Behavioral Treatment of Hypertension

Patients are always looking for a treatment for hypertension that does not include a lifetime of taking drugs, and since there is a common perception that hypertension is one of the results of the stress we all live under these days, techniques that lead to stress reduction might be expected to lower blood pressure. Although such procedures as autogenic training and progressive muscle relaxation have existed for more than 50 years, the concept exploded in the early 70s with the popularization of two forms of treatment, one ancient and the other novel: transcendental meditation and biofeedback. The former was championed by Dr. Herbert Benson in Boston, ¹ and the latter by Dr. Chandra Patel in the U.K. ² , ³ Both groups published some dramatic results indicating that these behavioral treatments could provide decreases in blood pressure of the same magnitude as seen with drug treatment, without the expense and side effects of drugs. One of Dr. Patel's studies ⁴ involved 116 patients who were trained in relaxation and biofeedback and, at 1 year, had reductions in blood pressure of 12/4.1 mm Hg relative to a control group. Benson et al. ⁵ reported a fall of 10.5/4.9 mm Hg in patients on antihypertensive drugs who practiced the relaxation response regularly. Thirty years later, neither procedure has an established place in the routine treatment of hypertension, although both are used for other purposes. So, what happened?

The idea of biofeedback originated with the work of Dr. Neal Miller, a renowned experimental psychologist, who first developed the concept of “visceral learning.” ⁶ It was based on a series of animal experiments showing that rats could be trained to raise and lower their blood pressure using psychological conditioning techniques. This finding was translated into human studies in which subjects were instructed to learn voluntary blood pressure control by attempting to sustain a tone, which was triggered by changes in blood pressure in the appropriate direction. The rationale was that one reason we cannot voluntarily control our autonomic functions is that we lack conscious perception of them, and that if this is provided (by biofeedback) we can learn to “drive our own bodies,” as one early enthusiast phrased it. While the concept was attractive and was supported by some positive early results, it has not stood the test of time.

One issue is the type of blood pressure measurements by which the effects of the interventions were judged. The early trials used clinic measurements, ² , ⁴ , ⁵ which are known to be very susceptible to the placebo effect. It is now clearly recognized that blood pressure tends to increase just before a clinic visit (the “white coat” effect), which has been attributed to the anxiety associated with the visit. Therefore, any intervention that reduces anxiety may lower the clinic blood pressure, without necessarily affecting the pressure at other times.

One of the most dramatic demonstrations of the power of the placebo and the effectiveness of reassurance was provided by an ingenious experiment designed by Dr. William Goldring and his colleagues, the results of which were published in 1956. ⁷ They made an impressive‐looking device, which they called “the electron gun.” It consisted of a large, metal coil surmounted by a conical “gun,” and an oscilloscope. The patient was seated in a darkened room, with the gun pointing at his or her chest. When the apparatus was turned on, the nozzle of the gun began to glow as if it were red‐hot, and to emit sparks and crackling sounds. At the same time, a series of sinusoidal waves was displayed on the oscilloscope. The treatment was carried out by a sympathetic nurse twice a week for several months, and then discontinued. In about one half of the patients with very high pressures, the blood pressure decreased during the treatment period, with an average drop of 36/27 mm Hg—a very impressive change. In addition, all of the patients reported an improvement in their symptoms, and several were able to return to work. However, once the treatment was discontinued, the pressure gradually climbed back to pretreatment levels.

