Abstract
Reduced Environmental Stimulation Therapy (REST) alters the balance of sensory input to the nervous system by systematically attenuating sensory signals from visual, auditory, thermal, tactile, vestibular, and proprioceptive channels. Previous research from our group has shown that REST via floatation acutely reduces anxiety and blood pressure (BP) while simultaneously heightening interoceptive awareness in clinically anxious populations. Anorexia nervosa (AN) is an eating disorder characterized by elevated anxiety, distorted body representation, and abnormal interoception, raising the question of whether REST might positively impact these symptoms. However, this approach has never been studied in eating disorders, and it is unknown whether exposure to floatation REST might worsen AN symptoms. To examine these possibilities, we conducted an open-label study to investigate the safety and tolerability of REST in AN. We also explored the acute impact of REST on BP, affective symptoms, body image disturbance, and interoception. Twenty-one partially weight-restored AN outpatients completed a protocol involving four sequential sessions of REST: reclining in a zero-gravity chair, floating in an open pool, and two sessions of floating in an enclosed pool. All sessions were 90 min, approximately 1 week apart. We measured orthostatic BP before and immediately after each session (primary outcome), in addition to collecting BP readings every 10 min during the session using a wireless waterproof system as a secondary outcome measure. Each participant’s affective state, awareness of interoceptive sensations, and body image were assessed before and after every session (exploratory outcomes). There was no evidence of orthostatic hypotension following floating, and no adverse events (primary outcome). Secondary analyses revealed that REST induced statistically significant reductions in BP (p < 0.001; Cohen’s d, 0.2–0.5), anxiety (p < 0.001; Cohen’s d, >1) and negative affect (p < 0.01; Cohen’s d, >0.5), heightened awareness of cardiorespiratory (p < 0.01; Cohen’s d, 0.2–0.5) but not gastrointestinal sensations, and reduced body image dissatisfaction (p < 0.001; Cohen’s d, >0.5). The findings from this initial trial suggest that individuals with AN can safely tolerate the physical effects of REST via floatation. Future randomized controlled trials will need to investigate whether these initial observations of improved anxiety, interoception, and body image disturbance occur in acutely ill AN populations.Clinical Trial RegistrationClinicalTrials.gov; Identifier: NCT02801084 (April 01, 2016).
Highlights
Anorexia nervosa is an unusually deadly disorder with the highest mortality risk of all psychiatric disorders (Sullivan, 1995; Suokas et al, 2013), carrying an estimated standardized mortality rate two to three times higher than schizophrenia, bipolar disorder, and unipolar depression (Arcelus et al, 2011; Hoang et al, 2014)
Before assessing the secondary outcome measure of blood pressure (BP), we evaluated the reliability of the QardioArm vs. CASMED devices was evaluated for each session and each position using the Pearson correlation coefficient, and for all sessions and positions combined using the intraclass coefficient (ICC), determined by the sum of betweensubject random-effect variance components divided by the total random variance components obtained from a random-effects model with fixed intercept and random intercepts of subject, session, and measure
The current Body mass index (BMI) average for the group was in the normal range, there was evidence of residual Anorexia nervosa (AN) symptoms based on higher-than-normal Eating Disorder Examination Questionnaire (EDE-Q) global scores and elevated trait anxiety on the State-Trait Anxiety Inventory (STAI)-trait scale (Table 1)
Summary
Anorexia nervosa is an unusually deadly disorder with the highest mortality risk of all psychiatric disorders (Sullivan, 1995; Suokas et al, 2013), carrying an estimated standardized mortality rate two to three times higher than schizophrenia, bipolar disorder, and unipolar depression (Arcelus et al, 2011; Hoang et al, 2014). Many AN patients die from complications associated with starvation, others die as a result of suicide (Keshaviah et al, 2014) Of those remaining, 20% are chronically ill (Steinhausen, 2002; Bulik et al, 2007; Lock, 2010; McElroy et al, 2015), with relapse rates as high as 30–50% following inpatient treatment (Khalsa et al, 2017; Berends et al, 2018). One especially concerning finding is that anxiolytic medications that are effective at reducing anxiety over the short term in anxiety-disordered patients, such as benzodiazepines, are ineffective in lowering the anxiety associated with AN (Steinglass et al, 2014) Alternative anxiolytic medications, such as beta-blockers, are often contraindicated in these patients due to the compensatory bradycardia that often follows chronic caloric restriction in AN patients. Additional treatments which can effectively ameliorate affective disturbances in AN are needed
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