Forty-three volunteers with high blood pressure completed the one-year trial. To measure the effects, the researchers gave their subjects questionnaires to gauge how well they identified and controlled their emotions as well as tests to assess their ability to pay attention to a task before the program began and again three months, six months and 12 months after it ended. The study also evaluated its subjects’ physical-activity level, diet, body mass index, perceived stress, alcohol consumption, medication adherence and blood pressure. Those who weren’t following official guidelines on heart health at the outset all showed improvements when it came to physical activity, diet and alcohol consumption; all participants reported lower stress. On average, a year later, the study participants had lowered their systolic blood pressure by six points and their diastolic pressure by an average of one point, a significant overall improvement.
But the study also illustrates the difficulties inherent in trying to judge the health effects of any psychological intervention. The scientific method, in comparison, is well suited to testing drugs like blood-pressure medications: One group of trial subjects gets the medication, another gets a placebo and neither the researchers nor the participants know who gets what until the clinical trial is over, eliminating the possibility that their expectations about the drug’s effectiveness influence the results. In other words, the conditions for each group are exactly the same, except for the chemical makeup of the pill they are ingesting. In theory, then, any difference in health outcomes between the groups must be a result of that difference in chemicals.
It is impossible, though, for persons practicing mindfulness not to know whether or not they are doing it, so how do you create a “placebo” for a control group? Loucks’s study compared participants with themselves before and after the mindfulness training, but it’s impossible to be certain whether the training itself caused the observed changes. It could be that simply meeting in a group for two hours a week (or 10 minutes a week, for that matter) improves health. To find out, you would need to convene such a gathering for the same length of time as the mindfulness training group and then “give them something to do,” Loucks says. “What is that content?” — taking a health class? — “and is it messing with our question?” To put it another way, can you say what the precise difference is between the mindfulness training and that health class, which is the behavioral equivalent of the chemical difference between a drug and its placebo, that accounts for a difference in outcomes?
That difference, the aspect of mindfulness that impacts health, may become clearer as researchers develop increasingly specific mindfulness-training programs and test them on larger, more diverse groups of people. In Loucks’s study, as in many mindfulness studies, most of the participants who responded to advertisements seeking volunteers were white, college-educated and by definition interested in trying the practice, so it’s not clear if the results apply more widely. Loucks is currently running a randomized trial of his mindfulness-based blood-pressure program with 200 volunteers; those in the control group work with a physician to manage their blood pressure and receive a blood-pressure monitor to keep at home along with training on its use, which has been shown to improve how well patients manage their condition. (Not having all the answers yet doesn’t mean we shouldn’t act; health officials approve many drugs without knowing for whom they will work best, at what dose and why, or what their long-term effects might be, variables that even the most rigorous trials can’t always determine.)