Research Review Finds Yoga Beneficial in Reducing Hypertension
Hypertension, or high blood pressure, remains the most common reason for office visits to physicians for non-pregnant adults in the United States. Some 50 million Americans are believed to have hypertension. Despite its prevalence and the complications associated with it, control of the disease is far from adequate. As a result, hypertension will likely remain the most common risk factor for stroke, heart failure, and kidney disease for years to come.
At the same time, some 42 percent of Americans have used complementary and alternative medicine (CAM) approaches to meet their health care needs, spending more out-of-pocket for CAM than the amount projected for expenditures in 1997 for all U.S. physician services. Nearly three million people are estimated to have tried mind-body techniques to treat their hypertension; approximately eight percent of the hypertensive population.
Mind-Body medicine, one of five major branches of CAM therapeutics, uses behavioral techniques to augment the mind’s capacity to affect bodily function and symptoms, utilizing varied approaches such as meditation, prayer, mental healing, and therapies that use creative outlets such as art, music, or dance. The 2002 National Health Interview Survey (NHIS) found nearly 30 million users of relaxation techniques including meditation and yoga, and 10 million users of yoga therapies. One-fourth of those who used mind-body therapies rated them “very helpful.”
There has been little quality research to discriminate between positive anecdotal evidence, marketing schemes, and practices that are consistently effective and safe. As a result, a team of researchers conducted a systematic review aims to assess the efficacy of mind-body therapies (MBT) versus placebo or active control in the treatment of hypertension. The main outcome measures include change in systolic and diastolic blood pressure pre- and post-intervention period.
The team reviewed randomized, or quasi-randomized, controlled trials comparing mind-body techniques (meditation, yoga, and guided imagery) alone or in combination with conventional treatment to conventional treatment alone or no intervention/waiting list control. Relevant trials were identified in the register of trials maintained by the Cochrane Complementary Medicine Field Registry, The Cochrane Central Register of Controlled Trials, Medline, EMBASE, PsycInfo, and CINAHL.
Mind-Body Therapies (MBTs)
Participants in these trials were men and non-pregnant women, greater than 18 years of age with hypertension defined as a systolic blood pressure of >140 mm Hg and/or diastolic blood pressure >90 mm Hg. (Normal is defined as systolic >140 and/or diastolic >90 mmHg). The types of intervention undertaken by the study participants were mind-body techniques with the greatest rates of utilization (>3.5 percent prevalence of use in the general population) being meditation, yoga, and guided imagery techniques. A description of each follows:
• Meditation: A systematic mental focus on particular aspects of inner or outer experience involving engaging in an activity that directs the mind to single point of focus, using breathing techniques, or imagery in order to feel a state of calmness.
- Yoga: The Sanskrit word yoga connotes “the joining of the lower human nature to the higher.” Yoga techniques comprise a series of body positions and movements developed in order to help relax the body and calm the mind. It involves breath control, physical exercises and meditation.
- Imagery: The generation (either by oneself or guided by a practitioner) of different mental images. Using the capacities of visualization and imagination, individuals evoke images, usually either sensory or affective. These images are typically visualized with the goal of evoking a psychophysiological state of relaxation or with some specific outcome in mind.
The review and synthesis of 12 published randomized trials found largely favorable effects of the most popular mind-body therapies on systolic and diastolic blood pressure. Mind-Body Therapies (MBT) significantly reduced systolic blood pressure (SBP) by a mean 11.52 mm Hg and diastolic blood pressure (DBP) by 6.83 mm Hg. Of the three MBT analyzed, yoga therapies demonstrated results of the greatest magnitude, with mean SBP reductions of 19.07 mm Hg and DBP by 13.13 mm Hg. Significant results were seen in SBP reductions by yoga and meditation therapy, while only yoga therapies demonstrated significant reductions in DBP.
The absolute reductions in blood pressure were comparable to pharmacologic monotherapy in both effect size and temporality. Additionally, reductions in systolic and diastolic blood pressure to the degree found in yoga interventions were associated with reductions in vascular death rates as well as decreased overall cardiac risk.
According to Dr. Ali, the lead author, “This review shows that there is some high quality scientific literature supporting the use of mind-body therapies as a treatment for hypertension, and the magnitude of effect is clinically significant.” Despite the limitations of a review, he suggests mind-body interventions may be prudent choices for adjunctive treatment for motivated patients.
The systematic review is entitled, “Mind-Body Practices for Hypertension: Systematic Review and Meta-Analysis.” The study was conducted by Ather Ali, ND, MPH and David L. Katz, MD, MPH, of the Prevention Research Center, School of Medicine, Yale University; and Michael B. Bracken, PhD, MPH, of the Department of Epidemiology and Public Health, Yale University, New Haven, CT. Dr. Ali is presenting his team’s findings at the 22nd annual meting of the American Association of Naturopathic Physicians (AANP; http://www.Naturopathic.org). The conference will be held at the Palm Springs Convention Center, Palm Springs, CA, August 22-25, 2007.
Source: American Association of Naturopathic Physicians (AANP)