PROJECT SUMMARY Alcohol and other drug use (AOD) lapses in early substance use disorder (SUD) recovery typically arise from interactions between aversive affective states and stressors that together elicit urges to use. A central goal of first-line cognitive-behavioral SUD treatments is to strengthen affective and cognitive control to increase individuals’ ability to override impulses to use AOD. Yet certain automatic physiological processes compromised by SUD dynamically interact with internal affective states and environmental cues to undermine effortful cognitive control and outcompete cognitive goals to avoid substance use. Heart rate variability biofeedback (HRV BFB) is a biobehavioral intervention involving rhythmic breathing at resonance frequency (RF) that stimulates the body’s baroreflex mechanism to offset these psychophysiological deficits. The autonomic normalization effected by RF breathing is thought to bolster cognitive control efforts by interrupting or dampening automatic-visceral reactions that can undermine treatment gains, and in doing so support better decision-making, motivation, reductions in craving, and shifts in attention allocation. Previous studies of HRV BFB have focused on positive behavioral effects that accrue over a series of weeks or months, rather than ‘in-the-moment’. These chronic behavior changes, although clinically valuable, are labor and time intensive to elicit, reducing the likelihood of large-scale uptake of the intervention. Further, first-generation HRV BFB’s regular daily practice model is likely to only partially mitigate the intense momentary bouts of emotion dysregulation that are triggers for AOD use in those in early SUD recovery. In contrast, recent studies have demonstrated that a brief exposure to RF breathing in anticipation of psychosocial stress, or during induced stress, helps to control physiological arousal, reduce state anxiety, and improve cognitive performance. We posit that such bursts of in-the-moment HRV BFB practice could serve as a potent SUD treatment tool that helps individuals self-regulate intense emotions when needed most. Excitingly, recent advances in the field have given rise to small, lightweight, wearable biosensors that can allow wearers to do HRV BFB on-the-go. These devises also have the capacity to function as a just-in-time intervention by prompting in-the-moment HRV BFB practice when autonomic hyperarousal is detected, to buffer salient triggers and urges to use AOD. This application builds on a body of preliminary work speaking to HRV BFB’s potential as an addendum to first-line SUD treatments by exploring for the first time in this disorder this cutting edge, second-generation, ambulatory, HRV BFB technology. Our specific aims include, 1) assessing ambulatory HRV BFB’s uptake by individuals with SUD, 2) testing day-level effects of in-the-moment HRV BFB practice on affective states and substance use, and 3) testing the accumulative effects of scheduled daily HRV BFB practice, in-the-moment HRV BFB practice, and their interaction, on substance use.

PROJECT NARATIVE Heart rate variability biofeedback (HRV BFB) is an exciting biobehavioral intervention involving rhythmic breathing at resonance frequency that stimulates cardiovascular regulatory systems to help individuals better regulate affect and bolster cognitive control. This intervention has already shown its potential as a substance use disorder (SUD) treatment tool, but practical limitations of its accessibility, labor intensiveness, and cost have previously prevented this intervention from going to scale. Second-generation, ambulatory HRV BFB technology, however, has overcome these limitations and now allows patients to practice HRV BFB in-the-moment when its needed most – we aim to pilot test this technology for the first time with individuals with SUD.