A Systematic Review of the Neuropsychological and Systems-Biological Mechanisms of Yoga

Article Type: Narrative Review with a Systematic Approach

Erfan Shakibi
Holistic Yoga Teacher
Academic Member of the International Holistic Yoga Therapy Institute (IHYTI)
Member of the Psychology and Counseling Organization of Iran
M.A. in Psychology
www.ihyti.com

Abstract
Yoga, as a comprehensive mind–body intervention, has attracted considerable attention in neuroscience and clinical psychology in recent years. The aim of the present study was to systematically review the most recent evidence published between 2025 and 2026 regarding the acute and long-term effects of yoga on brain structure and function, executive functions, emotional regulation, attentional networks, and systemic changes, including gene expression and the gut–brain axis.Methods: A systematic search was conducted in major databases, including PubMed, Scopus, Web of Science, and Google Scholar, using combinations of the keywords “Yoga,” “Neuroplasticity,” “Prefrontal Cortex,” “Default Mode Network,” “Anxiety,” “Microbiome,” and “Alzheimer’s.” Of the 2,270 initially identified articles, 65 relevant studies, including randomized controlled trials, systematic reviews, scoping reviews, and cohort studies, were selected and analyzed based on the inclusion criteria. These criteria included implementation of a yoga intervention, assessment of neurological, psychological, or biological outcomes, publication in English or Persian, and publication in indexed journals.
Results: The synthesized evidence indicates that:
(1) At the acute level, even a single 30–60-minute yoga session significantly reduces anxiety and stress and is accompanied by activation of the right prefrontal cortex and reduced functional connectivity within the default mode network (DMN).
(2) At the long-term level, structural changes in somatosensory, interoceptive, and emotional-regulation regions have been observed, accompanied by improvements in memory among older adults.
(3) In the field of exercise psychology, yoga improves the orienting and conflict-control attentional networks, with relatively large effect sizes.
(4) At the systemic level, yoga is associated with modulation of gut microbiome composition, including increases in beneficial bacteria such as Faecalibacterium prausnitzii and decreases in pro-inflammatory bacteria in patients with Alzheimer’s disease, accompanied by marked improvements in cognitive scores and reductions in depressive symptoms. Preliminary evidence has also been reported regarding the positive effects of mudras (hand gestures) on information-processing speed.Based on the findings of this study, yoga, as an effective multilevel intervention, simultaneously influences neural, cognitive, and biological targets. Despite the promising evidence, larger clinical trials with active control groups and the use of integrated theoretical models, such as the neurovisceral integration model, are necessary to accurately delineate the causal chain underlying these effects.
Keywords:Yoga; Neuroscience; Brain Plasticity;Default Mode Network; Anxiety; Gut Microbiome; Gut–Brain Axis; Emotional Regulation.

1. Introduction

Yoga, as an ancient Indian tradition, has evolved in recent decades from a purely spiritual and physical practice into a major topic of interest in psychosomatic medicine and neuroscience. With the expansion of non-invasive neuroimaging methods and significant advances in metagenomics and epigenetics, it is now possible to assess the subtle and profound effects of yoga practices including asanas, pranayama, meditation, and Yoga Nidra—at multiple biological levels.

Despite the large body of research conducted in this field, a major gap remains in the integration of recent findings, particularly those published during the 2025–2026 period, within a unified review article. The aim of the present study is to collect, categorize, and analyze the latest findings concerning neuroplasticity, executive functions, emotional regulation, attentional networks, as well as systemic effects mediated through the gut–brain axis and gene expression.

2. Methodology (Materials and Methods)

This study was designed and conducted as a narrative review with a systematic approach. The scientific literature was searched for studies published between January 2025 and June 2026.
Search Strategy

Using Boolean operators (AND and OR), combinations of the following keywords were searched in the titles and abstracts of the articles:
“Yoga” OR “Hatha Yoga” OR “Yoga Nidra” OR “Mudra” AND “Neuroscience” OR “Neuroplasticity” OR “Prefrontal Cortex” OR “Default Mode Network” OR “fNIRS” OR “EEG” AND “Psychology” OR “Anxiety” OR “Depression” OR “Attention” OR “Cognition” AND “Microbiome” OR “Gene Expression” OR “Biomarkers”.
Inclusion and Exclusion CriteriaStudies were included in the analysis if they:
(a) employed a clinical trial, cohort study, systematic review, or scoping review design;
(b) measured neurological, psychological, cognitive, or systemic biological outcomes;
and
(c) investigated adult human populations aged 18 years or older.
Case reports, letters to the editor, and articles without full-text availability were excluded from the analysis.
Data ExtractionInformation regarding the authors, publication year, sample size, type of intervention, assessment instruments—including fMRI, fNIRS, EEG, cognitive tests, and microbial sequencing—and the main findings was extracted and thematically synthesized.

