Meditation and yoga as mind-body interventions

: the psychobiological effects and individual differences

Abstract

There is considerable evidence for the effectiveness of mind-body interventions (MBIs) in improving mental and physical health in various clinical and non-clinical populations, but there are several gaps that remain poorly understood. The aim of this thesis was to expand the literature on MBIs by answering three major questions: Are changes in gene expression a mechanism of MBIs? Do MBIs work for prisoners with personality disorders? What participant baseline characteristics influence the response to meditation? To answer the first question related to gene expression as mechanisms of MBIs, we searched PubMed throughout September 2016 to look for studies that have used gene expression analysis in MBIs (i.e., mindfulness, yoga, Tai Chi, Qigong, relaxation response, and breath regulation). Due to the limited quantity of studies, we included both clinical and non-clinical samples with any type of research design. Eighteen relevant studies were retrieved and analysed. Overall, the studies indicate that these practices are associated with a downregulation of nuclear factor kappa B (NF-kB) pathway; this is the opposite of the effects of chronic stress on gene expression and suggests that MBI practices may lead to a reduced risk of inflammation-related diseases. However, it is unclear how the effects of MBIs compare to other healthy interventions such as exercise or nutrition due to the small number of available studies. More research is required to be able to understand the effects of MBIs at the molecular level. To answer the second question related to the effects of MBIs on prisoners with personality disorders, we recruited thirty prisoners with personality disorders who score high on psychopathy and have more than two personality disorders. They were assigned to a mindfulness intervention (n=10), to a yoga intervention (n=10), or to a wait-list control group (n=10) using stratified random sampling. Both mindfulness and yoga interventions were held at the same time and lasted three hours per day on five consecutive days. At baseline and after the intervention, we measured inflammation-related gene expression; resting state brain activity with electroencephalography (EEG); risk-taking and attention with cognitive tasks; event-related potentials (ERPs) related to the attention task; and stress, emotion regulation and mindfulness with questionnaires. Thirty participants were included in intention-to-treat analysis. We expected that both yoga and mindfulness will improve self-regulation (i.e., executive attention, emotion regulation and self-awareness), reduce stress and risk-taking behaviour, downregulate inflammatory-related gene expression and increase alpha and theta power. By using intent-to-treat analysis, we found no significant effects of interventions on any of these measures (p>.05). We found that mind-body interventions do not benefit prisoners with personality disorders and we assume that non-significant results are likely due to several methodological factors; a lockdown on the final day of the interventions, the length of the interventions and insufficient statistical power. The third question is related to individual differences in responding to meditation. While meditation classes, in particular mindfulness meditation classes, have become increasingly popular and more readily available, their outcomes vary. Some people reap benefits of the classes and become dedicated long-term practitioners, while others see no effect or might even experience adverse effects. If we would be able to distinguish positive responders from null and negative responders based on their individual characteristics, then those who would benefit the most could be targeted, while a different evidence-based technique could be applied to those for whom meditation would be contra-indicated. This personalised approach would not only save resources, but also help prevent harm. Surprisingly, there is no comprehensive study on this topic and only a limited number of studies have included data on how different people respond to meditation. In this chapter, we adopt a multilevel approach to evaluate extant evidence on the relationship between meditation and individual differences across four sources of variability: personality and other psychological variables, biological variables, illness severity in patients, and demographic factors. This thesis contributes to the current literature by providing evidence that gene expression changes are a mechanisms of health benefits associated with MBIs. Furthermore, it suggests that prisoners with personality disorders do not respond to short and intensive MBIs and it synthesises heterogeneous evidence from previous studies that examined baseline participant variables that influence the response to meditation.

Date of Award	Nov 2018
Original language	English
Awarding Institution	Coventry University Radboud University Nijmegen
Supervisor	Miguel Farias (Supervisor)