Changes in P300 following alternate nostril yoga breathing and breath awareness

Effectiveness of Alternative Nostril Breathing on Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

INTRODUCTION

Hypertension, a significant risk factor for cardiovascular disease, has a high prevalence rate globally. While drug use is the most common approach, lifestyle improvements are crucial. Recently, there has been a notable upsurge of interest in various breathing methods, including device-induced breathing techniques like Resperate. However, the reliance on a device for these techniques has prompted the popularity of alternative breathing methods that can be performed without any external devices. One such method that has gained significant attention is alternative nostril breathing, which serves as an alternative medical treatment known for its effectiveness in reducing blood pressure. Therefore, this study aimed to systematically investigate the therapeutic effects of alternate nostril breathing.

METHODS

We selected 16 articles published in English, Korean, and Chinese databases, of which 14 met the eligibility criteria, and a systematic literature review was conducted. A meta-analysis was conducted on six qualified studies. Meta and sensitivity analyses were conducted using a random effects model of six randomized clinical trials (RCTs).

RESULTS

Results of alternative nostril breathing (ANB) on 1,377 participants have been reported based on the effects of systolic and diastolic blood pressure (SBP and DBP). Both the lone ANB and combined yoga programs resulted in significant reductions in SBP and DBP. Meta-analysis of the 6 trials with 525 participants demonstrated that ANB was better in reducing SBP than that of the control group (nonintervention or placebo) (mean difference [MD]: -7.16, 95% confidence interval [CI]: -7.86 to -6.45, I2: 93%). Moreover, ANB was better in reducing DBP than that of the control group (nonintervention or placebo) (MD: -5.16, 95% CI: -5.89 to -4.44, I2: 87%).

CONCLUSION

The results of the study are valid; however, attention is needed when interpreting the results because the heterogeneity exceeds 75%. A systematic review of 14 studies found that ANB can improve cardiovascular indicators, such as SBP and DBP, as well as non-cardiovascular factors, such as fatigue, intraocular pressure, and memory. However, the review noted that implementing double blinding in studies on yoga breathing intervention is difficult, and most studies were not double-blinded, suggesting the need for high-quality RCTs in the future.

Visual respiratory biofeedback to improve visuospatial cognition and cardiac interoception in migraineurs: a study protocol for a randomized controlled trial

Objectives

Migraine is a complex neurological disorder that typically presents with unilateral cephalgia associated with cognitive impairment and reduced interoception. These symptoms result in socio-economic repercussions due to reduced productivity, efficiency, and work performance. Therefore, along with headache management, improving cognition and interoception should also be significant therapeutic targets to effectively manage migraine. To achieve this, we propose to explore the role of a yoga-based visual respiratory biofeedback (VRB) as a possible therapeutic strategy.

Methods and analysis

At least 64 participants will be recruited for the trial after screening for eligibility criteria, using the migraine screening questionnaire and Montreal cognitive assessment test. They will be randomly allocated (1:1) to either the experimental group receiving a 20-min session of yoga-based VRB or the control group who will be asked to watch a documentary film for the same duration. Visuospatial cognition will be assessed by the Corsi block-tapping task, and cardiac interoceptive accuracy will be assessed by the heartbeat counting task at baseline and immediately after the intervention. Based on the distribution and variance of the data obtained, analysis will be conducted based on linear mixed models using SPSS version 28.0.1.0, with a two-sided p-value of < 0.05 considered to be statistically significant.

Discussion

To the best of our knowledge, this is the first study to design and assess the effects of yoga-based biofeedback therapy on cognition and cardiac interoception in migraineurs. Furthermore, we postulated that pranayama's therapeutic effects might be enhanced by using visual yogic respiratory biofeedback. Considering the socio-economic burden of migraine, if found effective, VRB investigated in the trial could be considered as a therapeutic strategy.

Clinical trial registration

ClinicalTrials.gov CTRI, CTRI/2023/03/050430.