3. Results

The findings of this review were categorized into eight major subdomains.
3.1. Long-Term Effects of Yoga on Brain Structure and Executive Functions
A comprehensive scoping review published in 2025 screened 2,270 articles and selected 65 eligible studies to evaluate the effects of regular yoga practice lasting more than one year [1]. The study showed that long-term yoga practice is associated with significant structural and functional changes in the somatosensory cortex, the insula, as a center of interoception, and prefrontal regions involved in emotional regulation and executive functions.
Furthermore, among older adults, significant improvements in working memory and information-processing speed were observed. During the performance of cognitive tasks, participants also demonstrated greater neural and physiological efficiency, with lower metabolic energy expenditure.
In addition to localized structural changes, emerging evidence suggests that long-term yoga practice induces dynamic reconfiguration of brain-network topology at the whole-brain level. In other words, yoga does not merely alter the volume or thickness of specific regions; it also changes patterns of functional connectivity and the manner in which the brain transitions between different functional states, indicating profound functional plasticity at the level of neural networks [9].

3.2. Immediate Effects of a Single Yoga Session on Anxiety and Stress Contrary to the prevailing assumption that prolonged practice is necessary to produce effects, another scoping review published in 2025 examined 30 clinical trials involving a total of 1,548 participants and clearly demonstrated that even a single 30–60-minute yoga session, particularly a combination of asanas and pranayama, significantly reduces state anxiety and subjective stress markers in both healthy individuals and patients with generalized anxiety disorder (GAD) and major depressive disorder (MDD) [2].

These immediate effects were confirmed in 75% of the reviewed studies, suggesting potential clinical applications of this intervention in emergency and psychiatric settings.
3.3. Acute Neural Mechanism: Prefrontal Activation and Reduced Default Mode Network Connectivity
In a pioneering study conducted in 2025, researchers used functional near-infrared spectroscopy (fNIRS) in a naturalistic, non-laboratory setting to measure prefrontal cortex (PFC) activity during and after the performance of asana movements [3].

The findings showed that all yoga movements significantly increased hemodynamic activity in the right prefrontal cortex (P < 0.05).

Importantly, after completion of the session, a marked reduction in resting-state functional connectivity (rsFC) was observed in the left medial prefrontal cortex, which is part of the default mode network (DMN).

Given that DMN hyperactivity is directly associated with rumination and depression, this finding provides a clear biological mechanism for the antidepressant and anxiolytic effects of yoga.

3.4. Improvement of Attentional Networks in Professional Athletes A randomized controlled trial conducted in 2026 involving 92 adolescent athletes who were competitive archers, aged 12–20 years, investigated the effects of an eight-week yoga intervention on attentional networks [4].

Results from the Attention Network Test (ANT) showed that, compared with the control group, the yoga group demonstrated significant improvements in the orienting network (η² = 0.261) and the conflict-control network (η² = 0.505).

Reaction times also significantly decreased across all cue conditions and under flanker-incongruent conditions.

This study provided the first definitive evidence for the application of yoga in enhancing cognitive performance under pressure in athletes.

3.5. Physiological Effects of Yoga Nidra on Brain Waves Despite the growing popularity of Yoga Nidra (conscious sleep) in the treatment of insomnia and anxiety, a systematic review published in 2025 of electroencephalography (EEG) studies showed that evidence regarding quantitative changes in frequency bands—delta, theta, alpha, and gamma—remains fragmented and heterogeneous [5].

The authors emphasized the need for studies using standardized protocols and adequate sample sizes to reach definitive conclusions regarding the neurophysiological mechanisms of this practice.

3.6. Changes in Genetics, Lipids, and Stress Biomarkers In a three-arm randomized trial conducted in 2025, psychological indices, allostatic load, and gene expression were examined in 211 adults with chronic stress, comparing meditation, yoga, and stress-management education [6].
Although no statistically significant differences in gene expression were observed among the three groups, the yoga group alone demonstrated a significant increase in high-density lipoprotein (HDL) levels (P < 0.05), which is important for cardiovascular health.
In addition, all groups demonstrated significant within-group improvements in mental-health questionnaires.

3.7. Modulation of the Gut–Brain Axis in Alzheimer’s Disease (Key Finding)
In one of the most important studies of 2026, researchers investigated the effects of 12 weeks of daily 60-minute yoga practice in 16 patients with mild Alzheimer’s disease [7].

The clinical findings were particularly striking: Montreal Cognitive Assessment (MoCA) scores increased from 22.33 to 25.44 (P = 0.007), while Patient Health Questionnaire-9 (PHQ-9) depression scores decreased from 5.78 to 2.22 (P = 0.007).

More importantly, gut microbiome sequencing demonstrated that the composition of the intestinal microbiota shifted toward a healthier state.

Beneficial and anti-inflammatory bacteria, including Faecalibacterium prausnitzii, Bifidobacterium, and Akkermansia, increased, whereas the pro-inflammatory bacterium Collinsella aerofaciens decreased significantly.

