Getting the drop on blood pressure.

Getting the drop on blood pressure

Several recent studies have suggestedthat muscle-relaxation training and biofeedback techniques that promote relaxation reduce the blood pressures of some hypertensives. But scientists at SRI International, a nonprofit research organization in Menlo Park, Calif., now report that there is a simpler alternative for newly diagnosed mild hypertensives: no relaxation training, no medication, just regular blood pressure monitoring for at least one year.

"We were surprised by the results,"says project director Margaret A. Chesney. "It appears that before physicians make decisions about medications or other treatments for mild hypertensives, the first step might be systematic blood pressure monitoring."

The researchers recruited unmedicatedpersons with mild hypertension, whose diastolic blood pressure (when the heart expands) ranged from 90 to 104 mm Hg, from two large companies near San Francisco. They randomly assigned 40 mild hypertensives to blood pressure monitoring every nine weeks at both a company medical clinic and each participat's worksite. Another 118 hypertensives received 13 weekly instruction sessions in a behavioral treatment, either muscle-relaxation procedures alone or in combination with biofeedback measures of muscle relaxation, "cognitive restructuring" aimed at identifying stressful situations and thoughts, and advice on exercise and dietary changes.

In company clinics, significant bloodpressure reductions for both behavioral treatment and monitoring groups appeared after 18 weeks, report Chesney and her co-workers in the May/June PSYCHOSOMATIC MEDICINE. Systolic blood pressure (when the heart contracts) fell an average of 7.4 mm Hg for those receiving behavioral treatment and 9.0 mm Hg for subjects being monitored. Diastolic blood pressure declined an average of 4.5 mm Hg for the former group and 5.9 mm Hg for the latter group. These reductions remained 36 weeks later.

Both groups also displayed significantblood pressure reductions at the worksite by the end of the year-long study.

Reasons for the equal effectiveness ofbehavioral treatments and blood pressure monitoring are unclear, says Chesney. the percentage of individuals whose personal physicians prescribed antihypertensive medication during treatment did not differ between the two conditions, and neither group showed significant changes in weight. These factors, notes Chesney, are unlikely to have accounted for the results.

But there are several possible explanations. "Whenblood pressure is repeatedly measured," she says, "there may be a desensitization to anxiety that often elevates the blood pressures of mild hypertensives in clinic settings." Expectations that blood pressure will drop as a result of monitoring may also be critical. Furthermore, monitoring may serve as a form of biofeedback, since participants see their blood pressure readings at each measurement session.

"We need to study more closely whatrepeated blood pressure measurements do to the sense of control over one's body," says Chesney.

Relaxation training has useful short-termeffects, however, on hypertensives whose blood pressures are not controlled by medications, report W. Stewart Agras of Stanford University School of Medicine and his colleagues in the same PSYCHOSOMATIC MEDICINE. They identified 137 such individuals in the sample screened by the SRI scientists and assigned them either to relaxation training or blood pressure monitoring. The proportion of those whose blood pressure came under control was markedly greater in the relaxation group up to a two-year follow-up. At a 30-month follow-up, there was no significant difference between the groups.