Toronto researchers found that people who learned and applied the technique did not end up with lower blood pressure readings than people who did not use the approach.
Mindfulness-based stress reduction is a program that helps people learn about their relationship with their thoughts, emotions, behaviours and sensations.
The technique, which involves deep-breathing techniques also used in yoga, has been shown to be effective in helping to control anxiety and cancer-related pain.
Senior author Dr. Sheldon Tobe says he was surprised mindfulness did not result in lower blood pressure, because cognitive behavioural therapy has been shown to be useful in hypertension.
In fact, studies of cognitive behavioural therapy suggest it lowers blood pressure on average as well as a single hypertension drug at a starting dose would do.
"That's a good drop in blood pressure. And that kind of blood pressure drop will lead to a reduction in heart attack and stroke over time," said Tobe, a nephrologist (kidney specialist) at Sunnybrook Health Sciences Centre, a University of Toronto teaching hospital.
The study, by researchers from the University of Toronto and York University, was published recently in the American Journal of Hypertension.
Tobe admitted the research team expected mindfulness-based stress reduction, or MBSR, would be effective.
"It seemed very promising for us," said Tobe, whose work is funded by the Heart and Stroke Foundation of Ontario. "I was disappointed. I really thought it was going to work."
In the trial, 101 adults in the early stages of a blood pressure problem were randomly assigned to either take the eight-week mindfulness program or not. In addition to attending weekly classes on MBSR, participants had to do homework — practise the technique out of class. They also had to keep a log of their efforts.
Then, at 12 weeks after the start of the study, blood pressure readings from the participants were compared to their blood pressure from the start of the study. There were no differences between the two groups.
After the first round of the study, the group that hadn't initially taken the course was taught the technique and their blood pressure levels were measured after 12 weeks. That gave the researchers both before and after data, and gave them a larger pool of results to compare.
But there was still no difference, Tobe said. "As a stand-alone (treatment) for people who have high blood pressure, who are not yet on drug therapy, MBSR as a kind of ... therapy was not effective at blood pressure lowering."