P300 Following Four Voluntarily Regulated Yoga Breathing Practices and Breath Awareness

Attention was influenced by yoga breathing in previously published research. Each yoga breathing practice uniquely modifies specific breath characteristics. Differences in the study designs, assessment methods and interventions resulted in difficulty in comparing effects between yoga breathing practices. This study aimed (i) to compare four yoga breathing practices on attention using an auditory oddball task and (ii) to determine cardiac autonomic activity associated with attention using heart rate variability. P300 event related potential was recorded simultaneously with heart rate variability before and after 18-minute periods each of (i) high frequency yoga breathing (with increased breath frequency), (ii) bellows yoga breathing (with increased depth of respiration), (iii) alternate nostril yoga breathing (with alternate nostril patency), (iv) bumblebee yoga breathing (with prolonged exhale), (v) breath awareness (with attention to the breath) and (vi) quiet seated rest as control in 38 yoga experienced males (average age ± SD; 24.08 ± 4.01 years). The six sessions were on separate, randomly allocated days. The P300 peak amplitude recorded at Pz was significantly increased after four yoga breathing practices (Bonferroni adjusted post-hoc tests, repeated measures ANOVA). No significant changes were noted in heart rate variability following yoga breathing or control sessions. These findings suggest that the four yoga breathing practices increase the attentional neural resources engaged for this auditory oddball task, irrespective of the characteristic of breath uniquely regulated in the four yoga breathing practices.

Effect of alternate nostril breathing on evoked potentials among internet addicts

Increased availability of smartphones and easy access to the internet among adolescents has resulted in Internet Addiction (IA). Effects of IA and Pranayama on evoked potential are available but studies on the comparison of immediate and 6-week effects of alternate nostril breathing on evoked potentials among medicos with internet addiction are not available as per our search in PubMed, hence the study was chosen. In this comparative study 100 male and female medical students aged between 18-25 years, with internet addiction scores ≥ 50 were included as study participants. P300 auditory event-related potential and pattern reversal visual evoked potential (VEP) were recorded before, immediately, and 6 weeks after practicing pranayama. Repeated measure ANOVA shows statistically significant change (P<0.05) in P300 amplitude, P100 latency, N145 latency, and VEP amplitude. The post hoc Bonferroni test shows that P100 latency and N145 latency significantly reduced immediately after 15 minutes of pranayama. P300 amplitude and VEP amplitude significantly increased only after practicing pranayama for 6 weeks. Pranayama has an immediate effect on latency, but it takes 6 weeks of practice to significantly change amplitude.

Slow yoga breathing improves mental load in working memory performance and cardiac activity among yoga practitioners

This study investigated the immediate effect of slow yoga breathing (SYB) at 6 breaths per minute (bpm) simultaneously on working memory performance and heart rate variability (HRV) in yoga practitioners. A total of 40 healthy male volunteers performed a working memory task, ‘n-back’, consisting of three levels of difficulty, 0-back, 1-back, and 2-back, separately, before and after three SYB sessions on different days. The SYB sessions included alternate nostril breathing (ANB), right nostril breathing (RNB), and breath awareness (BAW). Repeated measures analysis of variance showed a significant reduction in reaction time (ms) in 2-back condition immediately after ANB (−8%), RNB (−8%) and BAW (−5%) practices. Similarly, the accuracy was improved in the 0-back condition after RNB (4%), and in the 2-back condition after ANB (6%) and RNB (6%) practices. These results suggest that SYB practice enhances cognitive abilities (8–9%) related to memory load and improves the functioning of cardiac autonomic activity, which is required for the successful completion of mental tasks.Trial registered in the Clinical Trials Registry of India (CTRI/2018/01/011132).

