Neural effects on patients with major depressive disorder: systematic review

Vignaud, P., et al. (2018). Neural effects of mindfulness-based interventions on patients with major depressive disorder: A systematic review. Neuroscience & Biobehavioral Reviews, vol. 88, pp. 98-105, https://doi.org/10.1016/j.neubiorev.2018.03.004.

Abstract. Growing evidence has suggested that mindfulness-based interventions (MBIs) could have beneficial effects on the acute phase of depression and on the prevention of depressive relapse or recurrence. Despite growing clinical interest, the effects of MBIs on brain functioning in patients with MDD remain unclear. The aim of this systematic review was to assess the changes in brain functioning associated with MBIs in patients with MDD.

A systematic search was conducted, and of the 56 articles found, 8 were eligible. MBIs have modulatory effects on several brain regions implicated in the pathophysiology of MDD, such as the prefrontal cortex, the basal ganglia, the anterior and posterior cingulate cortices, and the parietal cortex. These regions have been implicated in self-awareness, attention and emotion regulation.

Some of these findings were consistent with the effects of MBIs observed in healthy subjects and patients with other psychiatric disorders, especially enhanced activity in the frontal and subcortical regions related to the improved somatosensory awareness. Further studies are needed to elucidate the mechanisms of MBIs in MDD.

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Interventions for psychiatric disorders

Goldberg, S. B., et al. (2018). Mindfulness-based interventions for psychiatric disorders: A systematic review and meta-analysis. Clinical psychology review, vol. 59, pp. 52-60, https://doi.org/10.1016/j.cpr.2017.10.011. Full text.

Highlights —

•  We examined the relative efficacy of mindfulness-based interventions on clinical symptoms of psychiatric disorders.

•  142 randomized clinical trials were included (N = 12,005 participants). Control conditions were coded on a five-tier system.

•  At post-treatment, mindfulness interventions were equivalent to evidence-based treatments and superior to other comparisons.

•  At follow-up, mindfulness interventions were equivalent to minimal and evidence-based treatments and superior to others.

•  The most consistent evidence for mindfulness-based interventions was seen for depression, pain, smoking, and addictions.

Beneficial for asthma?

Paudyal, P., et al. (2018). Meditation for asthma: Systematic review and meta-analysis. Journal of Asthma55(7), 771-778, https://doi.org/10.1080/02770903.2017.1365887. 

From the AbstractOur review suggests that there is some evidence that meditation is beneficial in improving quality of life in asthma patients. As two out of four studies in our review were of poor quality, further trials with better methodological quality are needed to support or refute this finding.

Adolescents with cronic diseases

Abujaradeh, H., et al. (2018). Mindfulness-Based Interventions among Adolescents with Chronic Diseases in Clinical Settings: A Systematic Review. Journal of Pediatric Health Care, https://doi.org/10.1016/j.pedhc.2018.04.001. Online ahead of publication.

Abstract. We aimed to determine the benefits/efficacy of mindfulness-based interventions (MBIs) implemented among adolescents with chronic diseases in clinical settings.

Nineteen eligible studies were included in this review. Fifteen studies included adolescents with psychiatric or pain disorders, and four included adolescents with a chronic physical disorders. Psychological outcomes and pain were examined in most studies with effect sizes for MBIs ranging from small to large.

MBI studies conducted in clinical settings mainly engaged adolescents with psychiatric or pain disorders. The effectiveness of MBIs on improving psychological outcomes were inconsistent. Large randomized trials are needed to examine the effectiveness of MBIs and should expand to include adolescents with chronic physical diseases.

Mindfulness-based treatment of addiction: the next wave of research

Garland, E. L., & Howard, M. O. (2018). Mindfulness-based treatment of addiction: current state of the field and envisioning the next wave of research. Addiction science & clinical practice, vol. 13, no1, pp. 14, https://doi.org/10.1186/s13722-018-0115-3. Full text.

