Greater Anteroposterior Default Mode Network Functional Connectivity in Long-Term Elderly Yoga Practitioners

Long-term effects of yoga-based practices on neural, cognitive, psychological, and physiological outcomes in adults: a scoping review and evidence map

BACKGROUND

Compared with short-term practices, long-term yoga might promote differential qualitative and quantitative outcomes. Following JBI's and PRISMA-ScR guidelines, this scoping review followed an apriori and systematic protocol to document the long-term effects of yoga on neural, cognitive, psychological, and physiological outcomes, provide evidence maps for each yoga component, and summarize results identifying knowledge gaps and promising directions.

METHODS

Four databases (PubMed, Cochrane, LILACS, and PubPsych) were last searched in March 2023. Studies were included if they evaluated adults with > 1 year of practice, specified yoga-based practice(s) of interest, measured neural, cognitive, psychological, and/or physiological outcomes, were written in English, Spanish, or Portuguese, presented original data, and mentioned search terms in the title/abstract. Evidence maps for each yoga component followed a 4-level structure of outcome category, method, study design and literature size. Qualitative summaries followed the same structure, to facilitate information retrieval.

RESULTS

Out of 2270 screened studies, 65 were included (meditative studies = 36, predominantly postural studies = 25, breathing practice studies = 8). Physiologicaland neural outcomes were the most common, followed by psychological and cognitive outcomes. Although heterogeneous, neural results reveal structural and functional changes related to sensorimotor, interoceptive, emotion regulation, and executive functions. Physiologically, most studies have associated long-term practice with parasympathetic-driven autonomic, hormonal and immune responses, but some studies revealed sympathetic-driven or mixed responses, maybe due to the specific technique or individual differences. Psychological outcomes included lower levels of negative affect, psychopathological symptoms, and emotional reactivity. Cognitive measures have shown improved memory/cognition for older adults, but mixed or null effects for other constructs. Commonly, however, long-term practitioners demonstrated improved neural or physiological efficiency while performing cognitive tasks.

CONCLUSIONS

Future research should provide clear descriptions of the investigated yoga practice, employ more experimental paradigms, and refine statistical reports and models. We encourage researchers to work with specific overarching theoretical frameworks to refine research predictions, such as the neurovisceral integration model or predictive coding models; to consider motivational, cultural, and contextual factors that might influence long-term outcomes; and to develop systematic reviews and meta-analyses as next steps of evidence summary.

The efficacy of exercise interventions on depressive symptoms and cognitive function in adults with depression: An umbrella review

OBJECTIVE

This umbrella review aims to consolidate the evidence concerning the influence of exercise on depressive symptoms and cognitive performance in adults diagnosed with depression.

METHODS

An umbrella review of systematic reviews with meta-analyses investigating the effect of exercise on depression and cognition was performed. Databases (PubMed, Cochrane Library, Web of Science, Embase) were searched from inception until February 2024 for reviews of randomized controlled trials. Overlap within included reviews was assessed using the corrected covered area method (CCA). A random effects model was used to calculate overall pooled effect size with sub-analyses.

RESULTS

This study included 27 reviews, encompassing 190 experiments. In patients with depression, compared to the control group, exercise demonstrated a moderate effect size in reducing depressive symptoms (SMD = -0.67; SE = 0.04; p < 0.0001), with a Number Needed to Treat (NNT) of 2.78. When analyses were limited to data from studies with a low risk of bias, the effect on depressive symptoms was smaller (SMD = -0.38; SE = 0.07; p < 0.0001; NNT = 4.72). Exercise had a small effect on cognitive functions (SMD = 0.12; SE = 0.03; p < 0.0001), with an NNT for cognitive function treatment of 14.79.

CONCLUSIONS

All forms of exercise benefit patients with depression. However, for optimal intervention outcomes, it is essential to customize the intensity and type of exercise according to the specific characteristics of the patient's depressive symptoms and cognitive functions. It is recommended to implement a phased treatment approach for patients based on the intensity of exercise.

