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Does vagal nerve stimulation explain mind-body interventions?

13 Mar

In yoga, pranayama means breath regulation, and refers to a set of breathing techniques. The always interesting Dr. Greger has posted a video suggesting that the effects of breathing on the vagus nerve may explain the effectiveness of yogic pranayama and other mind body interventions.

Why you need to read the original research: neti pot edition

20 Jan

The last few days I have been suffering from a cold. In order to help relieve my sinuses, I have resorted to a traditional Indian nasal irrigation technique: the neti pot. I know that it sounds gross, but there is evidence that the practice has modest benefits.

But what to make of this claim, I found at the web site University Health News

Try finding Dead Sea salt; studies show that Dead Sea salt seems to confer some added benefit over regular saline solutions, as it likely has particularly effective anti-inflammatory effects.

This struck me as odd, since all salt is composed of sodium chloride, it seemed unlikely that Dead Sea salt could be different enough to have any detectable difference. Fortunately, Unitersity Health News did cite a source for this claim: a paper titled: “Dead Sea salt irrigations vs saline irrigations with nasal steroids for symptomatic treatment of chronic rhinosinusitis: a randomized, prospective double-blind study”

I was delighted to learn that there the researchers used an outcome measure called the Sino-Nasal Outcomes Test 20, or SNOT 20 for short.

The study reported:

The 2 groups were homogeneous with respect to pretreatment primary and secondary outcome metrics. Dropout rates were 30% in the DSS group and 36.6% in the control group. Both groups showed significant improvement in mean SNOT-20 scores following treatment; however, the degree of improvement was not significantly different between groups (p = 0.082). There were no significant changes in secondary outcome metrics between the 2 groups

In other words, the study found no advantage for Dead Sea salt, the opposite of what was reported by University Health News. It pays to check out the original research and not assume that media reports are accurate.

By the way, exactly which University is University Health News affiliated? Turns out they are not connected to any.

How our ancestors exercised (evidence against too much sitting)

30 Nov

From this weekend’s New York Times:

Are we fighting thousands of years of evolutionary history and the best interests of our bodies when we sit all day?That question is at the core of a fascinating new study of the daily lives and cardiovascular health of a modern tribe of hunter-gatherers. The findings strongly suggest that we are born to be in motion, with health consequences when we are not

You can read the abstract of the original research here.

I do yoga and the 10,000 steps a day program.

Nike not Emerson

3 Aug

I just received an email from a yoga study with this quotation:

“The only person you are destined to become is the person you decide to be.” ― Ralph Waldo Emerson

Does that really sound like Emerson? A little internet searching turns up the real source, a 1991 Nike advertisement.

Here are some of Emerson’s actual words:

“Man is timid and apologetic; he is no longer upright; he dares not say ‘I think,’ ‘I am,’ but quotes some saint or sage.”

 

Flaw in the yoga -cognitive impairment study

29 Jul

On Wednesday, I blogged about a new study of the effects of yoga on cognitive impairment. Thinking it over, I realized that some of the study’s results rest on a serious methodological flaw.

The study compares measures before the intervention to measures after the intervention within in each group. For example, it looks at the Geriatric Depression Scale scores for the yoga group before and after the intervention and says that there is a statistically significant difference. But this is not the correct analysis, we want to compare the changes between the yoga group and the control group. An appropriate procedure would have been a gain score analysis. The authors could have subtracted the after treatment scores from the before treatment scores and then compared those two values using an appropriate statistical test.

In the other words, the study had the possibility of comparing the control and the experimental group but failed to so. All it really says it that the scores improved in the treatment group. That is an interesting finding, but it should be considered only exploratory and suggestive. I have no objection to publishing exploratory findings, I have done so myself. But the authors had the opportunity to make a better test and they failed to do so.

Yoga may reduce mild cognitive impairment

27 Jul

Let me state my biases right upfront, I am a yoga practitioner, so I may have a tendency to be less critical of yoga positive research. With that in mind, let me report on this study published in The Journal of Alzheimer’s Disease: “Changes in Neural Connectivity and Memory Following a Yoga Intervention for Older Adults: A Pilot Study.” Here is the abstract:

BACKGROUND:
No study has explored the effect of yoga on cognitive decline and resting-state functional connectivity.