Effects of Hatha yoga on cognitive functions in the elderly: a cross-sectional study

This study aimed to investigate the effects of Hatha yoga practice on cognitive functions in the elderly. Thirty healthy older men participated in this study. They belonged to 2 groups. The first group included 15 Hatha yoga practitioners for at least 2 years. The control group involved 15 male older adults who shared the same characteristics (age, years of formal education, and level of physical activity) as the Hatha yoga group but were naive to yoga, meditation, or any mind-body intervention. Neuropsychological tests were applied to measure selective attention, sustained attention, episodic memory, and processing speed. The following tests were administered: The French adaptation of the Victoria Stroop test, the Zazzo's Cancellation Task, the Five Word Test, and a battery of computerized tests to evaluate reaction time. Long-term Hatha yoga practice showed promising results related to executive functions and reaction time, but no significant difference was found between the two groups in episodic memory and sustained attention although a trend of improvement was observed in favor of Hatha yoga practitioners. In conclusion, long-term Hatha yoga practitioners have better cognitive abilities compared to the control group in certain aspects of cognitive functions. Further physiological and psychological variables need to be examined in order to highlight the correlation between yoga intervention and cognitive performance.

P300 cognitive assessment in patients with first-episode psychosis: a prospective case-control study

Background

Several studies using event-related potential (ERP) methods have reported a relationship between the cognitive dysfunction of patients with psychosis and P300 latency and amplitude. P300 follow-up studies in patients with schizophrenia receiving antipsychotic treatment revealed that the P300 amplitudes were increased while other studies showed limited changes in the P300 amplitude even after antipsychotics use.

Results

We found that at the first presentation, all patients’ groups have significantly lower amplitude and more prolonged latency of P300 than controls. All the first-episode psychosis patients showed a significant improvement of P300 amplitude mean scores after 1 year, but with no significant change in the P300 latency. There was an inverse correlation between the patients’ PANSS scores and their P300 latency and amplitude values.

Conclusion

P300 amplitude and latency might be of clinical value in the evaluation of cognitive functions in the first-episode psychosis patients. The abnormalities in P300 may be improved with continuous control of psychotic symptoms with psychotropic medications.

Effect of Moola Bandha (Perineum Contraction), A Yogic Lock on Cognitive Functions of College Students: An Exploratory Study

Academic performance and excellence of college students are mainly depending on their cognitive functions. The purpose of this study was to examine the effectiveness of a yogic lock or hold, Moola bandha (perineum contraction) on cognitive functions of teacher training college students. Twenty-three healthy volunteers with the mean ± standard deviation age of 21.96 ± 1.64 years were recruited from a district institute of education and training (DIET) college, North India. All the subjects were asked to perform Moola bandha for the duration of 30 min a day (15 min in the morning and 15 min in the evening) for a period of 30 days. Assessments were taken before and after the intervention period. Results of this study showed a significant increase in the scores of d2 attention total number, digits span forward and backward test, Stroop tasks (neutral total and correct, congruent total and correct, and incongruent correct), and self-control scale along with a significant reduction in d2 attention (omission, commission, and timings), trail making text A and B duration, and positive and negative affective schedule's negative affect scores compared with its respective baseline. These results suggest that 30 min of daily practice of Moola bandha for 30 days is effective in improving the cognitive functions of teacher training college students.

Deep slow nasal respiration with tight lip closure for immediate attenuation of severe tics

BACKGROUND

Severe intractable tics, which are associated with Tourette syndrome and chronic tic disorder (TS/CTD), severely affect the quality of life. Common less-invasive treatments are often unable to attenuate tics with deep brain stimulation currently being the only effective treatment. We aimed to assess the anti-tic effect of deep slow nasal respiration with tight lip closure using patients with TS/CTD.

METHODS

We retrospectively analyzed 10 consecutive patients (9 men, 1 woman; 23-41 years old). We instructed the patients to perform the procedure for 120 s and to obtain a video recording of before and during the procedure. The videos were used to count tics and determine lip competency or incompetency. The counted tics were rated using the modified Rush Video Rating Scale.

RESULTS

Compared with before the procedure, there were significantly lower frequencies of motor and phonic tics, as well as video scored, during the procedure. Eight patients presented with lip incompetency before the procedure and none after the procedure (P = 0.041). There were no side effects associated with the procedure.

