There are nearly 700 published experimental trials assessing meditation-based interventions. Most of the research examines the efficacy of MBSR programs, but there are also studies of MBCT, other MBSR-derived programs, and shorter mindfulness interventions. Two meta-analyses of MBSR show average effect sizes of 0.5–0.6. The most comprehensive meta-analysis found mindfulness-based treatments to be especially effective for reducing symptoms of anxiety, depression, and stress. The majority of research has been in mindfulness-based interventions, outlined below.
A. Cancer-Related Symptoms
There are more than 60 clinical trials of mindfulness meditation in patients with cancer. More than two dozen studies that measured psychological variables have all shown significant improvements in a variety of outcomes such as mood disturbance, anxiety, stress, and quality of life. Three meta-analyses and a 2017 systematic review corroborate the beneficial mental health effect of mind-body therapies in cancer patients. From this review's conclusion, these therapies show efficacy in treating common cancer-related side effects, including nausea and vomiting, pain, fatigue, anxiety, and depressive symptoms, and improving overall quality of life. In addition, some studies have shown effects on biomarkers such as immune function and stress hormones. In summary, research supports the role of mind-body therapies for dealing with common experiences that cause distress around cancer diagnosis, treatment, and survivorship including loss of control, uncertainty about the future, fears of recurrence, and a range of physical and psychological symptoms. Growing research also supports their cost-effectiveness. Finally, online and mobile adaptations currently being developed and evaluated increase promise for use in a global context. Ultimately, while more carefully designed studies need to be done, there is enough promise in the utility of these modalities as an adjunctive part of cancer care.
In the past 5 years, there have been over a hundred clinical trials that examined mind-body therapies in the treatment of primary depression, or depression in the context of another major medical illness. Ten studies, seven of which were randomized controlled trials, specifically examined the effect of MBCT on patients with major depression. Several of these trials specifically looked at relapses of depression; they demonstrated a reduction of almost 50% in relapses in patients with a prior history of more than two relapses. One study compared MBCT to standard CBT and found the two modalities to be equally effective in treatment of recurrent depression. MBCT is recommended as a treatment for recurrent depression in the United Kingdom's National Institute for Clinical Guidelines.
One randomized controlled trial of 74 patients looked at the effect of brief mindfulness-based intervention on recurrent depression; this study demonstrated significant improvements in multiple outcomes compared to a psychoeducational control. Multiple other MBSR studies show improvement in mood in various populations, including military personnel with depression or posttraumatic stress disorder (PTSD).
C. Anxiety and Stress Disorders
There have been number of randomized controlled trials that have shown benefit in anxiety and stress disorders. A controlled trial of patients with generalized anxiety disorder or panic disorder, all of whom were receiving pharmacotherapy, compared MBCT to an anxiety education program and found MBCT superior for relieving anxiety and depression symptoms. A 2013 randomized controlled trial of MBSR in 93 patients with generalized anxiety disorder showed improved anxiety symptoms. A randomized controlled trial of 31 pregnant women showed reduction of anxiety and perceived stress and an improvement in mood. Other study populations where randomized controlled trials have shown the effectiveness of mindfulness to diminish anxiety include patients with obsessive-compulsive disorder, with intellectual disabilities, with implanted cardiac defibrillators, and with coronary artery disease. A randomized controlled trial studying patients with social anxiety disorder categorized patients into three groups: mindfulness, CBT, and control; results showed that the mindfulness-based intervention group and CBT group were both superior to the control group but equal to each other. Four controlled studies have been published on PTSD; two showed clear benefit for PTSD symptoms, one showed mixed results, and one showed benefit in mood. Finally, a 2014 systematic review of 17 MBSR studies published since 2008 concluded that MBSR is an effective modality for stress management in otherwise healthy individuals.
A 2013 systematic review and meta-analysis of MBSR for fibromyalgia identified six trials totaling 674 patients and concluded that there is favorable though low-quality evidence supporting its use and that “only a weak recommendation can be made at this point.” Two 2013 studies of an online mindfulness intervention for fibromyalgia, showed improved social functioning, positive affect, and coping with pain and stress. A 2017 randomized controlled trial of 74 patients with fibromyalgia found significant improvements in pain, sleep quality, and psychological distress with an 8-week mindfulness-based intervention.
There have been over 30 studies that have examined meditation-based intervention in chronic pain populations. The majority of studies showed significant improvement in mental health parameters, such as quality of life, acceptance, pain tolerance, and mood. A 2018 meta-analysis and systematic review of 13 studies concluded that mindfulness meditation has prominent effects on the psychological aspects on living with chronic pain, improving associated depression and quality of life. One follow-up study showed that improvements were maintained up to 4 years later. A randomized controlled trial of MBSR for patients with rheumatoid arthritis showed improvement in psychological distress and well-being at 6-month follow-up despite no improvement in disease activity. A second randomized controlled study of patients with rheumatoid arthritis compared a mindfulness-based intervention (that was much less intensive than standard MBSR) with a CBT intervention and an education control group. Both experimental groups were significantly superior to the control group, although overall the CBT group showed the greatest reduction in pain and interleukin-6 levels. In the subset of patients with a history of recurrent depression, however, the mindfulness-based intervention yielded greatest reduction in pain and improvement in mood. Benefit of mindfulness meditation was demonstrated in two randomized controlled trials in patients with headache, one in 2013 and one in 2014. A 2016 randomized controlled trial comparing MBSR to CBT in 342 people with chronic low back pain found that MBSR or CBT, compared with usual care, both resulted in significant improvement in back pain and functional limitations at 26 weeks, with no significant differences in outcomes between MBSR and CBT. Study authors concluded that MBSR is an effective treatment option for patients with chronic low back pain.
Other studies have been conducted involving patients with chronic insomnia, psoriasis, tinnitus, irritable bowel syndrome, inflammatory arthritis, type 2 diabetes mellitus, organ transplants, eating disorders, hot flashes, and female sexual arousal disorder, as well as with inner city residents, nursing home residents, incarcerated individuals, smokers, physicians, nurses and nursing students, medical students, and college students. Nearly all of these studies showed a mental health benefit from meditation, and most showed symptom reduction of the condition being studied. Interestingly, a randomized controlled trial of psychotherapists in training showed improvement in the patients of those therapists who were taught mindfulness, and a multicenter study of physicians showed greater patient satisfaction with physicians who had higher mindfulness scores.
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