Mindfulness-based interventions for the treatment of physiological pathology

Abstract

Mindfulness-based interventions (MBIs) are structured programs that employ mindfulness to alleviate symptoms of psychiatric, psychosomatic or physical conditions. While the benefit of MBIs for psychopathology is well established, research on MBIs for physiological conditions is still in it's infancy and possible mechanisms of actions are rarely discussed. However, integrating cost-effective MBIs into medical interventions might offer novel multidisciplinary treatment options for conditions with underlying psychophysical or chronic inflammatory states. Accordingly, possible mechanisms of action of MBIs that exert influence on physiological diseases are evaluated. Namely, the mindfulness stress buffering hypothesis, the mind-body genomics model and a reduction in negative affect reduction theory are discussed. The examination indicates that MBIs might work by reducing chronic inflammory states, altering gene expression and affecting hormonal secretion. Further, the reduction of negative affect seems to be associated to various positive health outcomes. Preliminary research findings reveal moderate effect sizes in the treatment of conditions such as cardiovascular disease, psoriasis, diabetes and chronic pain. However, the results should be treated with caution as control-groups and follow ups were often absent. Further, a clear definition of mindfulness is necessary for improved scientific operalization. Problematic is that only one MBI incorperates physical exercise which might confound positive health outcomes. Nevertheless, the reviewed literature indicates preliminary support for the hypothesis, that MBIs may be suitable for complementary treatment of physical conditions.

Assessing the potential of Mindfulness Based Interventions for the treatment of physiological pathology

The concept of mindfulness gained widespread popularity in today's society as a tool for self-improvement, performance enhancement as well as for benefitting overall health. Simultaneously mindfulness courses have become accessible to the wide public through smartphone applications as shown by the fact that the European commercial app stores alone offer at least 192 mindfulness-focused applications (Schultchen et al., 2020). Also, mindfulness has been incorporated into the agenda of companies to improve employee's satisfaction, efficiency or to protect them against burnouts (Lomas et al., 2017). However, not only the mainstream use mindfulness but also the scientific investigation of the effects of this ancient practice is flourishing in the last decades.

Mindfulness is an umbrella term for a variety of forms of meditation or “mental exercise” that have their origin in various religious or spiritual philosophies and imply a wide range of similar but still distinct practices (Lutz et al., 2007). The discovery that mindfulness practices possess clinical potential for a variety of mental health conditions (Baer, 2003) led to their integration into established psychotherapeutic interventions such as cognitive behavioural therapy (CBT). Thus, mindfulness-based cognitive therapy (MBCT), mindfulness-based stress reduction (MBSR) and acceptance and commitment therapy (ACT) are the most prominent and established forms of current mindfulness-based interventions (MBIs) .

These MBIs adapted the ancient regularly spiritually connotated practice of meditation into a secular medical environment in the form of structured training programs (Carlson, 2012). All of these MBIs incorporate meditation techniques like sitting or loving-kindness meditation, while some further adapt yoga practices, for example hatha yoga sessions offered in MBSR (Baer, 2003). Figure 1 (Appendix) displays a detailed overview of the similarities and differences between the MBIs mentioned above.

The general approach to the concept of mindfulness of these MBIs can be summarized by the simple phrase of the founder of mindfulness-based stress reduction, Jon Kabat-Zinn: Mindfulness is “paying attention in a particular way: on purpose, in the present moment, and non-judgmentally” (Kabat-Zinn, 1994, p.4). Inducing a state of consciousness which is distinctive from normal wakeful alertness, is the aim of the meditation praxis. Subsequently, this state is accompanied by measurable cognitive and physiological changes and has the overall purpose of altering desired and reducing undesired traits. (Lutz et al., 2007). The form of concentrative meditation where attention is exclusively focused on the breath is often described as the first stage in mastering the skill of mindfulness. More advanced practitioners engage in “open awareness” where attention is receptive to the whole field of an experience without the constraint to an explicit focus point (Jha et al., 2007). Moreover, practicing mindfulness can be considered as a form of attentional training (Teper et al., 2013) with beneficial effects for overall cognitive functioning in healthy individuals as well as in clinical populations. This clinical potential of MBIs has been validated repeatedly in the last decades.

The most prominent findings of mindfulness-based interventions for psychopathology include significant improvement in patients with anxiety disorders (J. Kabat-Zinn et al., 1992), alleviation of depression symptoms (Kenny & Williams, 2007) and also depression relapse prevention (Shallcross et al., 2018). Further conditions that were demonstrated to improve through mindfulness are post-traumatic stress disorder (Boyd et al., 2018) and attention deficit hyperactivity disorder (Mitchell et al., 2015). Preliminary findings also suggest its application for the treatment of obsessive compulsory disorder (Hanstede et al., 2008), eating disorders (Kristeller & Hallett, 1999) and even some improvement in mental state and psychosocial functioning in schizophrenia patients has been noted (Wang et al., 2016). Despite all the promising findings, the underlying mechanisms that account for MBIs effectiveness are only vaguely understood to date as most studies merely focus on clinical improvements.