CONCLUSION

Our findings indicate that deep slow nasal respiration with tight lip closure ameliorates tics in patients with TS/CTD. In accordance with our results, lip opening and oral breathing could be causes of tics, in addition to heritability. Therefore, this novel procedure could improve tics. Furthermore, our findings could contribute toward the development of tic treatments and elucidate their pathophysiology regarding the reward system, hypersensitivity, autonomic nerves, and nasal airway.

Effect of Unilateral Left Nostril Breathing (Chandra Anga Pranayama) on Cognitive Function in Healthy Yoga-Naïve Individuals: A Randomized, Controlled, Pilot Study

INTRODUCTION

Breathing modulates cortical neuronal activity. Various breathing exercises are purported to have specific effects on emotional and cognitive functions.

OBJECTIVE

To determine the effect of unilateral left nostril breathing (ULNB) on nonlateralized, overall cognitive functions using computerized psychometric tests.

METHODS

A randomized, controlled, pilot study was conducted among 20 healthy yoga-naïve medical students. ULNB was performed for 15 min by the test group (n = 10) and breath awareness by the control group (n = 10). Attention and processing speed, memory, and executive function were assessed using the Letter-Digit Substitution Test, Sternberg Memory Task, and Victoria Stroop Test, respectively. Baseline, pre- and postintervention scores were recorded.

RESULTS

There was no significant difference between the groups in baseline scores. In the Sternberg Memory Task, a statistically significant decrease in response time was seen in the test (t(9) = 3.855, p = 0.004) as well as the control group (t(9) = 3.120, p = 0.012); there was no significant difference between the groups. No significant effect of UNLB was seen in the Letter-Digit Substitution Test and Stroop Test.

CONCLUSIONS

Our study showed no difference in the effects of 15-min practice of ULNB and breath awareness on cognitive functions; both improved memory but not attention or executive function.

Role of Yoga and Meditation as Complimentary Therapeutic Regime for Stress-Related Neuropsychiatric Disorders: Utilization of Brain Waves Activity as Novel Tool

During recent decades, stress-related neuropsychiatric disorders such as anxiety, depression, chronic tension headache, and migraine have established their stronghold in the lives of a vast number of people worldwide. In order to address this global phenomenon, intensive studies have been carried out leading to the advancement of drugs like anti-depressants, anxiolytics, and analgesics which although help in combating the symptoms of such disorders but also create long-term side effects. Thus, as an alternative to such clinical practices, various complementary therapies such as yoga and meditation have been proved to be effective in alleviating the causes and symptoms of different neuropsychiatric disorders. The role of altered brain waves in this context has been recognized and needs to be pursued at the highest level. Thus, the current study provides a review focused on describing the effects of yoga and meditation on anxiety and depression as well as exploring brain waves as a tool for assessing the potential of these complementary therapies for such disorders.

Changes in Shape and Size Discrimination and State Anxiety After Alternate-Nostril Yoga Breathing and Breath Awareness in One Session Each

BACKGROUND Yoga breathing techniques like high-frequency yoga breathing (HFYB) and breath awareness (BAW) have been associated with improved performance in the shape and size discrimination task. A PubMed search of the literature revealed that alternate-nostril breathing has been shown to improve performance in attention tasks, but the effect on tactile perception has not been studied. Hence, the present study was designed to assess the immediate effects of alternate-nostril yoga breathing (ANYB) compared to breath awareness on shape and size discrimination and state anxiety. MATERIAL AND METHODS Fifty healthy male volunteers ages 20-50 years (group mean ±S.D., 28.4±8.2 years) were recruited. Each participant was assessed in 3 sessions conducted on 3 separate days at the same time of day. The 3 sessions were (i) alternate-nostril yoga breathing (ANYB), (ii) breath awareness (BAW), and (iii) quiet sitting (QS), and the sequence of the sessions was randomly allocated. The shape and size discrimination task and state anxiety were assessed before and after all 3 sessions. Repeated measures analysis of variance (RM-ANOVA) followed by post hoc tests for multiple comparisons, which were Bonferroni-adjusted, were performed to compare data before and after all 3 sessions using SPSS version 18.0. RESULTS The errors scores in the shape and size discrimination task showed a significant reduction after the ANYB session (p<0.001). A significant reduction was found in the level of state anxiety after breath awareness (p<0.05) and quiet sitting sessions (p<0.001). CONCLUSIONS The present results suggest that ANYB: (i) improves performance in a task which requires perceptual sensitivity and focused attention, but (ii) does not reduce state anxiety following this task.