Remodeling the Epigenome Through Meditation: Effects on Brain, Body, and Well-being

Epigenetic mechanisms are key processes that constantly reshape genome activity carrying out physiological responses to environmental stimuli. Such mechanisms regulate gene activity without modifying the DNA sequence, providing real-time adaptation to changing environmental conditions. Both favorable and unfavorable lifestyles have been shown to influence body and brain by means of epigenetics, leaving marks on the genome that can either be rapidly reversed or persist in time and even be transmitted trans-generationally. Among virtuous habits, meditation seemingly represents a valuable way of activating inner resources to cope with adverse experiences. While unhealthy habits, stress, and traumatic early-life events may favor the onset of diseases linked to inflammation, neuroinflammation, and neuroendocrine dysregulation, the practice of mindfulness-based techniques was associated with the alleviation of many of the above symptoms, underlying the importance of lifestyles for health and well-being. Meditation influences brain and body systemwide, eliciting structural/morphological changes as well as modulating the levels of circulating factors and the expression of genes linked to the HPA axis and the immune and neuroimmune systems. The current chapter intends to give an overview of pioneering research showing how meditation can promote health through epigenetics, by reshaping the profiles of the three main epigenetic markers, namely DNA methylation, histone modifications, and non-coding RNAs.

Tai Chi Practice Buffers Aging Effects in Functional Brain Connectivity

Tai Chi (TC) practice has been shown to improve both cognitive and physical function in older adults. However, the neural mechanisms underlying the benefits of TC remain unclear. Our primary aims are to explore whether distinct age-related and TC-practice-related relationships can be identified with respect to either temporal or spatial (within/between-network connectivity) differences. This cross-sectional study examined recurrent neural network dynamics, employing an adaptive, data-driven thresholding approach to source-localized resting-state EEG data in order to identify meaningful connections across time-varying graphs, using both temporal and spatial features derived from a hidden Markov model (HMM). Mann-Whitney U tests assessed between-group differences in temporal and spatial features by age and TC practice using either healthy younger adult controls (YACs, n = 15), healthy older adult controls (OACs, n = 15), or Tai Chi older adult practitioners (TCOAs, n = 15). Our results showed that aging is associated with decreased within-network and between-network functional connectivity (FC) across most brain networks. Conversely, TC practice appears to mitigate these age-related declines, showing increased FC within and between networks in older adults who practice TC compared to non-practicing older adults. These findings suggest that TC practice may abate age-related declines in neural network efficiency and stability, highlighting its potential as a non-pharmacological intervention for promoting healthy brain aging. This study furthers the triple-network model, showing that a balancing and reorientation of attention might be engaged not only through higher-order and top-down mechanisms (i.e., FPN/DAN) but also via the coupling of bottom-up, sensory-motor (i.e., SMN/VIN) networks.

Altered regional neural activity and functional connectivity in patients with non-communicating hydrocephalus: a resting-state functional magnetic resonance imaging study

Introduction

Cognitive impairment is a frequent clinical symptom of non-communicating hydrocephalus (NCH) involving multiple domains, including executive function, working memory, visual-spatial function, language, and attention. Functional magnetic resonance imaging (fMRI) can be used to obtain information on functional activity in local brain areas and functional connectivity (FC) across multiple brain regions. However, studies on the associated cognitive impairment are limited; further, the pathophysiological mechanisms of NCH with cognitive impairment remain unclear. Here, we aimed to explore alterations in regional neural activity and FC, as well as the mechanisms of cognitive impairment, in patients with NCH.

Methods

Overall, 16 patients with NCH and 25 demographically matched healthy controls (HCs) were assessed using the Mini-Mental State Examination (MMSE) and fMRI. Changes in regional homogeneity (ReHo), degree centrality (DC), and region of interest-based FC were analyzed in both groups. The relationship between fMRI metrics (ReHo, DC, and FC) and MMSE scores in patients with NCH was also investigated.

Results and discussion

Compared with the HC group, the NCH group exhibited significantly lower ReHo values in the left precentral and postcentral gyri, and significantly higher ReHo values in the left medial prefrontal cortex (MPFC). The NCH group also showed significantly higher DC values in the bilateral MPFC compared with the HC group. Regarding seed-based FC, the MPFC showed reduced FC values in the right superior parietal and postcentral gyrus in the NCH group compared with those in the HC group. Moreover, within the NCH group, MMSE scores were significantly negatively correlated with the ReHo value in the left MPFC and the DC value in the bilateral MPFC, whereas MMSE scores were significantly positively correlated with FC values. To conclude, regional neural activity and FC are altered in patients with NCH and are correlated with cognitive impairment. These results advance our understanding of the pathophysiological mechanisms underlying the association between NCH and cognitive impairment.

