Early effects of exposure-based cognitive behaviour therapy on the neural correlates of anxiety.

Exposure-based cognitive-behaviour therapy (CBT) for anxiety disorders is an effective intervention, but the brain mechanisms driving recovery are largely unknown. In this experimental medicine study, we investigated to what degree CBT affects neural markers of anxiety at an early stage of treatment, to identify dynamic mechanistic changes which might be crucial in the process of recovery as opposed to those seen following full treatment completion. In a randomised controlled trial, unmedicated patients with panic disorder either received four weekly sessions of exposure-based CBT (N = 14) or were allocated to a waiting group (N = 14). Symptom severity was measured before and after the intervention. During functional magnetic resonance imaging (fMRI), patients performed an emotion regulation task, either viewing negative images naturally, or intentionally down-regulating negative affect using previously taught strategies. Four-session CBT led to marked reductions in symptoms and 71% of patients reached recovery status (versus 7% in the control group). This intervention normalised brain hyperactivation previously seen in panic disorder, particularly in areas linked to threat monitoring, fear memory, and maladaptive emotion regulation, such as amygdala, dorsomedial and dorsolateral prefrontal cortex, and temporal gyrus. Our findings suggest that optimal treatment doses for panic disorder might be much lower than previously thought. Furthermore, this is the first study to show that neural markers of anxiety change very early during CBT, highlighting potential neural mechanisms that might drive clinical recovery. Such knowledge is important for the development of more compact combination treatments targeting these mechanisms more effectively. (Neural Effects of Cognitive-behaviour Therapy in Panic Disorder; clinicaltrials.gov; NCT03251235).