How it (Mindfulness) Works? (Part 1)

Following on from our previous blog Neural mechanisms of mindfulness meditation we now use abbreviated excerpts form a very good researcher Eric Garland into how possible mindfulness helps repair, via meditation based neuroplasticity, those areas and networks of the brain which are impaired or do not function adaptively  in the addicted brain.

In this review paper, they described how mindfulness-based interventions (MBIs) may target neurocognitive mechanisms of addiction at the attention-appraisal-emotion interface.

“Mindfulness Training Ameliorates Addiction by Targeting Neurocognitive Mechanisms

Empirical evidence is presented suggesting that MBIs ameliorate addiction by enhancing cognitive regulation of a number of key processes, including: clarifying cognitive appraisal and modulating negative emotions to reduce perseverative cognition and emotional arousal; enhancing metacognitive awareness to regulate drug-use action schema and decrease addiction attentional bias; promoting extinction learning to uncouple drug-use triggers from conditioned appetitive responses; reducing cue-reactivity and increasing cognitive control over craving; attenuating physiological stress reactivity through parasympathetic activation; and increasing “savoring” to restore natural reward processing.

Although mindfulness is an English term linked with a set of contemplative practices and principles originating in Asia over 2500 years ago…

MBIs are centered on practices designed to evoke the state of mindfulness, a mindset characterized by an attentive and non-judgmental metacognitive monitoring of moment-by-moment cognition, emotion, perception, and sensation without fixation on thoughts of past and future (60, 61)…During focused attention, attention is sustained on an object while the practitioner alternately acknowledges and lets go of distracting thoughts and emotions. Objects of focused attention practice can include the sensation of breathing; the sensation of walking; interoceptive  feedback about the body’s internal state etc…

Focused attention practices are often the precursor to open monitoring forms of mindfulness meditation. During open monitoring, a state of metacognitive awareness is cultivated wherein mental contents are allowed to arise unperturbed without suppression or distraction while the quality of awareness itself remains the primary focus of attention (61)

Putatively, focused attention and open monitoring emphasize or differentially activate different cognitive capacities during the mindful state, including attentional vigilance, attentional re-orienting, executive monitoring of working memory, response inhibition, and emotion regulation (62).

Engaging in these practices repeatedly over time may induce neural and cognitive plasticity (7); recurrent activation of the mindful state during meditation may leave lasting neurobiological traces that accrue into durable changes in the dispositional propensity to be mindful in everyday life even while not meditating (64).

Germane to the current discussion of neurocognition in addiction, dispositional mindfulness is significantly inversely associated with addiction attentional bias (1) and craving (66), positively associated with autonomic recovery from stress and substance cue-exposure (67), and correlated with various indices of cognitive control (6870). MBI-related increases in dispositional mindfulness might be mediated through neuroplasticity stimulated by experience-dependent alterations in gene expression (71, 72).

Indeed, cross-sectional studies have demonstrated significant differences in gray matter volume between meditation practitioners and meditation-naïve controls, particularly in regions of PFC that instantiate cognitive control (e.g., inferior frontal gyri) and higher-order associative processing (e.g., hippocampus) (7377). Moreover, longitudinal research has shown that participants in an 8-week MBI evidenced increased gray matter density in posterior cingulate cortex, temporo-parietal junction, and cerebellum, compared to controls (78), and reduced amygdala volume that correlated with the degree of stress-reduction achieved from mindfulness training (79).

Through focused attention and open monitoring forms of meditation, MBIs exercise a number of neurocognitive processes believed to go awry in addiction. Indeed, MBIs may be fruitfully conceptualized as means of training or exercising prefrontally mediated cognitive control networks which have become atrophied or usurped in the service of drug seeking and use. By strengthening PFC functions and the ability of the PFC to modulate other brain networks in a context-dependent manner, MBIs may provide the global benefit of enhancing neurocognitive flexibility…(e.g., cognitive regulation of automaticity, attention, appraisal, emotion, urges, stress reactivity, reward processing, and extinction learning).

