Wearable Emotion Prosthetics for Post Traumatic Stress Disorder

Overview

Involuntary stress reactions including hyper-reactivity and dissociation are key diagnostic features of many psychiatric disorders, are difficult to treat, and predict poor outcomes in conventional and neurobehavioral interventions. Here, we evaluate the extent to which a novel intervention, Tuned Vibroacoustic Stimulation (TVS), capitalizing on a preserved neurocircuitry for sympathetic and parasympathetic system activity can be used to modify arousal responses, overriding otherwise prepotent negative stress reactions. PTSD has been characterized by dysregulated responses to stress as a result of severe acute or chronic trauma resulting in significantly impaired functioning, quality of life, and morbidity/mortality. Physiologically, PTSD severity has been associated with elevated sympathetic tone and low heart rate variability suggesting that parasympathetic tone is suppressed. Lower heart rate variability specifically, as a measure of parasympathetic tone, is closely associated with impaired performance and resilience. In our first study (in review), we showed that in some individuals, TVS is associated with increased heart rate variability and performance under stress along with reduced subjective stress. These results suggest that TVS could provide some therapeutic benefit in PTSD. N=100 individuals with mild-moderate PTSD (as assessed by PCL-5/CAP5), at least half of which are military Veterans, will be assessed physiologically during active interventions. Mechanisms of attentional focus on cognitive and emotional stimuli will be assessed. Participants will also have a real-world intervention to determine if TVS helps alleviate stress, symptoms, and medication burden in the real world when stress has been identified. Success will suggest a new intervention pathway for a traditionally treatment-resistant dimension of psychopathology.

This protocol will examine and elucidate a mechanistic model for tuned vibroacoustic stimulation (TVS), an exteroceptive cue that has been shown to reduce subjective and physiological indicators of stress and increase behavioral performance in healthy subjects. In this study, we will test whether TVS can reduce subjective and physiological signs of stress, improve performance, alleviate symptoms, and reduce medication burden in adults with post-traumatic stress disorder (PTSD). This protocol will also examine whether software that cues TVS in response to biological stress markers helps users detect, regulate, and develop long-term resilience to stress outside of the laboratory. Aim 1: Examine how TVS alters calmness and stress markers. Our overall hypothesis is that TVS, in combination with some other task, increases performance on that task by decreasing stress and increasing emotion regulation. Hypothesis 1: TVS during an attention task will lead to decreased GSR, increased HRV, and increases in prefrontal gamma and theta band EEG, along with improved behavioral performance on a focused attention, working memory and emotional information processing task. TVS will also reduce subjective stress levels. Aim 2: Examine the extent to which software, which monitors real time biological stress markers of users, and in response, automatically signals wearable hardware to deliver TVS when user is stressed, will be able to help users detect, regulate, and develop long-term resilience to stress outside the laboratory for two weeks. Hypothesis 2.1: Evaluate whether subjects with PTSD in the real world will use our software to detect and alert them of stress dynamically and if this is associated with stress regulation. Hypothesis 2.2: Examine whether TVS is associated with stress regulation. Hypothesis 2.3: Examine whether TVS is associated with reduction in PTSD symptoms and, possibly, medication burden. Over 39 million Americans suffer from excessive chronic stress, which can be psychologically and physically debilitating (Salleh, 2008). Untreated chronic stress plays a role in the development of major illnesses such as cardiovascular disease, obesity, anxiety and depression (Dallman et al., 2006; Swaab, Bao, \& Lucassen, 2005). Post-traumatic stress disorder (PTSD), is a severe mental illness that impacts millions of veterans and civilians nationwide. Existing treatments for chronic stress and PTSD are often ineffective, have adverse effects, and are prohibited by cost, time-commitment, and accessibility, resulting in high rates of substance abuse and suicide (Jonas et al., 2013; Watts et al., 2013). Stress in general, and PTSD more specifically, are characterized by hyper-reactivity in the sympathetic nervous system which is associated with increased arousal and vigilance, and compromised reactivity of the parasympathetic nervous system, which helps to regulate emotion and stress responses (Kibler, Tursich, Ma, Malcolm, \& Greenbarg, 2014; Lehrer \& Gevirtz, 2014). PTSD has been characterized by dysregulated responses to stress as a result of severe acute or chronic trauma resulting in significantly impaired functioning, quality of life, and morbidity/mortality. Physiologically, PTSD severity has been associated with elevated sympathetic tone and low heart rate variability suggesting that parasympathetic tone is suppressed. HRV is widely used as a biomarker for the coordinated activity of the sympathetic and parasympathetic nervous symptom. A calmer, less stressful state is typically marked by increased HRV, likely attributed to respiration based parasympathetic stimulation (Grossman \& Taylor, 2007). GSR is also a reliable index for sweat gland activity and changes in activation level of the sympathetic nervous system, and GSR usually increases with higher levels of stress (Mohan, Sharma, \& Bijlani, 2011). EEG changes, such as elevated prefrontal gamma and theta, have also been associated with state of relaxed alertness. Our initial data (submitted) suggest that for some individuals, TVS can boost heart rate variability and performance under stress while reducing subjective stress. These results suggest that TVS could provide some therapeutic benefit in PTSD. Large scientific literature supports the role of vibration in regulating stress physiology (Takahashi, Ohashi, \& Yokoyama, 2011; M. Uchikune, 2002; M. Uchikune, 2004). For example, slow whole-body vibration, in the 0.01 to 0.3 Hz range, is associated with increased ratings of pleasantness and increased parasympathetic tone (M. Uchikune, 2002; M. Uchikune, 2004). Stimulation at about 100 Hz has been shown to activate the posterior insula (Coghill et al., 1994) which is associated with increased attention to interoception, as promoted in many meditative traditions. Transcutaneous targets for the vibration frequencies have also been identified, including stellate ganglion and vagus nerve (Cipriano et al., 2014; Fang et al., 2016). In this study, we will be testing the potential for TVS to increase well-being (subjective calmness, increased performance, and physiological reactivity) in the PTSD population. Positive results would suggest that reduction in symptomatology may be possible without effort, and in lieu of specific interventions with medications or psychotherapy. A wearable form of TVS technology will be examined in a real-world setting. We will use ambulatory assessment to detect physiological indications of stress unique to each user and to provide user-optimized TVS, examining whether it increases parasympathetic nervous system reactivity in response to stress, thus decreasing subjective stress just as a user's stress begins to increase.