Beta-diversity analysis showed that the overall microbial structure of the patients’ microbiome became more similar to that of the healthy control group following the intervention.

3.8. Preliminary Evidence Regarding Mudras (Hand Gestures) and CognitionA pre–post study conducted in 2026 involving 30 young women investigated the effects of performing Bhoochari Mudra for 10 minutes over five consecutive days [8].

The results of the Letter Cancellation Test (SLCT) and Digit–Letter Substitution Test (DLST) indicated significant increases in both net and total scores (P < 0.001), without any observed increase in errors.

In other words, information-processing speed increased without a decline in accuracy.
Although the absence of a control group and the small sample size mean that these findings require replication in future studies, they nevertheless open a new avenue for investigating the cognitive effects of subtle hand movements.

4. Discussion

The findings synthesized in this review indicate that yoga is not merely a low-intensity physical activity; rather, it is a complex, multidimensional intervention that simultaneously affects neural, cognitive, psychological, and microbial levels.

A relative consensus among the studies concerns the key role of the prefrontal cortex and the default mode network (DMN). Activation of the right prefrontal cortex during asanas [3] is likely associated with increased focused attention and cognitive control, whereas reduced functional connectivity within the DMN following practice [3] indicates reduced self-referential thought and rumination, which are considered core features of many mood disorders.This finding is fully consistent with the results of reviews concerning anxiety [2] and depression [7].
On the other hand, the discovery of an association between yoga and changes in gut microbiome composition in patients with Alzheimer’s disease [7] represents a potentially transformative development in our understanding of the underlying mechanisms.

The gut–brain axis, through the vagus nerve and microbial metabolites such as short-chain fatty acids (SCFAs), can modulate neuroinflammation and increase the expression of neurotrophic factors such as brain-derived neurotrophic factor (BDNF), potentially providing an explanation for the improvement in cognitive function observed in these patients.

Similarly, the findings concerning increased HDL [6] indicate beneficial effects of yoga on metabolism and vascular health, which may indirectly support brain health.
Nevertheless, the present review has several limitations. There is considerable clinical heterogeneity in the types of interventions, including differences in yoga style, duration, intensity, and composition, as well as variation in assessment instruments and target populations. These
factors pose challenges to the generalizability of the findings.In particular, the evidence concerning Yoga Nidra [5] and mudras [8] remains at an early stage. Future studies are recommended to employ stronger theoretical models, such as the Neurovisceral Integration Model, and to simultaneously use neuroimaging, peripheral biomarkers, and metagenomics in order to clearly delineate the causal chain linking changes in the brain, microbial alterations, and clinical outcomes.

5. Conclusion

Based on the most recent scientific evidence published in 2025 and 2026, yoga can be regarded as an effective and low-cost non-pharmacological intervention with three principal levels of action:
Neural level: Increased prefrontal cortical activity and modulation of the default mode network.
Psychological and cognitive level: Acute and long-term reductions in anxiety, depression, and stress, accompanied by improvements in attention and memory.

Systemic level: Modulation of the gut–brain axis and alteration of gut microbiome composition toward an anti-inflammatory state.

Despite these promising findings, high-quality clinical trials with active control groups and long-term follow-up are essential before yoga can be incorporated into mainstream therapeutic approaches in psychiatry and neurology.

6. References

[1] Long-term effects of yoga-based practices on neural, cognitive, psychological, and physiological outcomes in adults: a scoping review and evidence map. BMC Complementary Medicine and Therapies, 2025, 25:92.

[2] Ikai-Tani S, Kamiyama S, Tani H, Sabiston CM. A single yoga session for anxiety and stress in adults with or without mental illnesses: A scoping review. International Journal of Neuropsychopharmacology, 2025, 28(Supplement_2): ii.93.

[3] Goodrick M, et al. Yoga Asana Increases Prefrontal Cortex Activity and Reduces Resting-State Functional Connectivity. Complementary Medicine Research, 2025.

[4] Baishya A, et al. Effects of Yoga on the Efficiency of the Attentional Networks in Competitive Archers: A Randomized Controlled Trial. International Journal of Yoga, 2026, 19(1): 85–93.
[5] Kachera V, et al. The Effects of Yoga Nidra Practice on EEG Oscillations: A Systematic Review. medRxiv, 2025.

[6] Denninger JW, et al. Psychological assessments, allostatic load and gene expression analyses in a randomized controlled trial comparing meditation, yoga, and stress education. Frontiers in Psychology, 2025.

[7] Tiwari P, et al. Association of yoga with cognitive and gut microbiome changes in Alzheimer’s disease: An exploratory case-control study. Journal of Alzheimer’s Disease, 2026.

[8] Impact of Bhoochari Mudra on cognitive functions among naïve yoga practitioners: A single group pre–post study. Journal of Integrative Medicine, ScienceDirect (Pre-print), 2026.

[9] Interconnections and global transitions among functional states encode activity-related dynamics as brain topology changes after yoga training. Scientific Reports, 2025, 15:16845.