Neural mechanisms of symptom improvements in generalized anxiety disorder following mindfulness training

Mindfulness training alters brain activity in regions involved in emotion regulation among people with generalized anxiety disorder (GAD). In a preliminary study, 26 GAD patients were randomly assigned to either an 8-week Mindfulness-Based Stress Reduction (MBSR) program or a stress management education control. At baseline, GAD patients showed higher amygdala activation than healthy participants when viewing neutral faces, indicating heightened reactivity to ambiguous stimuli. After both interventions, amygdala activation to neutral faces decreased. MBSR, but not the control, led to greater increases in ventrolateral prefrontal cortex (VLPFC) activity and strengthened amygdala-prefrontal functional connectivity. These brain changes correlated with reductions in anxiety scores, suggesting clinical relevance. The shift from negative to positive amygdala-prefrontal coupling may represent a unique mechanism of mindfulness.

Study at a glance

Abstract

Mindfulness training aims to impact emotion regulation. Generalized anxiety disorder (GAD) symptoms can be successfully addressed through mindfulness-based interventions. This preliminary study is the first to investigate neural mechanisms of symptom improvements in GAD following mindfulness training. Furthermore, we compared brain activation between GAD patients and healthy participants at baseline. 26 patients with a current DSM-IV GAD diagnosis were randomized to an 8-week Mindfulness Based Stress Reduction (MBSR, N = 15) or a stress management education (SME, N = 11) active control program. 26 healthy participants were included for baseline comparisons. BOLD response was assessed with fMRI during affect labeling of angry and neutral facial expressions. At baseline, GAD patients showed higher amygdala activation than healthy participants in response to neutral, but not angry faces, suggesting that ambiguous stimuli reveal stronger reactivity in GAD patients. In patients, amygdala activation in response to neutral faces decreased following both interventions. BOLD response in ventrolateral prefrontal regions (VLPFC) showed greater increase in MBSR than SME participants. Functional connectivity between amygdala and PFC regions increased significantly pre- to post-intervention within the MBSR, but not SME group. Both, change in VLPFC activation and amygdala-prefrontal connectivity were correlated with change in Beck Anxiety Inventory (BAI) scores, suggesting clinical relevance of these changes. Amygdala-prefrontal connectivity turned from negative coupling (typically seen in down-regulation of emotions), to positive coupling; potentially suggesting a unique mechanism of mindfulness. Findings suggest that in GAD, mindfulness training leads to changes in fronto-limbic areas crucial for the regulation of emotion; these changes correspond with reported symptom improvements.