Effects of 8 weeks of modified hatha yoga training on resting-state brain activity and the p300 ERP in patients with physical disability-related stress

[Purpose] We examined the effects of Hatha yoga on EEG and ERP in patients with physical disability-related stress. [Participants and Methods] Eighteen male and female injured workers with high stress levels, aged between 18 to 55 years, were evenly divided into two groups: untrained (CG) and trained (TG) modified hatha yoga groups. A modified Hatha yoga protocol was designed for this population by two certified yoga instructors, approved by a physical therapist, and conducted for one hour, three times weekly for 8 weeks. [Results] The results indicated a significant increase in alpha EEG activity over the frontal, central, and parietal electrodes and the delta EEG activity over the centroparietal electrode from pre- to post-training in TG. In addition, significantly faster auditory reaction time for target stimuli, as well as lower P300 peak latency of ERP in auditory oddball paradigm were obtained in TG after 8 weeks of yoga training compare to CG. [Conclusion] Changes in brain activity and ERP components following yoga training would support the psychophysiological effects of hatha yoga as an adjunct to routine rehabilitation.

The effect of movement-focused and breath-focused yoga practice on stress parameters and sustained attention: A randomized controlled pilot study

Yoga-based practices (YBP) typically involve a combination of movement sequences, conscious regulation of the breath, and techniques to engage attention. However, little is known about whether effects of YBP result from the synergistic combination of these components, or whether a subset may yield similar effects. In this study we compared the effect of a movement-focused practice and a breath-focused practice on stress parameters (perceived stress and salivary cortisol) and sustained attention (response inhibition) in yoga naïve university students. While participants of both programs showed a reduction in perceived stress and salivary cortisol, only the breath-focused group showed improvements in sustained attention. In addition, improvement in sustained attention was correlated with reduction in perceived stress but not with reduction in salivary cortisol. We discuss these findings in the context of a theoretical framework outlining bottom-up neurophysiological and top-down neurocognitive mechanisms hypothesized to be engaged by YBP.

Effect of Alternate Nostril Breathing Exercise on Experimentally Induced Anxiety in Healthy Volunteers Using the Simulated Public Speaking Model: A Randomized Controlled Pilot Study

A randomized controlled pilot study was carried out to determine the effect of a 15-minute practice of ANB exercise on experimentally induced anxiety using the simulated public speaking model in yoga-naïve healthy young adults. Thirty consenting medical students were equally divided into test and control groups. The test group performed alternate nostril breathing exercise for 15 minutes, while the control group sat in a quiet room before participating in the simulated public speaking test (SPST). Visual Analog Mood Scale and Self-Statements during Public Speaking scale were used to measure the mood state at different phases of the SPST. The psychometric scores of both groups were comparable at baseline. Repeated-measures ANOVA showed a significant effect of phase (p < 0.05), but group and gender did not have statistically significant influence on the mean anxiety scores. However, the test group showed a trend towards lower mean scores for the anxiety factor when compared with the control group. Considering the limitations of this pilot study and the trend seen towards lower anxiety in the test group, alternate nostril breathing may have potential anxiolytic effect in acute stressful situations. A study with larger sample size is therefore warranted. This trial is registered with CTRI/2014/03/004460.