Functional Connectivity Between Default Mode and Ventral Attention Networks Mediates the Effects of Chronotype on Daily Physical Activity

Daily physical activity (dPA) is closely related to circadian rhythm and chronotype. The functional connectivity (FC) within or between the default mode (DMN) and ventral attention network (vAN) were associated with dPA and chronotype. DMN-vAN FC was investigated for its role in chronotype and dPA. 153 participants completed the reduced version of the Morningness-Eveningness Questionnaire (rMEQ), dPA was measured via actigraphy (5-day), and then resting-state fMRI scans were performed. rMEQ scores and steps recorded by the actigraphic devices (with each hour as the time window to calculate steps for five consecutive days per hour, subsequently yielding the maximum number of steps and its corresponding time, ie, SM and SMT) represent chronotype and dPA respectively. The results found that the rMEQ scores were significantly negatively correlated with SMT. The positive correlation between the rMEQ scores and the DMN-vAN FC was significant. There were also significant positive correlations between SMT and DMN-vAN FC. Further analysis revealed that DMN-vAN mediates the relationship between chronotype and SMT. The FC of DMN-vAN may be the underlying neural mechanism through which chronotype influences dPA. These findings could support the development of reasonable activity schedules or specific intervention programs to improve physical health.

Reducing Stress with Yoga: A Systematic Review Based on Multimodal Biosignals

Stress is an enormous concern in our culture because it is the root cause of many health issues. Yoga asanas and mindfulness-based practices are becoming increasingly popular for stress management; nevertheless, the biological effect of these practices on stress reactivity is still a research domain. The purpose of this review is to emphasize various biosignals that reflect stress reduction through various yoga-based practices. A comprehensive synthesis of numerous prior investigations in the existing literature was conducted. These investigations undertook a thorough examination of numerous biosignals. Various features are extracted from these signals, which are further explored to reflect the effectiveness of yoga practice in stress reduction. The multifaceted character of stress and the extensive research undertaken in this field indicate that the proposed approach would rely on multiple modalities. The notable growth of the body of literature pertaining to prospective yoga processes is deserving of attention; nonetheless, there exists a scarcity of research undertaken on these mechanisms. Hence, it is recommended that future studies adopt more stringent yoga methods and ensure the incorporation of suitable participant cohorts.

The neurobiological effects of mind-body exercise: a systematic review and meta-analysis of neuroimaging studies

The neurobiological effects of mind-body exercise on brain activation, functional neural connections and structural changes in the brain remain elusive. This systematic review and coordinate-based meta-analysis investigated the changes in resting-state and task-based brain activation, as well as structural brain changes before and after mind-body exercise compared to waitlist or active controls based on published structural or functional magnetic resonance imaging randomized controlled trials or cross-sectional studies. Electronic database search and manual search in relevant publications yielded 34 empirical studies with low-to-moderate risk of bias (assessed by Cochrane risk-of-bias tool for randomized trials or Joanna Briggs Institute's critical appraisal checklist for analytical cross-sectional studies) that fulfilled the inclusion criteria, with 26 studies included in the narrative synthesis and 8 studies included in the meta-analysis. Coordinate-based meta-analysis showed that, while mind-body exercise enhanced the activation of the left anterior cingulate cortex within the default mode network (DMN), it induced more deactivation in the left supramarginal gyrus within the ventral attention network (uncorrected ps < 0.05). Meta-regression with duration of mind-body practice as a factor showed that, the activation of right inferior parietal gyrus within the DMN showed a positive association with increasing years of practice (voxel-corrected p < 0.005). Although mind-body exercise is shown to selectively modulate brain functional networks supporting attentional control and self-awareness, the overall certainty of evidence is limited by small number of studies. Further investigations are needed to understand the effects of both short-term and long-term mind-body exercise on structural changes in the brain.PROSPERO registration number: CRD42021248984.

Yoga Impacts Cognitive Health: Neurophysiological Changes and Stress Regulation Mechanisms

Yoga, a physical and contemplative practice, offers the practitioner a unique mind-body exercise experience demonstrating preliminary efficacy in improving cognitive health. We examine the evidence for underlying mechanisms that explain the yoga-cognition relationship in healthy older adults. The cognitive benefits of yoga may be the result of improved stress regulation and neurocognitive resource efficiency that facilitate bidirectional brain-body communication.

