Some of the most convincing scientific evidence for the stressreducing effect of nondirective meditation is a modest lowering of blood pressure.
It is an interesting physiological marker of stress reduction because it is closely associated with changes in the autonomic nervous system, and because it is easy to measure. Changes in blood pressure have important health effects. Elevated levels are one of the main causes of serious diseases like heart attacks, stroke, and dementia. Experts agree that even a modest reduction in blood pressure over time improves health and longevity. This chapter explains the science of nondirective meditation and blood pressure: how it advanced from early observations to more sophisticated studies, how the effect of nondirective meditation compares with directive methods, and preliminary evidence of long-term, associated health effects.
Blood pressure reduction is one of the best documented indications that nondirective meditation reduces stress. A regular practice is associated with a modest blood pressure reduction—not during all sittings, nor in all meditators, but in sufficiently many that a statistically significant reduction is detected when it is measured under standardized conditions in everyday life, outside the meditation breaks. The first two studies on nondirective meditation and blood pressure were published in 1974 (Benson et al., 1974a; 1974b). Dr. Herbert Benson and colleagues followed people with blood pressure measurements just above the range of normal limits (borderline hypertension, see text box on next page) in several visits to the clinic.
The medical term hypertension refers to chronically elevated blood pressure. At the time when Benson’s study was undertaken, borderline hypertension referred to stable blood pressure measurements just above the upper “normal” limit of 140/90 mmHg, when repeated in several visits to a clinic. For many years, 140/90 mmHg defined the starting point for taking blood pressure medicine. Current guidelines are stricter in the presence of other risk factors, such as smoking, high cholesterol, stroke, diabetes, and cardiovascular or kidney disease.
The formula “140/90 mmHg” is the standard way to describe an upper (systolic) blood pressure of 140 and a lower (diastolic) blood pressure of 90 mmHg. The abbreviation “mmHg” means millimeters of mercury, the unit by which blood pressure is measured. This somewhat peculiar unit stems from the time when pressures were measured by reading the height of liquid mercury in a glass tube connected to the cuff around the upper arm.
An average change of 5–10 mmHg appears to be a very modest reduction in blood pressure. However, responses are individual, reflecting the fact that some people have greater reduction and can minimize or stop taking medicine, whereas others have lesser reduction or no change. This is the also case with blood pressure medicine; therefore, follow-up has to be personalized, depending on response. Some recent studies suggest that there are beneficial effects of lowering blood pressure down toward 120/80, especially in regard to the development of dementia. In some individuals, even a small reduction can make a difference for health over many years.
After 20–25 weeks of regular practice of the nondirective technique Transcendental Meditation, the participants’ blood pressure had stabilized at a lower level within the normal range, on average about 5–10 mmHg below measurements before the intervention. The first study included people not using any drugs to lower blood pressure; the second involved patients on blood pressure medicine. These results suggested that nondirective meditation might be used for those who are willing to try stress reduction and only need a modest effect in order to avoid or reduce blood pressure medicine. Even more importantly, the studies suggested that meditation over time led to lower levels of stress in everyday life, outside the meditation breaks—using blood pressure as a marker of changes in autonomous nerve activity.
Even though the findings of the first studies were promising, it could be argued that blood pressure reduction might be unrelated to meditation and better stress management. An alternative explanation could be that the effect was due to positive expectations of the treatment—a placebo effect—or simply that blood pressure would have normalized over time regardless. This view was challenged by a study of 126 volunteers from corporate offices of a manufacturing firm, all of them with normal blood pressure (Peters, 1977a; 1977b). Participants were randomly divided into three groups. Group A practiced the Relaxation Response, a nondirective meditation technique, 10–15 minutes twice a day. Participants in group B spent the same amount of time just sitting quietly and relaxing. Group C was a control group of employees that received no stress management instructions.
All participants had their blood pressure measured twice a week and responded regularly to questionnaires regarding five topics: (1) physical and mental symptoms, (2) wellness and illness, (3) their own perception of work performance (energy, concentration, problem solving, efficiency), (4) social satisfaction, and (5) happiness/ unhappiness. After eight weeks, the first four items had improved significantly more in those who practiced nondirective meditation, compared to those in the control group. Just relaxing yielded intermediate results. Two sessions per day seemed more than necessary to obtain a positive effect, whereas no change occurred with fewer than three sessions per week.
