Spirituality and Aging

Helen Lavretsky

Disclosures

Aging Health. 2010;6(6):749-769. 

In This Article

Neurobiological Mechanisms of Spiritual Interventions

Research into neurobiological mechanisms of spiritual interventions is still limited by a small number of interventions and small sample sizes. Recent studies using clinical tools and functional neuroimaging have contributed to the growing knowledge of the biology of meditative practices. Most of the studies have been performed in younger adults or in mixed-age groups, and only noted age effect on the outcomes. However, the studies cited in the following paragraphs may guide the development of neurobiological research in older adults to address the effect on aging processes.

Physiological Studies of Meditation

Studies of the meditative state, comparing long-term to short-term meditators, report decreased sympathetic nervous activity, which is important for fight-or-flight reactions, and increased parasympathetic activity, which is important for relaxation and rest.[202–206] Several studies demonstrated predominant parasympathetic activity during meditation, associated with decreased heart rate and blood pressure, decreased respiratory rate and decreased oxygen metabolism.[203,207,208] However, a recent study of two separate meditative techniques suggested a mutual activation of parasympathetic and sympathetic systems by demonstrating an increase in heart rate variability during meditation.[209] Several studies of meditation have observed increases in blood plasma levels of melatonin[210–214] and serotonin,[210,215,216] and chronic increases in long-term meditators compared with controls, or acute increases directly after meditation. The physiological effects of meditation noted can be beneficial for the management of age-related illnesses, such as heart disease.

Neuroimaging Studies

Functional neuroimaging studies have been able to corroborate these subjective experiences by demonstrating the upregulation in brain regions of internalized attention and emotion processing with meditation. In a recent systematic review of neurobiological and clinical features of mindfulness meditation, Chiesa and Serretti reviewed the current evidence on the neurobiological changes and clinical benefits related to mindfulness meditation practice in psychiatric disorders, in physical illnesses and in healthy subjects.[217] From a clinical viewpoint, MBSR has shown efficacy for many psychiatric and physical conditions, and also for healthy subjects.[217]

Most modern functional imaging studies have been conducted in very small subject numbers, younger populations and without the use of control conditions.[218] Nevertheless, the findings seem to support the evidence that meditation leads to increased activation in frontal and subcortical brain regions, which are important for sustained attention and emotion regulation.[214] Hereby, the most consistent findings across meditation imaging studies are the functional upregulation of brain regions that are known to mediate attention control.[214] Meditation practices that focus on concentration of an object or mantra seem to elicit the activation of fronto–parietal networks of internalized attention;[219–224] while meditation techniques that focus on breathing may elicit additional activation of paralimbic regions of insula and anterior cingulated,[225] meditation techniques that focus on emotion may elicit fronto–limbic activation.[226] In the recent study of 8-week Kirtan Kriya meditation using single-proton emission tomography, Newberg and colleagues reported significant improvement in cognition in subjects with mild cognitive impairment and in normal older adults, as well as increases in cerebral blood flow in the prefrontal, superior frontal and superior parietal cortices.[222] Future studies will be needed to disentangle the brain activation patterns related to different meditation traditions.

Further evidence supports the hypothesis that meditation experiences are related to meditation-elicited changes in neurochemicals that are released by limbic brain regions and modulate mood. A functional imaging study using PET compared rest (listening to speech) to active meditation (meditation under verbal instruction) during Yoga Nidra meditation.[227] They found decreased binding of a radioactive tracer that competes with endogenous dopamine in the ventral striatum. This corresponds to an approximate 65% increase in dopamine release in limbic brain regions. All of the physiological effects reported in the neurobiological studies of spiritual intervention point to the potential benefit in improving the health of aging populations. Despite modest progress to date, future research should elucidate the intricate neurobiological mechanisms underlying meditative practices in aging populations.

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