OBJECTIVES:
This study explored the relationship between performance on memory tests and resting-state functional connectivity before and after a yoga intervention versus active control for subjects with mild cognitive impairment (MCI).

METHODS:
Participants ( ≥ 55 y) with MCI were randomized to receive a yoga intervention or active “gold-standard” control (i.e., memory enhancement training (MET)) for 12 weeks. Resting-state functional magnetic resonance imaging was used to map correlations between brain networks and memory performance changes over time. Default mode networks (DMN), language and superior parietal networks were chosen as networks of interest to analyze the association with changes in verbal and visuospatial memory performance.

RESULTS:
Fourteen yoga and 11 MET participants completed the study. The yoga group demonstrated a statistically significant improvement in depression and visuospatial memory. We observed improved verbal memory performance correlated with increased connectivity between the DMN and frontal medial cortex, pregenual anterior cingulate cortex, right middle frontal cortex, posterior cingulate cortex, and left lateral occipital cortex. Improved verbal memory performance positively correlated with increased connectivity between the language processing network and the left inferior frontal gyrus. Improved visuospatial memory performance correlated inversely with connectivity between the superior parietal network and the medial parietal cortex.

CONCLUSION:
Yoga may be as effective as MET in improving functional connectivity in relation to verbal memory performance. These findings should be confirmed in larger prospective studies.

Interesting, but I do have a few concerns. The improvement in depression for the yoga group was statistically significant but the effect size was small:

the yoga group improved significantly in depression (GDS) and in visuospatial memory (Rey-O delayed recall). The clinical improvement in GDS for the yoga group was only minimal (baseline 7.5 (5.1) and follow up 3.9 (2.5); p = 0.01).

If you look at the table you will see that the control group also experience a reduction in depression, the fact that it did not achieve significant is likely an artifact of the study’s small sample size. Moreover, the yoga group started out with much higher depression scores suggesting that the groups might not have been comparable.

Here is the authors’ descriptions of the study’s limitations:

The sample size was only powered towards rs-fMRI findings, and exploring relationships between memory and functional connectivity, not exploring multi-domain effects on cognition. Additionally, we do not have long-term follow-up, which means we are unable to explore cognitive decline towards dementia. Also, it is possible that the enhanced cognitive benefits and connectivity changes resulting from the KK yogic intervention were due to the 60 min of instruction per week, the 12 min per day of Kirtan kriya meditation (shown to positively affect blood flow in the brain [34]), or a combination of these factors. However, as previous studies only using KK meditation found activation patterns that are in-line with those from the present research, it is unlikely that the weekly classes presented a large deviation. Nevertheless, this is a fruitful area for future research studies, which may aim to parse out the effects of these various activities, or perhaps determine that for optimal benefits weekly classes in addition to a daily meditative practice is recommended.

 

Does Superbrain Yoga work?

11 Jan

Claims about the benefits of Superbrain yoga are all over the Internet.  For example, take a look at this video:

 


or this one:


But does it really work?

That is a question my colleague Kathy Little and I posed in our paper “Two studies of Superbrain Yoga’s potential effect on academic performance based on the Number Facility Test.”

Here is the abstract:

“Superbrain Yoga is an exercise that involves squatting while holding the ear lobes with controlled breathing. Advocates claim that this exercise improves cognition and academic performance. This study tested the ability of Superbrain Yoga to improve performance on a cognitive task called the Number Facility Test. In the first experiment, 30 adults completed a baseline version of the Number Facility Test; performed standard squats, Superbrain Yoga, and a rest trial (counterbalanced); and were re-administered the Number Facility Test after each task. A nonparametric Quade test showed no significant difference in outcome measures (p = .99, Kendall’s W = .005). In the second experiment, 30 adults completed a baseline version of the Number Facility Test, performed standard squats and 2 alternative forms of Superbrain Yoga (counterbalanced), and were re-administered the Number Facility Test after each task. A Quade test indicated no significant difference in outcome measures (p = .19, Kendall’s W = .086). These results provide no support for the claims made for Superbrain Yoga. However, this research cannot exclude the possibility that alternative forms of Superbrain Yoga might be effective or that it might have an effect on cognitive skills not captured by the Number Facility Test.”

 

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