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Stress is immunosuppressive. Research into this pernicious relationship between stress and disease has piqued interest in the ways that contemplative practices might positively influence the immune system. According to a large body of evidence, meditation appears to have profound effects on immune function in health and disease because of its ability to reduce stress.
Why does mindfulness reduce stress?
Two main facets of mindfulness meditation are equanimity and focused attention. Equanimity towards one’s thoughts decreases reactivity to stressful stimuli, and focused attention helps reduce the tendency towards the type of ruminative thinking that can activate the stress pathway. This relaxation response seems to have multiple effects on the body’s stress pathways. It enhances vagal tone, which in turn suppresses the activity of pro-inflammatory cytokines through the cholinergic anti-inflammatory pathway. It also reduces hypothalamic-pituitary-adrenal (HPA) activity in response to stressful situations, reducing basal levels of cortisol and meditating other downstream stress-related processes.
The majority of empirical evidence for meditation’s effect on the immune system support a protection and recovery model. Imagine being caught in a rainstorm without a raincoat and without a towel. In a torrent of stress, mindfulness is both the raincoat (preventative) and towel (palliative), so that, at the very least, stress is impeded in its course to reach downstream immune targets. Some lines of evidence are described below:
1) Richard Davidson has conducted studies on the relationship between affective style and brain lateralization, and has found that people with positive affect have increased right prefrontal activation compared to people with negative affect. In a recent study, Davidson and colleagues found that after an eight-week mindfulness program, subjects demonstrated both increased left-PFC activation as well as an increased antibody production after administration of a flu vaccine, indicating an enhanced immune response.
2) Amount of meditation practice in a 6-week compassion meditation program was positively correlated with a decrease in stress-induced interleukin-6 (a pro-inflammatory cytokine with immunosuppressive activity; increased IL-6 production is common among individuals with chronic stress and depression.)
3) Subjects who participated in a three-month mindfulness meditation program demonstrated increased activity in immune cell telomerase, an enzyme responsible for preventing immune cell death. Suppressed telomerase activity is related to increased stress perception. Increased telomerase activity is associated with decreased LDL cholesterol and epinephrine.
4) A “perception” approach to mindfulness and the immune system
Another proposed mechanism, in contrast to the stress-reduction paradigm, is a “perception” approach to meditation’s effect on the immune system, whereby one sensory modality shifts to accommodate another sensory modality. This perception approach is demonstrated by the classic “prism experiment”. If you are holding an object in your palm, you are receiving information from both visual and proprioceptive modalities. If a prism is placed in your line of vision, however, there is a perceptual discrepancy between the information from the two modalities. To overcome this discrepancy, one modality will attenuate to match the other. This “cross-modal adaptation” can also explain why mindfulness seems to positively influence the immune system. If one can visualize oneself as “healthy”, they can cause their immune system to attenuate to match the visualized information. However, there are two premises that must be accepted: a) the immune system is a sensory modality, and that b) visualization involves the same neurobiological processes that vision does and thus also functions as a sensory modality. This mechanism lacks substantial empirical support, however, and could benefit from further study. This mechanism may not pertain to mindfulness, which is more about an open, non-intrusive introspection. However, it may support visualization-related practices, such as Tibetan g Tum-mo yoga, in which practitioners are able to regulate their body temperature [LINK].
Benson, H., Beary, J.F., Carol, M.P. (1974). The relaxation response. Psychiatry, 37, 37-46.
Davidson, R.J., Kabat-Zinn, J., Schumacher, J., Rosenkranz, M., Muller, D., Santorelli, S.F., Urbanowski, F., Harrington, A., Bonus, K., Sheridan, J.F. (2003). Alterations in brain and immune function produced by mindfulness meditation. Psychosomatic Medicine, 65, 564-570.
Jacobs, T.L., Epel, E.S., Lin, J., Blackburn, E.H., Wolkowitz, O.M., Bridwell, D.A., Zanesco, A.P., Aichele, S.R., Sahdra, B.K., MacLean, K.A., King, B.G., Shaver, P.R., Rosenberg, E.L., Ferrer, E., Wallace, B.A., Saron, C.D. (2010) Intensive meditation training, immune cell telomerase activity, and psychological mediators. Psychoneuroendocrinology.
Olivo, E.L. (2009). Protection through the lifespan: the psychoneuroimmunological impact of Indo-Tibetan meditative and yoga practices. Annals Of The New York Academy Of Sciences, 1172, 163-71.
Pace, T.W.W., Negi, L. T., Adame, D.D., Cole, S.P., Sivilli, T.I., Brown, T.D., Issa, M.J., Raison, C.L. (2008). Effect of compassion meditation on neuroendocrine, innate immune and behavioral responses to psychosocial stress. Psychoneuroendocrinology.
Tausk F., Elenkov, I., Moynihan, J. (2008). Psychoneuroimmunology. Dermatologic Therapy. 21(1), 22-31.
Neuroimaging Research has grappled with the concept of a “resting brain”. Researchers interested in Consciousness have grappled with localizing subjective states of awareness and the elusive “self”. It seems that contemplative science is bringing both concepts to the table given the profound interest in tracing neurophenomenological states associated with “the self” and intentional, meditative practices.