Promoting brain health through physical activity among adults exposed to early life adversity: Potential mechanisms and theoretical framework

Adverse childhood experiences such as abuse, neglect, and poverty, profoundly alter neurobehavioral development in a manner that negatively impacts health across the lifespan. Adults who have been exposed to such adversities exhibit premature and more severe age-related declines in brain health. Unfortunately, it remains unclear whether the negative effects of early life adversity (ELA) on brain health can be remediated through intervention in adulthood. Physical activity may represent a low-cost behavioral approach to address the long-term consequences of ELA on brain health. However, there has been limited research examining the impact of physical activity on brain health among adults with a history of ELA. Accordingly, the purpose of this review is to (1) review the influence of ELA on brain health in adulthood and (2) highlight evidence for the role of neurotrophic factors, hypothalamic-adrenal-pituitary axis regulation, inflammatory processes, and epigenetic modifications in mediating the effects of both ELA and physical activity on brain health outcomes in adulthood. We then propose a theoretical framework to guide future research in this area.

Yoga for Healthy Aging: Science or Hype?

Yoga, one of the world’s oldest health systems is receiving new attention for claims that it can contribute to healthy aging. Until recently, scientific evidence for its efficacy has relied heavily on small and poorly-designed research, but this is changing. Multiple, well-designed studies provide data showing that yoga practice has positive effects on cellular aging, mobility, balance, mental health, and prevention of cognitive decline—all areas of concern for older adults. Since the cost of implementing yoga-based community and home-based interventions is low—policymakers are also eyeing yoga practice as a cost-effective way to reduce medical costs and improve outcomes among a growing aging population. This commentary reviews the evidence for both physical and mental health benefits from yoga, as well as concerns about injuries that have been associated with certain types of yoga practice. It reveals a surprising range of yoga programs and difficulty levels that provide opportunities for almost anyone to participate and gain health benefits with practice.

Sleep, Cognition, and Yoga

Stress is one of the major problems globally, associated with poor sleep quality and cognitive dysfunction. Modern society is plagued by sleep disturbances, either due to professional demands or lifestyle or both the aspects, often leading to reduced alertness and compromised mental function, besides the well documented ill effects of disturbed sleep on physiological functions. This pertinent issue needs to be addressed. Yoga is an ancient Indian science, philosophy and way of life. Recently, yoga practice has become increasingly popular worldwide. Yoga practice is an adjunct effective for stress, sleep and associated disorders. There are limited well controlled published studies conducted in this area. We reviewed the available literature including the effect of modern lifestyle in children, adolescents, adults and geriatric population. The role of yoga and meditation in optimizing sleep architecture and cognitive functions leading to optimal brain functioning in normal and diseased state is discussed. We included articles published in English with no fixed time duration for literature search. Literature was searched mainly by using PubMed and Science Direct search engines and critically examined. Studies have revealed positive effects of yoga on sleep and cognitive skills among healthy adults as well as patients of some neurological diseases. Further, on evaluating the published studies, it is concluded that sleep and cognitive functions are optimized by yoga practice, which brings about changes in autonomic function, structural changes, changes in metabolism, neurochemistry and improved functional brain network connectivity in key regions of the brain.

Effects of Mind-Body Exercise on Brain Structure and Function: A Systematic Review on MRI Studies

Mind–body exercise has been proposed to confer both physical and mental health benefits. However, there is no clear consensus on the neural mechanisms underlying the improvements in health. Herein, we conducted a systematic review to reveal which brain region or network is regulated by mind–body exercise. PubMed, Web of Science, PsycINFO, SPORTDiscus, and China National Knowledge Infrastructure databases were systematically searched to identify cross-sectional and intervention studies using magnetic resonance imaging (MRI) to explore the effect of mind–body exercise on brain structure and function, from their inception to June 2020. The risk of bias for cross-sectional studies was assessed using the Joanna Briggs Institute (JBI) checklist, whereas that of interventional studies was analyzed using the Physiotherapy Evidence Database (PEDro) scale. A total of 15 studies met the inclusion criteria. Our analysis revealed that mind–body exercise modulated brain structure, brain neural activity, and functional connectivity, mainly in the prefrontal cortex, hippocampus/medial temporal lobe, lateral temporal lobe, insula, and the cingulate cortex, as well as the cognitive control and default mode networks, which might underlie the beneficial effects of such exercises on health. However, due to the heterogeneity of included studies, more randomized controlled trials with rigorous designs, similar measured outcomes, and whole-brain analyses are warranted.