Blood pressure changes followed a pattern similar to the measures of wellness and performance. A significant reduction (11.6/7.9 mmHg) occurred with meditation, modest lowering (6.5/3.1 mmHg) came with relaxation, and no change occurred in the control group. These results showed that nondirective meditation was more effective in lowering blood pressure than just relaxing or being observed over time in a control group. They also suggested that spending time on regular stress reduction improved self-reported health and wellness. The blood pressure reduction was similar to that of other well-documented changes in lifestyle, such as reducing the amount of salt in the diet or taking up regular physical exercise. Although more advanced studies have been undertaken during the following decades, the evidence remains insufficient to establish meditation as a treatment for high blood pressure. Nevertheless, it has been accepted by the American Heart Association as an addition to standard medical therapy, because of its low risk and low cost (Brook et al., 2013; Levine et al., 2017). As described in the next sections, both blood pressure reduction and symptom reduction indicate that nondirective meditation reduces stress in normal working populations.
A limitation of the corporate office worker study was the control activity of the relaxation group. Participants were told that as long as they sat quietly without speaking and did not focus on any repetitive thought, they could daydream, think about their days, listen to music, or use the time for any similar relaxing activity. Although this instruction gave participants total freedom and no pressure to perform, it could be argued that the lack of a specific technique would be less likely to evoke confidence and positive expectations, and therefore be a less potent means by which to induce a positive placebo effect on blood pressure. Hence, Progressive Muscle Relaxation has been used in several studies as an active comparator of nondirective meditation. It is well suited for several reasons: the technique is clearly described and can easily be standardized, it has been considered an effective relaxation technique for several decades, and it has a bodily focus, in contrast to the mentally repeated meditation sound. It is also practiced in a concentrated manner, with the attention directed toward the specific goal of systematically tensing and then relaxing the muscles, in contrast to the free mental attitude of nondirective meditation.
One of the first studies comparing blood pressure in nondirective meditation with an active control group was performed in Stockholm in 1991–1992 by Dr. Pär Westlund and colleagues (1993; 2008). They studied 80 Swedish locomotive engineers who had no previous diagnosis of hypertension (high blood pressure). Forty had responded positively to an invitation to a course in stress reduction and were randomly assigned to eight weekly meetings of instruction in either the nondirective technique Acem Meditation or the directive technique Progressive Muscle Relaxation, with monthly follow-up meetings for six months. They were advised to practice 20–30 minutes two times per day. The passive control group was comprised of forty locomotive engineers with a similar background (age, gender, years as locomotive engineers), who had not volunteered for the course, and who were simply asked to come for baseline examinations before the intervention and follow-up testing after six months.
In a previous study of their working environment, 80 percent reported some form of sleep disturbance because of working irregular hours and night shifts. This also affected the quality of their leisure time. They described some of their problems as “lack of energy,” “walking in a haze,” or “feeling like a zombie.”
Both relaxation groups improved their measures of sleep quality, health-related quality of life, and psychological symptoms, compared to the control group, most markedly with Acem Meditation. Blood pressure was within normal limits in all three groups prior to the intervention, and fell significantly only with Acem Meditation (5.0/4.2 mmHg reduction). Participants in both intervention groups reported that they felt better if they practiced briefly during a break in their night shifts. There was a slight difference between methods. Participants who used Progressive Muscle Relaxation felt more energetic, while those who used Acem Meditation felt calmer and more rested. At the final follow-up, 62 percent of the participants in the Progressive Muscle Relaxation group reported that they practiced 1–5 times per week, and 38 percent said that they practiced 6–9 times per week. The corresponding numbers for Acem Meditation were 63 and 37 percent, respectively. Despite some limitations in the design of the study, these results indicated that nondirective meditation has a more marked effect on the bodily manifestations of stress than does an active, concentrative technique directed at muscle relaxation.
