A Biofeedback Technique to Reduce Anxiety among Patients with AN Adolescents with recent-onset disease had more rapid results.

Reprinted from Eating Disorders Review
November/December Volume 25, Number 6
©2014 IAEDP

A recent pilot study used heart rate variability (HRV) biofeedback training as a method of reducing anxiety among patients with eating disorders (J Eat Disord 2014; 2:17). The idea behind biofeedback is that, by harnessing the power of the mind and becoming aware of what's going on inside the body, an individual can gain more control over his or her health. 

Heart rate variability (HRV) is the normal phenomenon in which time between one heartbeat and the next changes. Much of this variability is determined by the action of breathing: the pulse speeds up with inspiration and slows down with expiration. Most studies have shown that patients with AN have elevated HRV compared with normal controls. In an effort to alter the variability in heart rate, Dr. Barbara Scolnick and colleagues at Boston University offered HRV biofeedback to 25 inpatients with diagnoses of anorexia nervosa (AN), bulimia nervosa, and binge eating disorder.

HRV biofeedback training uses the breathing aspects of Eastern mediation techniques, and the results are shown on a digital display. A pulse monitor or electrocardiographic lead is placed on the subject and the resulting pulse or tracing and inter-beat intervals are shown on a computer monitor. Slow breathing exaggerates HRV, and at a breathing rate of approximately 6 breaths per minute, the pattern reaches coherence, or forms a sine wave (The sine wave or sinusoid is a mathematical curve that describes a smooth repetitive oscillation.) 

Twenty-four patients agreed to participate in the study. The researchers used a commercially available product, emWave® pro (Heart Math LLC, Boulder Creek, CA) and a computer. Most sessions lasted 10 minutes and were conducted daily or every other day as long as the participant was an inpatient, for up to 12 sessions per patient.

No serious side effects were reported, although one patient, a 24-year-old woman with restricting-type AN and comorbid bipolar disorder, felt faint while performing the feedback portion of the session. Four other participants asked to leave the study early because they did not see any benefits. 

One result that surprised the authors was that success with the technique correlated inversely with aging. Most young adolescents were able to achieve 100% coherence on the first session and seemed to enjoy what one teen called “my unique ability,” but this did not necessarily translate to decreased anxiety. The group of patients who were most enthusiastic about the biofeedback test were in their 20s and highly motivated for change. While none of these patients achieved coherent patterns immediately, eventually they did so and could generate a sine wave by “slowing their breathing and thinking comforting thoughts.” Five patients older than 30 struggled to generate coherence but found the slow breathing calming. Notably, ability to successfully achieve coherence did not appear closely related to subjective benefit.

The hope for a biomarker

There is increased interest in underlying biologic mechanisms and disease markers in psychiatry. The mechanism that transforms this state into one of self-driven starvation has never been explained. The authors note that if a substantial difference is seen between HRV in healthy adolescents, compared to those with AN, HRV might act as a biomarker for the disease.