Heart Rate Variability Predicts Therapy Outcome in Anxiety Disorders: The Role of Inhibitory Learning

Exposure therapy has been shown to be useful for the treatment of anxiety disorders. However, there are individual differences in the extent to which this intervention is effective in reducing symptoms, and a substantial number of patients may experience a return of fear (ROF). The factors associated with successful therapy outcomes are an important topic of investigation as these factors might influence the nature of the interventions as well as enhance our understanding of the process associated with the disorder and its treatment. Here, we investigated the effect of resting heart rate variability (HRV) on ROF following exposure therapy in social phobics. In particular, using path modeling, we assessed the hypothesis that resting HRV prospectively predicts inhibitory learning, which, in turn, prospectively predicts ROF at follow-up. Forty adult participants (60% female) diagnosed with Social Anxiety Disorder were assigned to a single massed exposure therapy session. Self-reported behavioral and physiological responses were recorded pre-treatment, immediately following treatment, and at one-month follow-up. The Personalized Implicit Association Task (PIAT) was used as an implicit measure of inhibitory learning, and HF-HRV was taken as a measure of vagal activity. Results revealed that those with high pre-treatment HRV reported less negative implicit attitude towards public speaking after exposure (b = -0.044, p =.047) and showed reduced residual symptoms one month after treatment. (b = 2.247, p =.013). Taken together these results support exposure therapy models that emphasize the importance of inhibitory learning in extinction and are consistent with research linking HRV to inhibition.