By David Kiefer, MD
Clinical Assistant Professor, Department of Family Medicine, University of Wisconsin; Clinical Assistant Professor of Medicine, Arizona Center for Integrative Medicine, University of Arizona, Tucson
Dr. Kiefer reports no financial relationships relevant to this field of study.
- Forty-three people attended a six-week yoga class. Five surveys explored working memory, and one 15-item questionnaire detailed mindfulness.
- Four of five memory tests showed a statistically significant, but possible clinically negligible, improvement; mindfulness scores also improved.
SYNOPSIS: The authors of this small pilot study showed that a six-week yoga class led to benefits in working memory and mindfulness.
SOURCE: Brunner D, et al. A yoga program for cognitive enhancement. PLoS One 2017;12(8):e0182366.
These days, it seems like in most communities there are a plethora of yoga studios catering to many demographics and helping people to connect their minds, bodies, and breath to promote relaxation and well-being, if not address specific health concerns. Lagging a bit is the application of this modality as a proven therapeutic tool in clinical practice. Most research has focused on the use of yoga for physical ailments, such as back pain, but Brunner et al stepped into a unique niche of looking at the cognitive effects of a yoga practice.
The authors hypothesized that the mindfulness component of yoga, including meditative techniques and body awareness, might benefit what they call “working memory.” As detailed by the authors, working memory is a short-term collection and processing of information that has both a maintenance component and a manipulation component. The characteristics of these two parts, and the survey instruments used for testing them, are described in Table 1. Specifically, the researchers used three aspects of the Wechsler Adult Intelligence Scale (WAIS), including the WAIS Digit Span Forward (listening to and then remembering numbers in the same order, score 0-14), WAIS Digit Span Backward (listening to and remembering numbers in a reverse order, score 0-14), and WAIS Digit Span Sequencing (listening to and remembering numbers in an ascending order), which is less supported by results in the medical literature. In addition, they used the WAIS Letter-number Sequencing (listening to and remembering numbers and letters in numerical and alphabetical order, respectively), and 15-item (each with a six-item Likert scale) self-report mindfulness scale to assess self-awareness and well-being.
Table 1: Maintenance and Manipulation Aspects of Working Memory
|
| |
Maintenance Sub-Domain
of Working Memory
|
Manipulation Sub-Domain of Working Memory
|
|
General characteristics
|
Temporary information storage
|
Temporary storage, as well as using the information associated with various tasks
|
|
Surveys used to assess
|
Wechsler Adult Intelligence Scale (WAIS) Digit Span Forward
|
WAIS Digit Span Backward; WAIS Letter-Number Sequencing; WAIS Digit Span Sequencing (used but not well corroborated in the literature yet)
|
The researchers recruited adults through Texas State University who did not have any physical condition that would prohibit their involvement in a yoga class. A total of 43 people enrolled in the study. The mean age was 25 years, and half had no prior yoga experience. The participants completed all of the surveys and answered basic demographic questions prior to the start of the yoga classes. They were then given the option of six weekly one-hour yoga classes (n = 41) or six twice weekly one-hour yoga classes (n = 2). The researchers chose to use a hatha-type yoga, which included poses (asanas), breathing (pranayama), and a 10-minute guided meditation while supine.
Over the course of the study period, some improvements in the primary outcomes were seen. (See Table 2.) There was a statistically significant improvement in four of five variables, although in all cases the absolute improvement in survey score was minimal, of marginal clinical significance. Interestingly, the mindfulness scores improved, but was not correlated with changes in cognition as determined by statistical analyses (see below for relevance).
Table 2: Change in Scores for the Primary Outcomes Pre- and Post-Yoga Class
|
| |
Baseline
(pre-yoga class)
|
Post-yoga class
|
P value
(difference from baseline)
|
|
WAIS Digit Span Forward
|
9.2
|
10.0
|
P < 0.01
|
|
WAIS Digit Span Backward
|
8.0
|
9.0
|
P < 0.001
|
|
WAIS Letter-Number Sequencing
|
8.4
|
9.6
|
P < 0.001
|
|
WAIS Digit Span Sequencing
|
9.1
|
9.6
|
not significant
|
|
Self-report mindfulness scale
|
3.6
|
4.1
|
P < 0.001
|
Study participants who had done yoga in the past showed greater improvements in scores during the study period (P = 0.008). This overall difference was found to be due to the WAIS Letter Number Sequencing test, considered to be a cognitively more difficult test; in fact, the statistics revealed that the Letter Number Sequencing test change was only found in those who had done yoga before. There was no limitation on yoga activities outside the official classes, and 25 participants chose to do so. This could have affected the post-class survey scores, but statistical analyses (using the Pearson’s correlation test) showed that there was no connection between the time spent doing home yoga with the results in any of the five surveys.
COMMENTARY
Clearly, this is a pilot study. The numbers are low, and there was no control group. That said, a lot of data about memory were collected. It appears that yoga may improve working memory from both cognitive and non-cognitive effects, and the former may not be mediated through mindful awareness. The researchers argued that this illustrates that yoga is operating on several levels and by several mechanisms to achieve improvements in working memory. Are the results clinically significant? Difficult to say, but the researchers did not detail the percentage improvements nor the denominator for absolute changes. Some basic math shows that the approximate 1-point improvement in mindfulness scores on a 15-item survey, each with a six-point Likert scale (90 total points possible), means about a 1% improvement. Is a yoga class worth that amount of improvement in mindfulness and/or an undetermined amount of improvement in working memory? It probably depends on the person, but given the lack of a downside to yoga, and a dearth of other proven therapies to improve working memory, many people would say “yes!”
As we wait for other studies to detail the health effects of yoga, some groups are forging ahead with yoga programs. Large health systems are recognizing the therapeutic value of yoga as a healing modality. For example, the Veterans Health Administration (VHA) system of hospitals and clinics include yoga as one of the complementary and integrative health approaches to be included in expansion throughout the VHA system.1 Their official description of yoga, called therapeutic yoga, mentions the various health conditions that might benefit from yoga.2
There are many types of yoga, and these researchers chose a hatha-type class. It is difficult to say whether other yoga approaches would also lead to the benefits seen in this study. Clearly, this is an area for future exploration. In addition, participants mostly were young people generally in good health. The authors did not comment on the application of yoga to people with medical diagnoses including more severe memory impairment. Perhaps the greatest contribution of this work is that a common mind-body activity, such as yoga, has benefits on several different aspects or mechanisms associated with memory. Memory is a complex phenomenon associated with numerous mechanisms. In the middle of the tough yoga pose, now we can know that some or all of those neuronal pathways are perhaps being nudged toward better functioning.
REFERENCES
- Kligler B. Integrative Health in The Veterans Health Administration. Med Acupuncture 2017;29:187-188.
- U.S. Department of Veterans Affairs. Whole Health for Life. An Introduction to Yoga for Whole Health. Available at: www.va.gov/PATIENTCENTEREDCARE/Veteran-Handouts/An_Introduction_to_Yoga_for_Whole_Health.asp. Accessed: June 3, 2019.
