There’s little doubt about it – meditation is in vogue. In fairness, it probably always has been.

However, clinical and research interest in the effects of meditation programmes on psychological wellbeing has grown considerably in recent years. The development of mindfulness-based interventions has no doubt driven much of this interest. For example, running a PubMed keyword search for ‘mindfulness’ shows an approximate 30 fold increase in published research over the past 15 years.

Mindfulness-based interventions were first developed to treat stress and pain, particularly for people living with chronic illness (Kabat-Zinn, 1990). This programme became known as Mindfulness-Based Stress Reduction (MBSR) and evidence is increasing for a range of health benefits across a range of conditions (e.g. Grossman et al, 2004).

Likewise, NICE currently recommends the use of a similar programme, Mindfulness-Based Cognitive Therapy (MBCT), for the prevention of relapse in recurrent depressive disorders (NICE, 2009). The evidence base for MBCT is expanding for anxiety, psychosis, stress and a range of other mental health conditions. As a result, NHS services throughout the UK now offer MBSR or MBCT interventions to promote psychological wellbeing.

The vast majority of recent evidence has focused on mindfulness-based approaches, however, a new systematic review and meta-analysis conducted by researchers at Johns Hopkins University explores the potential health benefits of a range of meditation programmes (including mantra meditation techniques) alongside mindfulness-based interventions.

Often, research into meditation programmes is hindered by a lack of control conditions, small sample sizes and so forth. Similarly, as the authors suggest, placebo effects may be evident in meditation exercises, which needs to be considered when conducting research. For example, they argue that somebody with a positive attitude towards meditation at baseline may be likely to report greater benefits.

Methods

The authors searched MEDLINE, PsycINFO, EMBASE, PsycArticles, Scopus, CINAHL, AMED, the Cochrane Library and conducted hand searches for research into meditation programmes. The authors also reviewed the reference lists of included articles for any research missed by the initial search.

Studies were selected whose focus was on the effects of meditation on negative affect (eg. Anxiety and stress), positive affect (eg. Well-being), attention, the mental elements of health-related quality of life, pain, weight and health-related behaviours associated with stress (such as substance use, sleep, eating habits). They graded the strength of evidence based on risk of bias, directness, precision and consistency. Where possible, they conducted meta-analyses, using standardized mean differences to obtain aggregate effect sizes.

There were several inclusion criteria for the systematic review, including:

• Only RCTs with 1 or more control arm were included.
• Control group/s must receive the same level of attention, over a period of time comparable with the intervention group, so as to control for placebo effects (eg. wait lists) which the authors argue have often undermined the validity of previous studies.
• Only studies whose participants have a diagnosed clinical condition (defined as any mental health/psychiatric or physical health condition) were included. It is worth noting, however, that studies looking at stressed populations (without a clinical condition) were also included.

The literature search identified 17, 801 citations. After screening, 41 articles met the inclusion criteria and were included in the systematic review. No unpublished literature was included.

Results

The authors reported moderate evidence that mindfulness meditation programmes improved:

• Anxiety:
  • at 8 weeks (Effect size (ES) 0.38 [95% CI, 0.12 to 0.64])
  • and 3-6 months (ES 0.22 [95% CI, 0.02 to 0.43])
• Depression:
  • at 8 weeks (ES 0.30 [95% CI, 0.00 to 0.59])
  • and 3-6 months (ES 0.23 [95% CI, 0.05 to 0.42])
• Pain:
  • (ES 0.33 [95% CI, 0.03 to 0.62])

There was also low level evidence of improved stress/distress and mental health-related quality of life.

There was low level or insufficient evidence of any effects on positive mood, attention, sleep, weight or health-related behaviours.

In a comparative effectiveness analysis, there was no evidence that meditation programmes were better than any active treatment (ie drugs, exercise and other behavioural therapies).

Conclusions

The authors concluded that meditation programmes, particularly mindfulness-based meditation  programmes, can reduce psychological stress. There were moderate effect sizes for improvements to anxiety, depression and pain. However, it is worth highlighting that in these cases the 95% confidence intervals loom around the ‘no effect’ mark, which undermines the strength of the conclusions.

Nonetheless, the authors note:

Anxiety, depression and stress/distress are different components of negative affect. When we combined each component of negative affect, we saw a small and consistent signal that any domain of negative affect is improved in mindfulness programs when compared with a nonspecific active control.

This result is particularly interesting, as the authors continue that:

These small effect sizes are comparable with what would be expected from the use of an antidepressant in a primary care population but without the associated toxicities.

Mantra meditation programmes did not improve any of the reported outcomes, but as the authors point out, the strength of the evidence was poor.

Summary

The authors demonstrate that the current evidence on meditation programmes shows some promising effects of mindfulness-based interventions on affect (anxiety and depression), as well as pain. By adhering to strict inclusion criteria, the review reduces the risk of reporting inaccurate or nonspecific effects (such as expectations and preconceptions of meditation). However, even with strict criteria for inclusion, the strength of the evidence in many of the studies is poor, with large variability of effect sizes.

Limitations

• The included trials cover a wide range of interventions and there is considerable heterogeneity in terms of the dosing, frequency, duration and treatment techniques.
• The control groups used in the included studies are also very variable, which casts further doubt over the sense of pooling the results of these trials in a meta-analysis.
• The studies included in this review tend to have quite small sample sizes and short follow-up periods. As is almost always the case, bigger and longer trials are needed.
• The inclusion criteria did mean that many studies, particularly those exploring mantra meditation, were not included. In addition, the authors note that many meditation practices  (other than mantra and mindfulness-based programmes) exist, but due to a lack of randomised trials into their potential benefits, there is a lot more research needed before we can fully understand their impact on psychological wellbeing.
• The review does not report data on healthy subjects or anybody under 18.
• The review does not examine the mechanisms underlying psychological change in meditation exercises, and in doing so perhaps misses a trick. From a clinical psychology perspective, an important development for research into mindfulness (and other) meditation programmes is to understand how and why they facilitate cognitive and behavioural change.
• Put simply, what is the active ingredient in meditation programmes? If we can answer this, we can perhaps better design such programmes to treat specific mental health problems in the future.

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  Interested in mindfulness? Read the other Mental Elf blogs on the subject

  Links

Goyal M, Singh S, Sibinga EM et al. Meditation programs for psychological stress and well-being: A systematic review and meta-analysis. JAMA Intern Med. 2014 Jan 6. doi: 10.1001/jamainternmed.2013.13018. [Epub ahead of print] [PubMed abstract]

Goyal M, Singh S, Sibinga EMS et al. Meditation Programs for Psychological Stress and Well-Being (PDF). Comparative Effectiveness Review No. 124. Agency for Healthcare Research and Quality, Jan 2014. [Note: this review includes 6 fewer trials compared to the JAMA Intern Med reference given above].

Depression in adults (full guideline PDF). NICE, CG90, Oct 2009.

Grossman P, Niemann L, Schmidt, S, Walach, H. (2004). Mindfulness-based stress reduction and health benefits – A meta-analysis (PDF). Journal of Psychosomatic Research, Vol. 57(1), 35-43. doi: 10.1016/S0022-3999(03)00573-7

Kabat-Zinn, J. (1990). Full catastrophe living: Using the wisdom of your body and mind to face stress, pain and illness. Dell, New York.