Yoga and psychiatric disorders: a review of biomarker evidence

Traditionally, yoga has been used as a means for spiritual growth but over the past two decades or so its therapeutic benefits in psychiatric disorders have been scientifically explored. Yoga has been shown to be useful as a mono-therapy in mild to moderate depression and as an adjuvant in several psychiatric disorders including schizophrenia, anxiety disorders, substance use disorders and Mild Cognitive Impairment. Furthermore, systematic attempts have been made to understand the biological correlates of yoga in these psychiatric disorders. Given that no psychiatric disorder has strong and established biomarkers, it is interesting that preliminary research has demonstrated significant changes in certain important biomarkers following regular yoga practice. In this brief review, we provide an update on the effects of yoga on biochemical, neuro-physiological and neuro-imaging related bio-markers in psychiatric disorders. Although findings and trends are promising, much more research is warranted to establish a definite biological basis for yoga in psychiatry.

What Has Neuroimaging Taught Us on the Neurobiology of Yoga? A Review

Yoga is becoming increasingly popular worldwide, with several implicated physical and mental benefits. Here we provide a comprehensive and critical review of the research generated from the existing neuroimaging literature in studies of yoga practitioners. We reviewed 34 international peer-reviewed neuroimaging studies of yoga using magnetic resonance imaging (MRI), positron emission tomography (PET), or single-photon emission computed tomography (SPECT): 11 morphological and 26 functional studies, including three studies that were classified as both morphological and functional. Consistent findings include increased gray matter volume in the insula and hippocampus, increased activation of prefrontal cortical regions, and functional connectivity changes mainly within the default mode network. There is quite some variability in the neuroimaging findings that partially reflects different yoga styles and approaches, as well as sample size limitations. Direct comparator groups such as physical activity are scarcely used so far. Finally, hypotheses on the underlying neurobiology derived from the imaging findings are discussed in the light of the potential beneficial effects of yoga.

Yoga Effects on Brain Health: A Systematic Review of the Current Literature

Yoga is the most popular complementary health approach practiced by adults in the United States. It is an ancient mind and body practice with origins in Indian philosophy. Yoga combines physical postures, rhythmic breathing and meditative exercise to offer the practitioners a unique holistic mind-body experience. While the health benefits of physical exercise are well established, in recent years, the active attentional component of breathing and meditation practice has garnered interest among exercise neuroscientists. As the scientific evidence for the physical and mental health benefits of yoga continues to grow, this article aims to summarize the current knowledge of yoga practice and its documented positive effects for brain structure and function, as assessed with MRI, fMRI, and SPECT. We reviewed 11 studies examining the effects of yoga practice on the brain structures, function and cerebral blood flow. Collectively, the studies demonstrate a positive effect of yoga practice on the structure and/or function of the hippocampus, amygdala, prefrontal cortex, cingulate cortex and brain networks including the default mode network (DMN). The studies offer promising early evidence that behavioral interventions like yoga may hold promise to mitigate age-related and neurodegenerative declines as many of the regions identified are known to demonstrate significant age-related atrophy.

Sex and Age Dependencies of Aqueductal Cerebrospinal Fluid Dynamics Parameters in Healthy Subjects

Objectives

To assess the influence of age and sex on 10 cerebrospinal fluid (CSF) flow dynamics parameters measured with an MR phase contrast (PC) sequence within the cerebral aqueduct at the level of the intercollicular sulcus.

Materials and Methods

128 healthy subjects (66 female subjects with a mean age of 52.9 years and 62 male subjects with a mean age of 51.8 years) with a normal Evans index, normal medial temporal atrophy (MTA) score, and without known disorders of the CSF circulation were included in the study. A PC MR sequence on a 3T MR scanner was used. Ten different flow parameters were analyzed using postprocessing software. Ordinal and linear regression models were calculated.

Results

The parameters stroke volume (sex: p < 0.001, age: p = 0.003), forward flow volume (sex: p < 0.001, age: p = 0.002), backward flow volume (sex: p < 0.001, age: p = 0.018), absolute stroke volume (sex: p < 0.001, age: p = 0.005), mean flux (sex: p < 0.001, age: p = 0.001), peak velocity (sex: p = 0.009, age: p = 0.0016), and peak pressure gradient (sex: p = 0.029, age: p = 0.028) are significantly influenced by sex and age. The parameters regurgitant fraction, stroke distance, and mean velocity are not significantly influenced by sex and age.

Conclusion

CSF flow dynamics parameters measured in the cerebral aqueduct are partly age and sex dependent. For establishment of reliable reference values for clinical use in future studies, the impact of sex and age should be considered and incorporated.