Table 2.
Studies included in the narrative review and a summary of their findings on psychological processes, autonomic and neurobiological processes assessed.
| Outcome assessed | Author | Findings | Study type |
|---|---|---|---|
| Mindfulness | [38] | Kindness-based meditation increased mindfulness (FA constructive family) | SR & MA |
| [39] | OM meditation increased mindfulness and mediated impacts of meditation on psychological outcomes | SR & MA | |
| Self-compassion | [40] | Various meditation forms increased mindfulness | SR |
| [38] | Kindness-based meditation (FA constructive family) increased self-compassion | SR & MA | |
| [41] | OM studies increased self-compassion | SR & MA | |
| [39] | OM meditation increased self-compassion and mediated effects on psychological outcomes | SR & MA | |
| Rumination | [39] | OM meditation decreased rumination and mediated impacts of meditation on psychological outcomes | SR & MA |
| [42] | OM/FA meditation-based study reduced rumination compared to treatment as usual and a waitlist control, but not compared to an active control group | SR & MA | |
| Attention | [43] | Various meditation forms enhanced executive control | SR |
| [44] | Pure mindfulness meditation more effective at impacting attention than comprehensive MBSR programs | SR & MA | |
| [45] | Programs that included FA and OM produced a significant effect on overall cognition | SR & MA | |
| [46] | FA and OM had a medium effect on attention | SR & MA | |
| Blood pressure | [47] | TM (oriented focused attention) lowered SBP and DBP | Review of SR & MAs |
| [88] | FA meditation decreased SBP, OM meditation did not. No change in DBP | SR & MA | |
| [48] | Both FA (TM) and a combination of non-transcendental meditation forms (varied) lowered ambulatory and non-ambulatory SBP and DBP | SR & MA | |
| Heart rate | [88] | OM meditation decreased HR, FA did not | SR & MA |
| HRV | [49] | Varied meditation forms analysed together did not influence HRV | SR & MA |
| [88] | OM and oriented FA meditation interventions did not influence HRV | SR & MA | |
| [50] | OM meditation interventions did not influence HRV | SR & MA | |
| Inflammatory proteins | [51] | OM reduced CRP and found a lack of replicated effects for IL-1, IL-6, IL-8, IL-10 | SR & MA |
| [88] | OM did not decrease CRP, IL-6. TNF-a decreased following combined analysis of various meditation forms | SR & MA | |
| [50] | OM did not decrease IL-6 or CRP | SR & MA | |
| [52] | OM did not influence IL-6, IL-8, TNF-α, IFN-γ, IL-10 | SR | |
| Cortisol | [53] | Varied meditation forms (mostly FA) analysed together reduced blood and salivary cortisol | SR & MA |
| [54] | OM meditation interventions reduced salivary cortisol levels in within-participants studies but not RCTs | SR | |
| [88] | Buddhist walking and Integrated Amrita Meditation decreased blood cortisol. FA meditation did not decrease blood cortisol | SR & MA | |
| [55] | Both OM and FA forms of meditation influence salivary cortisol levels | SR | |
| [56] | OM (predominately MBSR) decreased salivary cortisol | SR & MA | |
| Medial prefrontal cortex; Dorsal medial prefrontal cortex | [57] | Cortical thickening seen in BA10 of long-term meditators, irrespective of the meditation type. Various meditation forms associated with greater white matter fibre density and/or coherence in anterior/mid cingulate cortex and morphological difference in orbitofrontal cortex | SR & MA |
| [124] | FA and OM associated with activation in BA10. FA meditation associated with activation on BA9 | SR & MA | |
| [58] | MM meditations activate the prefrontal cortex and anterior cingulate cortex | SR | |
| [59] | Greater prefrontal/frontal activity associated with various meditation forms | SR | |
| Posterior cingulate cortex/retrosplenial cortex | [57] | Various meditation forms associated with structural declines in posterior cingulate cortex | SR & MA |
| [124] | FA meditation associated with deactivation in BA 30, loving-kindness/compassion meditation associated with activation in BA 23/31 | SR & MA | |
| Inferior parietal lobule | [124] | FA meditation associated with deactivation in BA 39, loving-kindness/compassion meditation associated with activation BA 2/40 | SR & MA |
| Hippocampal formation | [57] | Various meditation forms associated with structural changes in hippocampus | SR & MA |
| [58] | Vipassana meditation resulted in a thicker right hippocampus | SR | |
| The insular cortex | [57] | Various meditation forms associated with structural changes in insular cortex (e.g. cortical thickness, cortical gyrification, gray matter concentration) | SR & MA |
| [124] | FA, OM associated with activation in BA13. Mantra recitation (FA) associated with deactivation in BA13 | SR & MA | |
| [59] | Various meditation forms associated with increased insular activity | SR |
BA=Brodmanns area, CRP=C reactive protein, FA=Focused attention, DBP = Diastolic blood pressure, HR=Heart rate, HRV=Heart rate variability, IL-1 = Interleukin-1, IL-6 = Interleukin-6, IL-8 = Interleukin-8, IL-10 = = Interleukin-10, IFN-γ = interferon-gamma, IL-10 OM=Open monitoring, MA = Meta-analysis, MBSR = Mindfulness based stress reduction, MM = Mindfulness meditation, SBP=Systolic blood pressure, SR=Systemtic review, TM = Transcendental meditation, TNF-α = Tumour necrosis factor-alpha.