Immediate Effects of Yoga Breathing with Intermittent Breath Holding on Response Inhibition among Healthy Volunteers

Background:

There is very little evidence available on the effects of yoga-based breathing practices on response inhibition. The current study used stop-signal paradigm to assess the effects of yoga breathing with intermittent breath holding (YBH) on response inhibition among healthy volunteers.

Materials and Methods:

Thirty-six healthy volunteers (17 males + 19 females), with mean age of 20.31 ± 3.48 years from a university, were recruited in a within-subject repeated measures (RM) design. The recordings for stop signal task were performed on three different days for baseline, post-YBH, and post yogic breath awareness (YBA) sessions. Stop-signal reaction time (SSRT), mean reaction time to go stimuli (go RT), and the probability of responding on-stop signal trials (p [r/s]) were analyzed for 36 volunteers using RM analysis of variance.

Results:

SSRT reduced significantly in both YBH (218.33 ± 38.38) and YBA (213.15 ± 37.29) groups when compared to baseline (231.98 ± 29.54). No significant changes were observed in go RT and p (r/s). Further, the changes in SSRT were not significantly different among YBH and YBA groups.

Conclusion:

Both YBH and YBA groups were found to enhance response inhibition in the stop-signal paradigm. YBH could be further evaluated in clinical settings for conditions where response inhibition is altered.

Effects of yogic breath regulation: A narrative review of scientific evidence

Pranayama or breath regulation is considered as an essential component of Yoga, which is said to influence the physiological systems. We present a comprehensive overview of scientific literature in the field of yogic breathing. We searched PubMed, PubMed Central and IndMed for citations for keywords “Pranayama” and “Yogic Breathing”. The search yielded a total of 1400 references. Experimental papers, case studies and case series in English, revealing the effects of yogic breathing were included in the review. The preponderance of literature points to beneficial effects of yogic breathing techniques in both physiological and clinical setups. Advantageous effects of yogic breathing on the neurocognitive, psychophysiological, respiratory, biochemical and metabolic functions in healthy individuals were elicited. They were also found useful in management of various clinical conditions. Overall, yogic breathing could be considered safe, when practiced under guidance of a trained teacher. Considering the positive effects of yogic breathing, further large scale studies with rigorous designs to understand the mechanisms involved with yogic breathing are warranted.

Changes in Reaction Time after Yoga Bellows-type Breathing in Healthy Female Volunteers

Background

Previously, yoga bellows-type breathing (bhastrika pranayama) reduced reaction time (RT) or reduced anticipatory responses in male participants or a mixed group of male and female participants.

Aims

The present study as a control trial aimed to assess the effects of yoga bellows-type breathing on RT in females exclusively.

Methods

The sample consisted of 25 healthy females, aged between 19 and 32 years (group mean ± standard deviation, 22.8 ± 3.5 years). All of them had prior minimum experience of yoga including yoga bellows-type breathing of 12 months. The RT was assessed in each participant before and after three randomized sessions differed in the intervention given held on three separate days. The sessions were (i) YOGA bellows-type breathing or bhastrika pranayama(BHK), (ii) Breath awareness (BAW), and (iii) Sitting quietly (CTL) as a control session. The duration of the intervention was 18 min, and the participants were assessed for RT before and after the intervention.

Results

Repeated measures ANOVA, post hoc tests with Bonferroni adjusted showed that the time taken to obtain a correct response reduced significantly after 18 min of BAW (P < 0.05) and CTL (P < 0.05). However, no changes were seen in the RT after BHK.

Conclusions

The results suggest that different interventions may optimize performance in tasks requiring attention in females compared to males.