Another problem with the meditation and biofeedback studies was that other investigators were unable to replicate the dramatic early results. Some of the individual studies were quite small, which limits their generalizability, and this led the National Heart, Lung, and Blood Institute to form a Hypertension Intervention Pooling Project, ⁸ which collected data from 733 patients in nine randomized studies, all of which used various types of biofeedback or relaxation training. The results, published in 1983, were disappointing: there was no effect of the interventions in treated patients, and in untreated patients there was a modest reduction in diastolic pressure, but no change in systolic. Ten years later, in 1993, another blow was inflicted on these behavioral forms of treatment by a meta‐analysis performed by Eisenberg et al. ⁹ The authors reviewed 857 studies that had involved a variety of behavioral techniques, including biofeedback, relaxation, and stress management, and identified only 26 that satisfied the selection criteria for scientific rigor. The results, while generally negative, were of interest. In studies in which only a single day's readings were used to measure the baseline pressure and the effects of the intervention were compared with data from wait‐listed controls, an average reduction of 13.4/9.0 mm Hg was achieved relative to the controls. Studies with a longer baseline period achieved a smaller reduction (4.1/4.0 mm Hg), and those with a placebo‐treated control group demonstrated no net reduction in blood pressure. One interpretation of this analysis is that the positive results reported for the behavioral interventions may have been attributable to regression to the mean and the placebo effect. However, most of the studies had sample sizes that may have been too small to demonstrate a significant difference between groups.

It can be argued that it does not matter whether the reduction in blood pressure is due to treatment or due to a placebo effect, since any reduction is therapeutic. The important issue is whether the intervention sustains the reduction over 24 hours, as opposed to merely lowering the clinic pressure (diminishing the white coat effect). The solution to the placebo question is to use 24‐hour ambulatory monitoring, which is the ultimate determinant of therapeutic efficacy. Any intervention that lowers blood pressure throughout the day and night can be regarded as therapeutically effective, while one that merely lowers the clinic pressure is ineffective. In general, placebos have been found to lower clinic pressure but not 24‐hour pressure. Most studies of biofeedback and relaxation used clinic pressure, but the reports of some early studies claimed a reduction in ambulatory pressure. ¹⁰ A later study by van Montfrans et al. ¹¹ showed a modest reduction in clinic pressure (2 mm Hg) but no change in intra‐arterial 24‐hour pressure. In a study of 39 subjects randomized to either a meditation group or a cognitive stress education control group, Wenneberg et al. ¹² reported a net reduction of 9 mm Hg in ambulatory diastolic pressure in the meditation group. ¹² This issue thus remains unresolved.

A novel approach was implemented by Henderson et al., ¹³ who developed a blood pressure biofeedback technique using a device that continuously monitors finger blood pressure. One of the attractive features of this method is that it is possible to give false feedback, so that the placebo effect can be eliminated. Subjects receiving true feedback can be trained to raise and lower their blood pressure by attempting to move a line on a computer screen whose position is determined by the blood pressure. This can be done in the home, and it was demonstrated that people can learn to improve their ability to lower blood pressure with practice, but this ability was not associated with any change in clinic pressure.

The changing fortunes of behavioral forms of treatment have been reflected in the Joint National Committee (JNC) recommendations over the years. In 1980 the committee concluded that “…these methods are still experimental and cannot yet be recommended for sustained control of hypertension.” ¹⁴ The 1984 report ¹⁵ was more optimistic: “Various relaxation and biofeedback therapies may consistently produce modest but significant blood pressure reduction [and they] should be considered in the context of a comprehensive treatment program that may include both pharmacologic and nonpharmacologic therapeutic approaches.” In 1988 the pendulum had begun to swing the other way: “These promising methods have yet to be subjected to rigorous clinical trial evaluation and should not be considered as definitive treatment for patients with high blood pressure.” ¹⁶ The latest report ¹⁷ (the sixth, published in 1997) stated: “Relaxation therapies and biofeedback have been studied in multiple controlled trials with little effect beyond that seen in control groups…the available literature does not support the use of relaxation therapies for definitive therapy or prevention of hypertension.”

Although behavioral forms of treatment are currently out of fashion for the treatment of hypertension, it is facile and simplistic to dismiss the many positive results of individual studies as merely placebo effects. Also, there are encouraging preliminary reports indicating that controlled breathing with use of a biofeedback device may lower ambulatory blood pressure. The last word on behavioral therapy has not yet been written.