It is well known the decaying of the gray matter with age. A growing body of research suggests that meditationpractices are associated with substantial psychological as well as physiological benefits. In searching for the biological mechanisms underlying the beneficial impact of meditation, studies have revealed practice-induced alterations of neurotransmitters, brain activity, and cognitive abilities (1). When correlating global and local gray matter with age, it is detected negative correlations within both controls and meditators, suggesting a decline over time. However, the slopes of the regression lines were steeper and the correlation coefficients were stronger in controls than in meditators. This particular quality of non-evaluative awareness can improve one’s physical and psychological health status, and therefore several approaches generally called “mindfulness-based interventions” (MBIs) have been developed and tested in the last 40 years (9), although only over the last three decades the mindfulness meditation practices have been increasingly incorporated into psychotherapeutic programs, to take advantage of these benefits . Evidence about their efficacy and effectiveness in improving mindfulness and health is rapidly accumulating.
The role of meditation
The anatomy of the hippocampus has been repeatedly reported to differ between meditators and non-meditators. The human hippocampus shows structural differences between meditators and non-meditators as well as between men and women. With the exact underlying neuronal mechanisms remaining to be established, studies linking meditation and brain structure are relatively sparse, but the hippocampus is consistently implicated as one of the structures altered in meditation practitioners (2). Surprisingly, there are scanty published studies that have addressed the question of whether meditation diminishes age-related brain degeneration (4). It has been suggested that this process is associated with a perceptual shift (12), in which one’s thoughts and feelings are recognized as events occurring in the broader field of awareness.
An underlying mechanism
Nothwithstanding, experiments using positron emission tomography or functional MRI (fMRI) within samples of novice or expert meditators indicated increased brain activation (compared to baseline) during meditation or mindfulness exercises in left and right hippocampal and parahippocampal regions (5) When deeming the neural basis of the complex mental task of meditation, there are a lot of involved changes in cognition, sensory perception, affect, hormones, and autonomic activity (6) Neuroimaging studies have begun to explore the neural mechanisms underlying mindfulness meditation practice with techniques such as EEG and functional MRI (12).
Group differences in the hippocampus and the right anterior insula, however, have each been identified in at least two of the studies. Furthermore, activation in both regions has been reported during meditative states, namely the hippocampus and the insula. The hippocampus is known to be critically involved in learning and memory processes, the modulation of emotional control, while the insula has been postulated to play a key role in the process of awareness, functions which have been shown to be important in the process and outcomes of mindfulness training (12). Cross-sectional studies have established that differences in regional gray matter are associated with performance abilities (13, 14), suggesting that an increase in gray matter corresponds to improved functioning in the relevant area.
What the evidence show
In the first study conducted by Eileen Luders et al, within a relatively large sample of meditators and well-matched controls, where global measures (hippocampal volumes) were complemented with refined local measures (radial hippocampal distances from surface to central core). After manually have labeled the hippocampus with a described procedure, the global left and right hippocampal volumes were established in mm3. Altogether, evaluated hyppocampal sizes were larger in meditators compared to controls, with up to 15% difference. ! These local effects were observed in several hippocampal regions in the left and right hemisphere though achieved significance primarily in the left hippocampal head (3). Larger hippocampal dimensions in long-term meditators may constitute part of the underlying neurological substrate for cognitive skills, mental capacities, and/or personal traits associated with the practice of meditation (2). In another exploratory single-group pilot longitudinal study it was examined the local gray matter changes over a six-week period of Mindfulness-based interventions (MBIs). The participants included six older adult community volunteers (M=66.5 years of age, SD=5.5, range=58-75; 66% female) with sleep disturbances. The Mindfulness-based interventions was delivered as a weekly, two-hour, six-session, group-based course in mindfulness meditation. Gray matter was measured voxel-wise pre- and post-intervention. It was found a significant gray matter increase identified within the precuneus, (posterior region of the medial parietal cortex, known to belong to the associative cortices, which is the widely distributed network sharing connections with other cortical and subcortical regions allowing the brain to integrate both external and self-generated information and to produce much of the mental activity that characterizes Homo sapiens sapiens) (10), possibly implicating meditation-induced changes of the default mode network. In contrast, observed significant gray matter decreases may have been driven by MBI-related remediation of brain architecture subserving sleep complaints (7).
Toward a mindfulness
The so called dispositional mindfulness (DM), is the tendency to be more mindful in daily life seems to be a sum of individual genetics and life experiences, and DM is not necessarily related to having participated in an mindfulness based intervention or practicing meditative exercises. DM can be measured by scales addressing mindfulness trait, e.g., the Mindful Attention Awareness Scale (MAAS) and the Five Facets Mindfulness Questionnaire (FFMQ) and it has been significantly related to several indicators of psychological and physical health including: higher levels of positive affect, improvement in personal stress management skills, and in adaptive emotional regulation (16). The mindfulness may encourage self-regulation, may enhance values clarification, as well as cognitive, emotional and behavioral flexibility and tolerance for facing difficult emotional states. Increasing the objectivity through which internal experience is viewed is intended to change one’s relationship to the thoughts, as opposed to changing the thoughts themselves. For instance, the tendency to be more mindful in daily life has been associated with better psychological functioning and reduced overall distress in cancer patients. Being aware of the present moment and refraining from judging inner experience were the 2 most important mindfulness skills for improvements of psychological functioning among cancer patients (17).
The mindfulness based intervention
The psychological construct of mindfulness refers to an awareness that emerges by intentionally paying attention to the present experience in a non-judgmental way, as was described by Kabat-Zinn (15). In other words, a “mindful” mind brings together attentional and attitudinal features at the same time, self-regulating the attention toward present-moment, direct experiences and attitude in a non-judgmental tone toward internal and external phenomena (physical, affective and behavioral). Interest in mindfulness has increased exponentially in recent decades in academic and clinical contexts. When approaching this mindfulness based intervention, a definition describes it as “paying attention in a particular way: on purpose, in the present moment, and non-judgmentally.” It has described mindfulness as a “way of being,” choosing to think of the work as a dynamic process, embedded within all of life, both intra- and inter-personal, rather than a static technique, practiced only “on the cushion” and thereby compartmentalized to “x” minutes per day (8) This particular quality of awareness has been associated to several indicators of physical and psychological health, and can be developed using mindfulness-based interventions (MBIs), and therefore MBIs have been successfully applied as preventive and complementary interventions and therapies in medicine and psychology. Together with quiet sitting and lying meditation practices, mindful physical exercises such as “mindful walking” and “mindful movement” are key elements in MBIs and couple muscular activity with an internally directed focus, improving interoceptive attention to bodily sensations. In addition, MBIs seem to share similar mechanisms with physical fitness (PF) by which they may influence cardiovascular responses to stress (9).
A growing body of literature has demonstrated that neural systems are modifiable networks and changes in the neural structure can occur in adults as a result of training. These findings not only imply a close link between meditation and brain structure, but also suggest possiblemodulating effects of meditation on age-related brain atrophy. Given that normal aging is associated with significant loss of brain tissue, meditation-induced growth and/or preservation might manifest as a seemingly reducing brain age in meditators (i.e., cerebral measures characteristic of younger brains). These results add to a growing literature depicts the impact of mindfulness and its relationship to improved psychological health. Moreover, specific mindfulness skills may be important in supporting these improvements, mainly taking into account the rising incidence and prevalence of brain atrophy conditions.