These processes do not operate in isolation; they are linked in mutually interdependent, interpenetrating, recursive networks [for reviews, see Ref. (2, 3)]. MBIs may restructure dysregulated processes by strengthening functional connectivity and efficiency of prefrontally mediated self-regulatory circuits (see Figure2). Below, we propose a number of hypothetical neurocognitive targets that could mediate the therapeutic effect of MBIs on addictive behavior.

FIGURE 2

 

Figure 2. Mindfulness-centered regulation: the central tenet of this model posits that mindfulness-based interventions (MBI’s) may remediate dysregulated habit behaviors, craving, and affect primarily by way of strengthening functional connectivity: (1) within a metacognitive attentional control network (PFC, ACC, Parietal); and (2) between that metacognitive attentional control network and the (a) habit circuit, (b) craving circuit, and (c) affect circuit.

HABIT RESPONSES

Substance dependent individuals typically experience euphoria during initial stages of drug-use. Yet, as experience with the drug increases, the reward associated with drug-taking becomes dramatically attenuated. Despite diminishing returns in positive emotional experiences resulting from substance use, dependent users continue to use their drug of addiction. Undergirded by neuroplastic changes in striatal circuitry, habitual drug-use becomes an overlearned process that can become automatized (12, 80).

Though more investigation is needed to elucidate effects of mindfulness on brain-behavior relations subserving drug-use action schemas, early research on the effects of mindfulness on behavioral measures of automaticity has emerged [e.g., Ref. (82)]. Such research provides a theoretical foundation for the potential efficacy of MBIs for interrupting drug-use action schemas. Hypothetically, mindfulness training may increase awareness of the activation of drug-use action schemas when triggered by substance-related cues or negative emotion, thereby allowing for the disruption of automatized appetitive processes with a controlled coping response.

As posited in our model of mindfulness-centered regulation (Figure 2), mindfulness training may enhance functional connectivity in a cortico-thalamic loop including prefrontal, cingulate, parietal, and dorsal thalamus nodes, strengthening an executive regulatory circuit providing feedback to the striatum and medial temporal lobe. This feedback process is theorized to allow for greater consciousness of thoughts and behaviors that were previously enacted with little conscious awareness.

The practice of mindfulness in daily life is focused on developing awareness of automatic behavior. Indeed, many MBIs prescribe informal mindfulness practices where individuals are instructed to engage in everyday, repetitive tasks (e.g., washing the dishes) with full consciousness of the sensorimotor aspects of the activity. Such informal mindfulness practices are designed to reduce mind-wandering and strengthen conscious control over automaticity.

Potentially as a result of such practices, mindfulness training has been shown to decrease habit behavior (83) and reduce rigid adherence to scripted cognitive responses (82). These findings accord with early theoretical accounts which conceptualized mindfulness meditation as a form of “deautomatization,” whereby patterns of motor and perceptual responses which had been rendered automatic and unconscious through repetition are reinvested with conscious attention (84).

Thus, is plausible that mindfulness training may deautomatize habitual addictive responses through both formal meditations focused on regulating automatic appetitive impulses as well as informal mindfulness practices designed to increase generalized awareness of automaticity. In light of findings suggesting that conscious cognitive control disrupts automatic processing (20, 8587), mindfulness training may interrupt drug-use action schemas by augmenting top-down control via a frontoparietal metacognitive attention network, facilitating the strategic deployment of self-regulatory processes to reduce or prevent substance use. The effects of mindfulness training on inhibition of habit responses might be indexed with performance on an Emotional GoNoGo task (88), where subjects would be asked to withhold automatized “go” responses in the context of emotional interference from a drug-related (i.e., a drug-related background image) or negative affective stimulus (i.e., an aversive background image).

To be Continued…

References

1. Garland, E. L., Froeliger, B., & Howard, M. O. (2013). Mindfulness  training targets neurocognitive mechanisms of addiction at the attention-appraisal-emotion interface. Frontiers in psychiatry, 4.

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