Two studies of African Americans with borderline to moderately elevated blood pressure indicate that nondirective meditation is more effective than directed muscle relaxation (Schneider et al., 1995; 2005a). In this population, blood pressure is known to be associated with psycho-social stress. The first study followed 127 elderly people from the Oakland area in California for three months, and found that the nondirective technique Transcendental Meditation resulted in a greater blood pressure reduction than did Progressive Muscle Relaxation. The changes were 10.7/6.4 mmHg versus 4.7/3.3, respectively, whereas no change occurred in a control group that had a similar amount of instruction in lifestyle modification. Participants in the control group were encouraged to follow specific guidelines on dietary salt, caloric intake, and aerobic exercise, with the expectation that it would lower blood pressure.
The second study found the same pattern of blood pressure reduction when 150 middle-aged men and women from the same area were followed for a year. Nondirective meditation was more effective than actively directed muscle relaxation, and health education showed little effect. However, the extent of blood pressure reduction was less in both groups, 3.1/5.7 mmHg with nondirective meditation versus 0.5/2.9 with relaxation. The reason for this was probably that blood pressure in the first study was higher at the outset, possibly reflecting a higher level of stress. In the first study, blood pressure was 179/104 mm Hg, versus 142/95 in the second. This is much closer to normal blood pressure, indicating that the potential for reduction may have been more limited.
Altogether, the studies on the Relaxation Response, Acem Meditation, and Transcendental Meditation show that a regular practice of nondirective meditation over time leads to moderate blood pressure reduction. The effects of nondirective meditation were greater than those of directed stress reduction by Progressive Muscle Relaxation and those of other relevant control interventions. These findings are important because they give a strong indication that nondirective meditation has a specific effect on the stress level expressed in our bodies, beyond that of voluntarily directed muscle relaxation, positive expectations, receiving social attention, or spending time together for health education. In several studies, the amount of blood pressure reduction was associated with the extent of improvement in a number of mental and physical symptoms of stress. Hence, the accumulated results support the idea that blood pressure lowering could serve as a biomarker of bodily and mental stress reduction.
Blood pressure is an interesting marker of stress and relaxation because it is easy to measure, and because its long-term effects on health and longevity are well documented. High blood pressure—or hypertension—is often called “the silent killer.” Unless it is severe, its symptoms are usually completely absent or nonspecific, such as headache, tiredness, and loss of energy. Moreover, hypertension is one of the most important risk factors for cardiovascular disease, which over time can lead to heart attack, stroke, dementia, and eventually premature death. In concert with other major risk factors, such as high cholesterol, smoking, diabetes, and lack of exercise, hypertension leads to cholesterol deposits, a narrowing of the vessel walls, and a reduction of the blood supply to the heart, brain, and other vital organs. There is solid evidence that interventions that reduce blood pressure, even within normal levels, can prevent the fatal consequences of hypertension. Taking blood pressure lowering medicines is a very successful example (see text box on page 73).
A small study suggests that nondirective meditation may mitigate the narrowing of the large artery of the neck, the carotid artery (Castillo-Richmond et al., 2000). This is one of the main vessels that supply the brain with blood. It is often examined as an indicator of cholesterol deposits in the wall of other arteries of the body, because it is easily accessible for noninvasive measurements by ultrasound.
In this study, the thickness of the carotid artery wall was measured in 60 African American women and men from the Los Angeles area before and after an intervention of either the nondirective technique Transcendental Meditation or a similar amount of instruction and follow-up of health education. After six to nine months, the carotid wall thickness of the meditation group tended to go down, whereas it tended to increase in the control group, even though the changes in blood pressure and other risk factors were similar in both groups. Although these results suggest that nondirective meditation mitigates thickening of the vessel wall, larger and more extensive studies are needed to determine whether such preliminary findings translate into long-term health benefits.