Abstract. Contemporary advances in addiction neuroscience have paralleled increasing interest in the ancient mental training practice of mindfulness meditation as a potential therapy for addiction. In the past decade, mindfulness-based interventions (MBIs) have been studied as a treatment for an array addictive behaviors, including drinking, smoking, opioid misuse, and use of illicit substances like cocaine and heroin.

This article reviews current research evaluating MBIs as a treatment for addiction, with a focus on findings pertaining to clinical outcomes and biobehavioral mechanisms. Studies indicate that MBIs reduce substance misuse and craving by modulating cognitive, affective, and psychophysiological processes integral to self-regulation and reward processing.

This integrative review provides the basis for manifold recommendations regarding the next wave of research needed to firmly establish the efficacy of MBIs and elucidate the mechanistic pathways by which these therapies ameliorate addiction. Issues pertaining to MBI treatment optimization and sequencing, dissemination and implementation, dose–response relationships, and research rigor and reproducibility are discussed.

Meditation and prosocial behaviors (review & meta-analysis)

Kreplin, U., Farias, M., & Brazil, I. A. (2018). The limited prosocial* effects of meditation: A systematic review and meta-analysis. Scientific reports, vol. 8, no. 1, pp. 2403, DOI:10.1038/s41598-018-20299-z. Full text.

 Abstract. Many individuals believe that meditation has the capacity to not only alleviate mental-illness but to improve prosociality. This article systematically reviewed and meta-analysed the effects of meditation interventions on prosociality in randomized controlled trials of healthy adults.

Five types of social behaviours were identified: compassion, empathy, aggression, connectedness and prejudice. Although we found a moderate increase in prosociality following meditation, further analysis indicated that this effect was qualified by two factors: type of prosociality and methodological quality.

Meditation interventions had an effect on compassion and empathy, but not on aggression, connectedness or prejudice. We further found that compassion levels only increased under two conditions: when the teacher in the meditation intervention was a co-author in the published study; and when the study employed a passive (waiting list) control group but not an active one.

Contrary to popular beliefs that meditation will lead to prosocial changes, the results of this meta-analysis showed that the effects of meditation on prosociality were qualified by the type of prosociality and methodological quality of the study. We conclude by highlighting a number of biases and theoretical problems that need addressing to improve quality of research in this area.

* Prosocial behavior, or “voluntary behavior intended to benefit another”, is a social behavior that “benefit[s] other people or society as a whole”, “such as helping, sharing, donating, co-operating, and volunteering” (Wikipedia).

Is meditation associated with altered brain structure?

Fox, K. C., et al. (2014). Is meditation associated with altered brain structure? A systematic review and meta-analysis of morphometric neuroimaging in meditation practitioners. Neuroscience & Biobehavioral Reviews, no. 43, pp. 48-73, https://doi.org/10.1016/j.neubiorev.2014.03.016. Full text.

From the Abstract. Numerous studies have begun to address how the brain’s gray and white matter may be shaped by meditation. This research is yet to be integrated, however, and two fundamental questions remain: Is meditation associated with altered brain structure? If so, what is the magnitude of these differences?

To address these questions, we reviewed and meta-analyzed 123 brain morphology differences from 21 neuroimaging studies examining ∼300 meditation practitioners. Anatomical likelihood estimation meta-analysis found eight brain regions consistently altered in meditators, including areas key to meta-awareness (frontopolar cortex/BA 10), exteroceptive and interoceptive body awareness (sensory cortices and insula), memory consolidation and reconsolidation (hippocampus), self and emotion regulation (anterior and mid cingulate; orbitofrontal cortex), and intra- and interhemispheric communication (superior longitudinal fasciculus; corpus callosum). 

Publication bias and methodological limitations are strong concerns, however. Further research using rigorous methods is required to definitively link meditation practice to altered brain morphology.

For an update by the same authors, see “Alterations in the structure of the brain — review & implications.”