The Evidence for Meditation

As you may know in a past life I was a medical doctor. And I am a meditator.  I’ve written previously about my own personal experiences with meditation, but I want to share here some cold hard scientific evidence for (and maybe against?) meditation, since these days medicine is all about the evidence.

I’ve reviewed A LOT of the research on meditation (particularly mindfulness meditation) to date.  I used a combination of Google Scholar searches and Pubmed searches to find studies. In particular I looked for meta-analyses, systematic reviews and randomized controlled trials, which are the strongest levels of evidence (not all “studies” are created equal). Also, the specific studies that I’m including below are mainly from highly reputable medical journals (again, not all “journals” are created equal, and since I’m not a scientific or statistical whizz I’m also relying that the editors of the journal have done a good job of weeding out questionable research).

You can read the Cliff’s Notes of the studies below as well as review the original literature, if you are so inclined.

For those of you who aren’t, here is a really quick summary of all the evidence to date:

(1) Meditation seems to have a relatively strong effect on emotional / psychological well being, especially related to improving feelings of stress, anxiety & depression (even as effective if not more so than anti-depressants and cognitive behavioural therapy?!).

(2) There might be some effect on cognitive functioning (for example, memory).

(2) Might increase positive emotion (not 100% clear).

(3) Some effect on physiological outcomes?  Doesn’t really effect pain itself, but can effect acceptance of pain and functioning with pain.

There is also some evidence that the benefits of meditation can be sustained (which I imagine would be significantly enhanced if the practice of meditation is continued beyond a one-time course or intervention) and surprisingly that even novice meditators can see significant effects, including potentially changes in the brain itself!

The psychological effects of meditation: A meta-analysis.

• Medium-Large effect of meditation on emotional & relationship issues.
• Medium effect on attention.
• Small-Medium effect on cognition.
• Interestingly, the experience level of the meditator had little impact on the results.

Fine Print:  Published in “Psychological Bulletin”, Reviewed 163 studies (excluded 432 studies), looked at healthy adults.

Meditation Programs for Psychological Stress and Well-being: A Systematic Review and Meta-analysis

• Moderate effect on improved anxiety.
• Moderate effect on improved depression*
• Moderate effect on improved pain.
• Low or No evidence for effect on positive emotion & attention.

*Interesting side note: from doing quick journal research related to the effectiveness of anti-depressant medication, up to 70% of the “effect” of the drug can be due to placebo (backed up by multiple meta-analyses). And even more crazily, a meta-analysis of anti-depressants vs placebo found that anti-depressants for mild to moderate and even severe depression fell below the threshold definition for a “small effect”! (Anti-depressants showed a small to moderate effect on patients in the “very severe depression” group).

I’m not an expert at statistics, but this evidence would seem to show that for depression defined as mild to severe meditation is MORE EFFECTIVE than anti-depressants! Put that in your pipe and smoke it!

Fine Print:  Published in “The Journal of the American Medical Association / Internal Medicine”, included 47 trials (Randomized Controlled Trials) with 3515 participants, looked at adults with any medical condition.

Mindfulness-based therapy: A comprehensive meta-analysis

• Large effect on anxiety.
• Moderate effect on depression.
• These effects held quite strongly at follow-up (follow up duration varied significantly between studies).
• In studies which compared meditation to cognitive behavioural therapy (CBT) there was little to no difference in effect.

Fine Print:  Published in “Clinical Psychology Review”.  Reviewed 209 studies with 12,145 participants.

Is meditation associated with altered brain structure? A systematic review and meta-analysis of morphometric neuroimaging in meditation practitioners

• Found 8 brain regions consistently altered in meditators with small effect size.
• These included areas associated with meta-awareness, body awareness, memory consolidation, self and emotional regulation & inter/intra hemispheric communication.
• There is some evidence that even very few hours of practice are required to show some initial changes in the brain.
• Concluded that “any firm claims about whether meditation truly causes differences in brain structure are still premature.”

Fine Print: Published in “Neuroscience and Biobehavioral Reviews”. Reviewed 21 studies with 300 meditation practitioners.

Effect of kindness-based meditation on health and well-being: A systematic review and meta-analysis.

• Moderately effective at reducing depression.
• Moderately effective at increasing mindfulness, compassion, self-compassion.
• Moderately effective at increasing positive emotion.

Fine Print:  Published in “Journal of Consulting and Clinical Psychology”. Reviewed 22 studies.

Sitting-Meditation Interventions Among Youth: A Review of Treatment Efficacy

• Meditation amongst both youth and adults has overall small-medium effect size on a wide variety of health related outcomes.
• Psychological / Behavioural outcomes show moderate-large effect, while physiologic outcomes showed small-moderate effect.

Fine Print:  Published in “Paediatrics”, Reviewed studies involving youth 18 years and younger.

Mindfulness meditation for younger breast cancer survivors: A randomized controlled trial

• Significant reduction in perceived stress.
• Did not show statistically significant effect on depressive symptoms.
• Significant reductions in pro-inflammatory gene expression & inflammatory signaling (WOW!)
• Statistically significant reduction of fatigue, sleep disturbance, and vasomotor symptoms and increased peace and meaning and positive affect.
• Intervention effects on psychological and behavioral measures were NOT maintained at three-month follow-up.

Fine Print: Published in “Cancer”. Randomized Controlled Trial involving 71 women who were diagnosed with breast cancer at or before the age of 50.

Mindfulness meditation for the treatment of chronic low back pain in older adults: A randomized controlled pilot study

• Statistically significant improvement in “Pain Acceptance” and physical function.

Fine Print: Published in “Pain”. 37 adults aged over 65 with chronic lower back pain.

A randomized controlled trial of mindfulness meditation versus relaxation training: Effects on distress, positive states of mind, rumination, and distraction

• Both meditation and relaxation groups experienced significant decreases in distress as well as increases in positive mood states over time, compared with the control group.
• Meditation showed a larger effect size on positive states of mind than relaxation.
• The meditation group also demonstrated significant decreases in both distractive and ruminative thoughts/behaviors compared with the control group (stronger for ruminative thoughts).

Fine Print: Published in “Annals of Behavioral Medicine”. Involved 83 students (mostly female) who reported psychological distress.

Effects of mindfulness meditation on chronic pain: a randomized controlled trial.

• Moderate effect on “vitality scale”.
• Medium to large size effect on anxiety and depression, better psychological well being and acceptance of pain.
• Non-significant effect on pain measures.

Fine Print: Published in “Pain Medicine”.  109 patients with nonspecific chronic pain.

Summary

The research to date shows that meditation seems to be effective at treating depression, stress and anxiety. It can also have an effect on better coping and functioning with pain as well as some evidence for improving cognitive functioning.

While its important to have a look at the scientific evidence, in the end you need to run an experiment on yourself to see if you feel better as a result of meditating, or not.  I found in my life it is extremely helpful and I definitely recommend that you give it a go.

Do you have any other thoughts or experiences about meditation and the evidence for it?

Let me know what you think in the comments below!

 

Further Reading:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4471252/ – this article is quite interesting especially in explaining the different type of meditation practices.

http://marc.ucla.edu/ – mindfulness / meditation program used in one of the studies above.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4630307/ – study on Loving Kindness Meditation.

http://www.ncbi.nlm.nih.gov/pubmed/23541163 – RCT study on effect of meditation on Generalized Anxiety Disorder.

http://www.ncbi.nlm.nih.gov/pubmed/17266067 – “Mindfulness meditation alleviates depressive symptoms in women with fibromyalgia”.