In the analysis, researchers examined data from more than 2,150 adults who took part in a community health clinic Mindful-Based Stress Reduction (MBSR) class between 2002 and 2016. MBSR is a standard 8-week mindfulness program typically taught in person that is offered widely in health care settings.
The team looked at pre- and post-test results on a common assessment of psychological symptoms and a measure of troublesome physical symptoms. They also included data from three National Institutes of Health-sponsored studies on MBSR that had people who were randomly assigned to control groups and compared harm in those studies with community MBSR. This allowed the group to examine results and levels of harm in people who did not take MBSR.
Because there is no standard way to assess harm, researchers looked at several common measures of harm, including whether average symptoms worsened, the number of people who reported increased symptoms, the number reporting greater than a 35 percent increase in symptoms and clinically significant harm, or the proportion of people who reported a categorical worsening in symptoms (e.g., from normal symptom level to mildly symptomatic).
The scientific team did not find a single instance in which harm that was experienced by people in MBSR (community or research) was greater than base rates of increased negative symptoms experienced by people in the control group that received no treatment.
In addition, on about half of the harm measures the researchers examined, rates of harm in MBSR were significantly lower than those in the no-treatment group. Hirshberg notes that these findings “suggest that MBSR may not only be no more harmful than no treatment, it may actually be preventative of developing increased psychological and physical symptoms.”
The researchers were careful to note, however, that more research of potential preventative effects is needed because most preventative effects were observed in comparisons between community MBSR and people in the research MBSR studies who received no treatment – groups that had significantly different levels of symptoms at baseline.