One of the first indications that stress reduction by nondirective meditation may influence long-term health outcomes was published in a report on elderly white retirement home residents from Massachusetts (Alexander et al., 1989). A study with a focus on cognitive functions and mental health also recorded how long participants lived after they had engaged with different mental techniques. The participants, 73 men and women with a mean age of 81 years, were randomly assigned to either: (1) the nondirective technique Transcendental Meditation, (2) concentrated attention by creative word production, (3) mental relaxation by silently repeating brief comfortable words or phrases of the participants’ own choice, or (4) a control group that received no specific instruction, but got the same amount of mental testing and other assessments. The group with nondirective meditation improved most on associative learning, cognitive and behavioral flexibility, mental health, aging, and blood pressure, compared to the control group, followed by the concentrative attention training group, which performed slightly better on perceived control and word fluency. After three years, the percentage of residents that was still alive was greater with nondirective meditation, followed by concentrative attention training, both when compared to the control group, and compared to the nonparticipating residents from the same retirement homes.
Since the number of participants was too small for strict longevity assessments by statistical survival analysis, data from this study was combined with observations from the blood pressure study of elderly African Americans in Oakland (Schneider et al., 1995). Altogether, the survival analysis of the combined 202 participants showed a 23 percent reduced mortality rate with the nondirective technique Transcendental Meditation after a mean observation time of 7.6 years, compared to the combination of the active and passive control groups (Schneider et al., 2005b). The increased longevity in the meditation group was due to fewer cardiovascular and cancer deaths. Even though numbers were small and control groups were different, these results support the idea that nondirective meditation not only gives a mild reduction in blood pressure and stress-related symptoms, but also seems to affect health positively over time.
It is interesting to note that nondirective meditation may have a preventive health effect, even in old age. As will be described in chapter 6, one of the psychological effects of nondirective meditation is a reduced load of depressive symptoms and signs. It is well known that depression is an important risk factor for cardiovascular disease and mortality, especially in the middle-aged and elderly. It is therefore tempting to speculate that the psychological effects of meditation could play a role in disease prevention, in addition to a change in autonomic nerve activity and blood pressure reduction.
Scientists who study disease in large populations agree that even modest reductions in blood pressure, mental stress, and other risk factors over time improve health and longevity. The challenge of providing scientific proof that disease prevention actually works is the large numbers and the length of time required when participants are young and healthy at the outset. It is easier to prove that meditation works in those who have a high risk of health problems in their near future.
The effectiveness of nondirective meditation in preventing serious cardiovascular events has been evaluated in a clinical trial at the Medical College of Wisconsin (Schneider et al., 2012). The participants were 201 middle-aged African American men and women who already had signs of coronary artery disease. In this population, hypertension and psychosocial stress are important risk factors for cardiovascular disease, which is associated with a high risk of heart attack, stroke, and death from all causes. Half of the participants were randomly assigned to a program of practicing nondirective meditation for 20 minutes two times per day, in addition to usual medical care.
After a seven-step course in the nondirective technique Transcendental Meditation, participants were followed up by a certified instructor in weekly maintenance meetings for the first month, bi-weekly for the following two months, and then monthly. The control group participated in a cardiovascular health education program designed to match the format of the meditation intervention for instructional time, instructor attention, participant expectancy, social support, and other nonspecific factors that might favorably affect the reported outcome of the study. The participants in the health education group were asked to spend at least 20 minutes per day at home practicing heart-healthy activities, such as exercise, healthy meal preparation, and taking relaxation breaks.
During an average follow-up period of 5.4 years, there were 48 percent fewer incidents of serious cardiovascular events such as heart attack, stroke, and death from all causes in the meditation group, compared with health education. There were also trends for lower blood pressure, reduced psychological stress, less expression of anger, and other positive health outcomes. Although the study was small and had some other limitations, the researchers concluded that stress reduction by a meditation program may be useful in preventing cardiovascular disease.
The studies discussed in this chapter indicate that nondirective meditation over time leads to a modest reduction in blood pressure. A closer look at the evidence showed that regular practice has a specific effect, beyond that of voluntarily directed muscle relaxation, positive expectations, receiving social attention, or spending time together for health education. The minimal or optimal “dose” has not been and probably will not be determined by controlled scientific experiments. Most studies recommended two 20 to 30-minute sessions per day. Solid results were achieved in those who practiced most days of the week, while three sessions per week seemed less than optimal. In several studies, measures of other bodily and mental stress symptoms were reduced in parallel with the blood pressure, supporting the idea that blood pressure lowering could serve as a general biomarker of stress reduction.
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