant treatment-related changes in GM volume and functional response example, LSAS-SR).[40] We were interested in state-related social anxiety,[44] so after the MRI assessment the participants performed a 2-min public speaking task. Both after the initial anatomical image acquisition, and prior to the speech, the participants rated subjective units of discomfort.

RESULTS

DISCUSSION

CONFLICT OF INTEREST