All functional neuroimaging research has focused on Blood-oxygenation-level-dependent (BOLD) changes in the whole brain associated with a particular active, goal-directed, cognitive or emotional function and which has shown to be statistically different from BOLD activity across the whole brain during a “passive” baseline state. The baseline state that most researchers use is typically a 5-6 min long period of passive “rest”. The instructions are typically, “Let your mind freely wander” and “try not to think of anything in particular”. These instructions sound benign and appear to be the perfect baseline state, but as it turns out, [surprise…surprise] a wandering mind is quite active. The mind in this baseline state has shown to have a tendency to wander towards self-reflection (in the past and into the future). Some researchers have called this type of wandering, “mental time travel”.
Recently, a growing body of research has investigated the nature of this resting, or “default” state, and has found that brain activation previously considered to be spontaneous noise actually reflects the operation of active and functionally connected neural networks. These patterns of activation has been termed the default mode network (DMN), have been shown to increase during passive states of rest, to diminish during tasks involving attention or goal-directed behavior, and tend to implicate brain areas associated with self-reflection, internal mentation, and narrative self-focus. In many forms of psychopathology, the DMN has been found to be more active during resting states and less likely to decrease in activation during active goal-directed tasks, suggesting a relationship between psychopathology, excessive self-reflection or rumination [about past events], and increased self-projection [into the future].
In a recent study[Link] by friend and colleague, Judson Brewer at Yale University, adept meditators trained in meditation techniques rooted mostly in Theravada (vipassana/insight) traditions actively meditated using multiple types of meditation practices (Concentration, Loving-Kindness, Choiceless Awareness) while being imaged in the MRI. A “mind-wander” rest state was the baseline state in this case, and comparisons were made also between the adepts and a group of novices who had brief instructions how to perform each meditative practice.
As seen below, Experienced meditators demonstrate decreased DMN activation during meditation. Brain activation in meditators > controls is shown, collapsed across all meditations (relative to baseline). (A and B) BOLD activations were found to be greater in the left mPFC and PCC for adepts. Although, one should take note that the % change was very minimal (about .25 % at most). The mPFC and PCC are critical nodes of activation during typical mind wandering, self-reflection, and the core areas for the DMN.
Choiceless Awareness (green bars), Loving-Kindness (red), and Concentration (blue) meditations. Note that decreased activation in PCC in meditators is common across different meditation types. n = 12 per group.
What does this mean?
You may ask what this means and how it relates to mindfulness and mind-wandering. It suggests that adept meditators spend less time using the self-reflective network or “DMN” while meditating. This makes sense given the heavy reliance on concentration in these practices. But how about when adepts are simply “wandering” during passive rest? Are they like everyone else? Do they also reflect upon themselves in the past or into the future? This study did not quite capture the phenomenological differences between the groups, but it did find that the DMN had different functional connectivity patterns.
Using mPFC as a seed region for connectivity, they found increased connectivity with the fusiform gyrus, inferior temporal and parahippocampal gyri, and left posterior insula (among other regions) in meditators relative to controls during meditation. Using the PCC as a seed region, increased connectivity (compared with controls) was found with the dorsal ACC and DLPFC during all meditative states and baseline wandering, suggesting increased cognitive monitoring and working memory across both meditative and passive resting states. It would be helpful to know if there was a qualitative aspect of “wandering” that was about equal for meditators and controls.
Similarly, David Creswell and Lisa Kilpatrick demonstrated that 8-weeks of MBSR training showed increased functional connectivity of dmPFC (an anterior DMN region) with an auditory/salience neural network (especially with BA 22/39 (associated with auditory processing) and the dorsal ACC (involved in salience) . They suggest these results indicate greater positive coherence between self-referential, attention, and auditory sensory processing and may underlie greater attention and reflective awareness of auditory experience in MBSR trained subjects.
Again, the DMN is used here as a proxy for a “wandering mind”. Decreased activity in the cortical midline structures that make up this network reflects less self-reflection or narrative self-processing, and suggests more present-centered awareness, monitoring, and attention of interoceptive and exteroceptive stimuli in the environment and associated with the body. The reason I bring attention to this area of research is that contemplative neuroscientists will likely have to take these differences in the DMN between novices and adepts into consideration when scanning meditative states. In other words, a passive mind wandering state may be different between adepts and novices or naives. Thus, between groups comparisons should likely account for these differences and at the very least, quantify the qualitative aspects of mind wandering between groups.
ON THE OTHER HAND….
There is some evidence that mind wandering is adaptive. One study (for example) by Jonathan Schooler and colleagues demonstrates that increased mind wandering during a boring task increased creativity. Schooler has previously demonstrated a correlation between daydreaming and creativity—those who are more prone to mind-wandering tend to be better at generating new ideas.
See New Yorker write up [Link]
Here are some links to press related to these studies:
psychology today [Link]
- Meditation May Help Brains Rewire, Protect Against Mental Illness – KABC (kabc.com)
- Mind-wandering and mindfulness (psychologytoday.com)
- Our Wandering Minds…. (joannewellington.wordpress.com)
- MIND AND HEALTH Relax your mind and focus (tech.mit.edu)
- Meditation leads to less mind wandering, more doing (mentalflowers.wordpress.com)