Hypoxia in CNS Pathologies: Emerging Role of miRNA-Based Neurotherapeutics and Yoga Based Alternative Therapies

Cellular respiration is a vital process for the existence of life. Any condition that results in deprivation of oxygen (also termed as hypoxia) may eventually lead to deleterious effects on the functioning of tissues. Brain being the highest consumer of oxygen is prone to increased risk of hypoxia-induced neurological insults. This in turn has been associated with many diseases of central nervous system (CNS) such as stroke, Alzheimer's, encephalopathy etc. Although several studies have investigated the pathophysiological mechanisms underlying ischemic/hypoxic CNS diseases, the knowledge about protective therapeutic strategies to ameliorate the affected neuronal cells is meager. This has augmented the need to improve our understanding of the hypoxic and ischemic events occurring in the brain and identify novel and alternate treatment modalities for such insults. MicroRNA (miRNAs), small non-coding RNA molecules, have recently emerged as potential neuroprotective agents as well as targets, under hypoxic conditions. These 18-22 nucleotide long RNA molecules are profusely present in brain and other organs and function as gene regulators by cleaving and silencing the gene expression. In brain, these are known to be involved in neuronal differentiation and plasticity. Therefore, targeting miRNA expression represents a novel therapeutic approach to intercede against hypoxic and ischemic brain injury. In the first part of this review, we will discuss the neurophysiological changes caused as a result of hypoxia, followed by the contribution of hypoxia in the neurodegenerative diseases. Secondly, we will provide recent updates and insights into the roles of miRNA in the regulation of genes in oxygen and glucose deprived brain in association with circadian rhythms and how these can be targeted as neuroprotective agents for CNS injuries. Finally, we will emphasize on alternate breathing or yogic interventions to overcome the hypoxia associated anomalies that could ultimately lead to improvement in cerebral perfusion.

Yoga and heart rate variability: A comprehensive review of the literature

Heart rate variability (HRV) has been used as a proxy for health and fitness and indicator of autonomic regulation and therefore, appears well placed to assess the changes occurring with mind.-body practices that facilitate autonomic balance. While many studies suggest that yoga influences HRV, such studies have not been systematically reviewed. We aimed to systematically review all published papers that report on yoga practices and HRV. A comprehensive search of multiple databases was conducted and all studies that reported a measure of HRV associated with any yoga practice were included. Studies were categorized by the study design and type of yoga practice. A total of 59 studies were reviewed involving a total of 2358 participants. Most studies were performed in India on relatively small numbers of healthy male yoga practitioners during a single laboratory session. Of the reviewed studies, 15 were randomized controlled trials with 6 having a Jadad score of 3. The reviewed studies suggest that yoga can affect cardiac autonomic regulation with increased HRV and vagal dominance during yoga practices. Regular yoga practitioners were also found to have increased vagal tone at rest compared to non-yoga practitioners. It is premature to draw any firm conclusions about yoga and HRV as most studies were of poor quality, with small sample sizes and insufficient reporting of study design and statistical methods. Rigorous studies with detailed reporting of yoga practices and any corresponding changes in respiration are required to determine the effect of yoga on HRV.

P300 aberration in first-episode schizophrenia patients: a meta-analysis

BACKGROUND

Decreased P300 amplitude is one of the most consistent findings in patients with schizophrenia. However, whether prolonged P300 latency occurs in patients with schizophrenia, especially first-episode schizophrenia (FES) patients, remains controversial.

METHODS

A meta-analyses of P300 aberration in FES patients and healthy control(HC) group was conducted. The meta-regression analysis was performed using a random effects model. The pooled standardized effect size (PSES) was calculated as the division of the difference between the means of the two groups by the common standard deviation.

RESULTS

A total of 569 FES patients and 747 HCs were included in this meta-analysis. P300 amplitude was significantly reduced (PSES = -0.83, 95% CI: -1.02-0.65, P = 0.00001) and P300 latency was delayed significantly in FES patients (PSES = -0.48, 95% CI: 0.14-0.81, P = 0.005). The meta-regression analysis showed that task difficulty was a source of heterogeneity.

CONCLUSIONS

The meta-analysis confirms that disrupted information processing is found in FES patients, which is manifested by smaller P300 amplitude and delayed P300 latency.