However, the finding that MBIs improve meta cognition (Zeidan et al., 2010) seems to explain their effects in various psychopathologies. Meta cognition can be described as the awareness and reflection of ongoing thought processes and mental states (Zeidan et al., 2010). This ability is often diminished in psychopathology - a major feature of depression for example is rumination, where an individual gets stuck in self-referential emotional processing and is unable to disengage from those distractors (Koster et al., 2011). Mindfulness practices in turn encourage the individual to carefully observe their thought patterns and to disengage from thoughts by directing the attention back to the breath. Further, the components of non-judgemental acceptance and present-moment awareness that are cultivated by mindfulness practices, seem to contribute to increased executive control (Teper et al., 2013). This improved meta-cognition and executive control have the potential to enhance the overall self-regulation of attention (Tang et al., 2007). A consequence of improved attention regulation is enhanced emotion-regulation, which is crucial in psychopathologies where negative affect is often characteristic (Teper et al., 2013).

The alteration of executive control has also received support by brain imaging studies. Accordingly, functional and structural changes in the anterior cingulate gyrus (ACC) and the dorsolateral prefrontal cortex (PFC), both structures involved in attention regulation and cognitive control, have been found in fMRI studies (Tang et al., 2015). Simplified - mindfulness enhanced emotion regulation seems to work by strengthening prefrontal cognitive control mechanisms and a simultaneous downregulation of activity in affect processing regions such as the amygdala (Tang et al., 2015).

However, research on MBIs often relies on self-reports as outcome measures of improvement and therefore an important contribution and advance was made by the discovery that decreased cortisol levels serve as a biological marker of MBIs effectiveness in psychological and physiological stress reduction (Matousek et al., 2010). Cortisol is the body's major stress hormone, that is secreted by the adrenal glands in response to acute or chronic stress. Its release is mediated by the hypothalamic-pituitary adrenal (HPA) axis, the central stress response system of the body (Watson & Mackin, 2006). Hyperactivity of the HPA axis and chronically elevated levels of cortisol have been previously linked to a variety of mood disorders and respectively, successful treatment was shown to lead to a normalization of functioning (Watson & Mackin, 2006).

Importantly, not only psychological conditions, but also a wide range of physiological disorders have identified chronic elevated stress and cortisol levels as a major risk factor.

Autoimmune, infectious, cardiovascular diseases and even some virally mediated forms of cancers have been previously linked to psychological stress (Cohen et al., 2007). The accumulating evidence that reports decreased cortisol levels after a participation in MBSR programs (Matousek et al., 2010) implicates that individuals with physiological disorders might also benefit from mindfulness based interventions.

Accordingly, recent developments in the treatment of physical conditions aim for multidisciplinary treatment approaches for conditions that include a psychophysical component. Chronic pain treatments offer a good example in which primarily symptom reduction was the main aim from a medical perspective (Johnston et al., 2010). Consecutive, developments in the area of pain management, however, led to biopsychosocial models of pain and illness that challenge traditional dualistic viewpoints which separate the functioning of body and mind (Gatchel et al., 2007). The biopsychosocial model explains illness as a complex interaction between biological, psychological and social factors and assumes that psychosocial factors such as emotional stress could influence the course and treatment of medical disorders (Gatchel et al., 2007).

As outlined in the beginning, MBIs can improve psychological conditions through enhanced emotion regulation. Considering the perspective of a biopsychosocial model of medical conditions, chronic medical conditions could also benefit from such an effect of MBIs. Additionally, MBIs might offer a possibility to address secondary psychological problems that frequently arise due to chronic physical conditions such as anxiety, depression or concentration difficulties (Crowe et al., 2016).

While the benefit of MBIs for psychopathology is already substantially established and acknowledged, the literature on MBIs for physiological conditions is still limited and possible mechanisms of actions are rarely discussed. Nevertheless, MBIs could provide a relatively cost-effective program to a wide range of of chronic illnesses as complementary means to medical interventions. A shift in the understanding of health and disease that takes into account the body-mind interplay could be of great interest if one considers phenomena like overprescription. Overprescription has been a major contributor to the U.S. opioid crisis, a partly self-inflicted public health crisis (Makary et al., 2017). Particularly in the U.S. physicians tend to prematurely prescribe pain killers or opioids for conditions such as chronic pain due to a limited number of alternative treatments (Volkow et al., 2017). Phenomena like this demonstrate the need of fostering a better understanding of the psychophysiological aspects of disease. Applying this knowledge into advanced multidisciplinary treatment options in turn could contribute to the prevention of incidents such as overprescription.

The question at hand is therefore: How could mindfulness-based-interventions contribute to the treatment of physiological conditions? The purpose of this review is to outline the status quo of research on MBIs in the treatment of physiological conditions and to highlight possible mechanisms of action. The aim is further explore possible application fields for the future.

Current status of research on MBIs for medical conditions

Research on mindfulness-based interventions for long-term medical conditions is a rather recent development, with the majority of clinical trials published in the last 5 years (Crowe et al., 2016). However, preliminary research results suggest health benefits across a wide spectrum of physical conditions. A meta-analysis by Grossman et al. (2004) critically examined studies with incorporated control groups that indicated positive effects of MBIs in the treatment of various chronical illness. Coronary artery diseases, mixed cancer diagnoses, chronic pain, obesity and fibromyalgia were the main inspected physical conditions. The results of the meta-analysis showed consistent and relatively robust levels of effect sizes among diverse samples in the assessed parameters of physical well-being, including sensory pain, physical impairment and medical symptoms. Moreover, a review by Crowe et al. (2016) further indicates significant improvements in irritable bowel syndrome, sleep disorders and moderate improvements in asthma, tinnitus and chronic pain conditions after a MBSR intervention.

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