The effects of biofeedback in diabetes and essential hypertension
ABSTRACT
The metabolic syndrome is likely to develop in patients in whom genetic predisposition, chronic stress, negative emotion, and unhealthy lifestyle habits converge. In light of the psychophysiologic aspect of most of these factors, biofeedback, relaxation, and other psychophysiologic interventions have been studied and used in patients with elements of the metabolic syndrome, particularly diabetes and hypertension. This article reviews the rationale and evidence for biofeedback for the treatment of diabetes and hypertension, which has been shown to effectively lower blood glucose and blood pressure in numerous studies. Patients with prehypertension may be a particularly appropriate target population for biofeedback for blood pressure reduction. Further research is needed to guide identification of the best candidates for psychophysiologic intervention for these conditions, although patient readiness for change is a clear prerequisite.
BIOFEEDBACK IN ESSENTIAL HYPERTENSION
Biofeedback-assisted relaxation therapy has also been applied to control essential hypertension. The definition of hypertension, according to the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC7),25 is systolic blood pressure greater than 139 mm Hg and diastolic blood pressure greater than 90 mm Hg. Prehypertension refers to systolic blood pressures between 130 and 139 mm Hg and diastolic pressures between 80 and 89 mm Hg. Standard treatment for established hypertension is antihypertensive medications, diet, and exercise. For patients in the prehypertensive blood pressure range, lifestyle changes are the primary intervention, unless the patient has multiple risk factors.25
Representative clinical evidence
Linden et al reported on the effects of 10 weeks of individualized psychophysiologic treatment on ambulatory blood pressure in patients with essential hypertension.26 Patients were initially screened for anxiety, depression, and anger, after which a program was designed for each patient based on his or her psychological risk factors. All patients received some form of relaxation therapy, and some received biofeedback. Over time significant reductions in ambulatory systolic and diastolic blood pressure were observed.26 In a separate study, Yucha et al provided a multimodal training program to hypertensive individuals and also reported significant decreases in blood pressure.27
Elliott et al trained hypertensive patients to use the RESPeRATE™ device to achieve the slow, deep breathing associated with the “relaxation response” sought in relaxation training.28 After initial training, patients were instructed to practice this device-guided breathing technique at home. Significant reductions in systolic blood pressure were observed over 8 weeks in the patients who used the device compared with controls who simply monitored their blood pressure at home. A maximum mean systolic blood pressure reduction of 15 mm Hg was achieved in the group of patients who practiced device-guided breathing for the greatest number of minutes during the 8-week study. Similar results with device-guided breathing using this device have been reported in two separate studies.29,30
More general stress reduction programs have also achieved success when offered to patients with essential hypertension in the clinic or the workplace. Studies of programs focusing on meditation and repeated practicing of centered breathing and relaxation responses, without use of biofeedback, have reported reductions of approximately 10.7 mm Hg in systolic pressure and 6.4 mm Hg in diastolic pressure.31,32 McCraty and colleagues provided a stress management program to hypertensive individuals at their place of work,33 based on the premise that individuals’ work demands are a source of chronic stress and thus create an ideal setting for the application of new coping skills. In this study, stress reduction training was associated with significant reductions both in blood pressure and in global measures of distress.33
Prehypertensive patients: An ideal target population
Although meta-analyses demonstrate that there is support for the efficacy of biofeedback in patients with essential hypertension,34,35 the field has been handicapped by the reality that most patients with hypertension are already being treated pharmacologically, which means that their blood pressure levels when starting biofeedback treatment are often low,36 limiting the potential effects of the intervention. The new category of patients with prehypertension may thus be the ideal population for stress management therapies, since their blood pressure is elevated, but not elevated enough to have prompted medication prescriptions in most cases. Lifestyle modifications, which could certainly include stress management, are the recommended first-line therapies for these prehypertensive patients.25
Possible mechanisms of biofeedback in hypertension
One can hypothesize on the mechanisms of action of relaxation-based therapies in hypertension. Relaxing the muscles of the face via electromyography biofeedback and increasing finger temperature facilitates whole-body relaxation and decreased sympathetic adrenergic activity. Parasympathetic dominance is facilitated by the use of breathing techniques to increase heart rate variability. 37,38 The improved deep sleep that results from relaxation may also reduce blood pressure by restoration of nighttime blood pressure dipping.16
IDENTIFYING THE BEST CANDIDATES IS NOT EASY
Some individuals are excellent candidates for biofeedback, while others do not benefit despite their best efforts.39,40 The likelihood of response is generally associated with adherence to medical recommendations and willingness and ability to follow instructions for home practice of relaxation. Nevertheless, some patients who attend sessions and practice still do not succeed, perhaps because they have few signs of overarousal in the system, such as a high degree of sympathetic activation, muscle tension, or low heart rate variability. Further, patients must be able to demonstrate that they learned the skill that was trained, such as consistent warming of the hands. If the training was for heart rate variability, the patient should be in the optimal range of heart rate variability and be able to demonstrate high-frequency waves.34 Patients with specific characteristics, such as stress sensitivity, may benefit more than those whose blood pressure and blood glucose are chronically elevated with few fluctuations.
CONCLUSIONS
The etiology of the metabolic syndrome is complex and multifactorial. Psychophysiologic interventions such as biofeedback and relaxation training are sometimes warranted for multiple aspects of metabolic syndrome, and they target several specific associated disruptions, particularly chronic stress, negative mood, and behavior. Initial patient evaluation should aim to assess the patient’s readiness for change, which must be present to a sufficient degree before continuing with biofeedback or relaxation techniques. Use of motivational interviewing techniques is recommended to increase patients’ preparedness for change.41 Understanding patients’ characteristic responses to stress will guide decisions on the type of biofeedback and relaxation therapies to use and whether or not psychotherapy will be necessary. Specific modalities of biofeedback or particular types of relaxation do not appear to be as critical as the total package of individualized psychophysiologic therapy.
