By Ellen Feldman, MD
Altru Health System, Grand Forks, ND
Dr. Feldman reports no financial relationships relevant to this field of study.
- This sweeping systematic review of English and Chinese literature regarding mind-body interventions and cognitive performance in older adults identified 19 fair-good quality studies for inclusion.
- Mind-body interventions include Tai chi, yoga, Pilates, and Qigong.
- Relative to control, mind-body interventions were associated with benefits in:
- Global cognition (Hedges g = 0.23: small effect size);
- Executive function (Hedges g = 0.25-0.65: moderate effect size);
- Learning and memory (Hedges g = 0.37-0.49: small-moderate effect size)
- Language (Hedges g = 0.35: small effect size).
SYNOPSIS: A meta-analysis regarding mind-body techniques and cognitive fitness in older adults points to enhanced cognitive performance associated with mind-body interventions in older persons — especially those without preexisting cognitive decline.
SOURCE: Zhang Y, et al. The effects of mind-body exercise on cognitive performance in elderly: A systematic review and meta-analysis. Int J Environ Res Public Health 2018;15:2791.
Medical advances are eradicating disease systematically, death rates are falling globally, and life expectation is on the rise. In the United States, by 2050, about 88 million persons are likely to be older than 65 years of age — more than double the 2010 record of 40.2 million.1 With these advances, public health focus must shift to a relatively new area involving the challenge of understanding, preventing, and treating diseases linked with aging (e.g., Alzheimer’s disease, hypertension, and arthritis). On the same page, understanding, preventing and addressing what appears to be normal deterioration associated with aging is equally important in caring for the aging population.
Cognitive aging may be defined as the decline in cognitive processing that occurs as people get older. Age-related impairments in reasoning, memory, and processing speed develop naturally with age, or so we think.2 Recognizing that mind-body exercises have shown some efficacy in treating a variety of disorders, such as chronic pain, joint problems, and some mood disorders,3,4 Zhang et al conducted a comprehensive review on studies investigating a relationship between (specific) mind-body exercises and cognitive performance. This comprehensive review covered both English and Chinese language literature. The authors searched for randomized trials of at least fair quality in this field involving persons older than 60 years with or without known cognitive disorders or deterioration. Additional criteria for inclusion in the meta-analysis were the use of one or more of the following mind-body interventions: Tai chi, Qigong, yoga, Pilates, and at least one standardized measure of cognitive outcome.
Using these inclusion criteria, Zhang et al identified 19 eligible studies: 15 studies included one control group and the remainder included two or more such groups. Sample sizes ranged from 28 to 456, with 2,539 participants in total across the groups. Other areas of diversity across the studies included type and duration of intervention, time devoted to the intervention, and type of intervention assigned to control group. For example, 15 of the studies involved Tai chi, four involved yoga, two involved Qigong, and one involved Pilates. Outcome measures involved aspects of cognitive functioning, but the specific outcome measured and tool used varied between the studies. Zhang et al simplified the measures by grouping them into five main categories: global cognition, executive functioning, learning and memory, visual spatial ability, and language.
Tables 1-5 display results for each of the five general categories reflecting a measure of cognitive fitness. Hedges’ g is a measure of effect size. In general, a Hedges’ g of 0.2-0.49 indicates a small difference between intervention and control, while 0.5-0.79 indicates a medium effect, and ≥ 0.8 indicates a large effect.5
Table 1: Mind-Body Exercise and Executive Functioning: Small to Moderate Effect
|
|
Number of studies
|
8
|
8
|
8
|
7
|
|
Outcome measurement tool
|
Trial Making test A
|
Trial making test B
|
Digit span
|
Stroop test
|
|
Pooled Hedges’ g
|
0.65, moderate effect
|
0.46, small to moderate effect
|
0.25, small effect
|
0.32, small effect
|
|
95% confidence interval
|
0.20–1.10
|
0.26–0.27
|
0.09–0.42
|
0.015–0.49
|
|
P value
|
< 0.001
|
< 0.001
|
0.003
|
< 0.001
|
Table 2: Mind-Body Exercise and Global Cognitive Functioning: Small Effect Size
|
|
Number of studies
|
10
|
|
Outcome measurement tool
|
Mini mental status exam (MMSE)
|
|
Pooled Hedges’ g
|
0.23 (small)
|
|
95% confidence interval
|
0.08-0.39
|
|
P value
|
0.003
|
Table 3: Mind-Body Exercise and Learning and Memory: Small to Moderate Effect
|
|
Number of studies
|
7
|
8
|
|
Outcome measurement tool
|
Immediate recall
|
Delayed recall
|
|
Pooled Hedges’ g
|
0.37
small effect
|
0.49
Small to moderate effect
|
|
95% confidence interval
|
0.20-0.54
|
0.29-0.69
|
|
P value
|
< 0.001
|
< 0.001
|
Table 4: Mind-Body Exercise and Visuospatial Ability: Small Effect
|
|
Number of studies
|
8
|
|
Outcome measurement tool
|
Clock–drawing;
Ray’s complex figure test
|
|
Pooled Hedges’ g
|
0.18
small effect
|
|
95% confidence interval
|
0.02–0.35
|
|
P value
|
0.03
|
Table 5: Mind-Body Exercise and Visuospatial Ability: Small Effect
|
|
Number of studies
|
8
|
|
Outcome measurement tool
|
Boston Naming Test
|
|
Pooled Hedges’ g
|
0.35, small effect
|
|
95% confidence interval
|
0.14 – 0.56
|
|
P value
|
0.001
|
In addition to organizing data according to outcome measures, the authors analyzed two subgroups. The first looked at respondents with known minimal brain impairment (MCI) vs. non- MCI, and the second looked at total training time. Cognitive improvement was associated with mind-body exercise in all categories of outcome measures with the exception of language. Results of the naming test showed a significantly larger effect for participants without MCI, as shown in Table 6. The P value of the difference was 0.02. Significant improvement in cognitive functioning was associated with increase in total training time per day in multiple spheres. Specific training times were not noted.
Table 6: Subgroup Results
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|
Subgroup
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Number
of studies
|
Hedges’ g
|
|
Minimal cognitive impairment (MCI)
|
4
|
0.14: no effect
|
|
Non-MCI
|
5
|
0.49: small to moderate effect
|
COMMENTARY
At first glance, this meta-analysis of 19 studies regarding mind-body exercise and cognitive fitness in adults 60 years of age and older appears straightforward. A deeper look reveals the complexity inherent in such a study. Zhang et al needed to account for several different mind-body techniques, widely different sample sizes, and a variety of outcome measures. The heterogeneity led the group to temper conclusions regarding the efficacy of mind-body exercise in improving cognitive measures in the elderly and to recommend further investigation. In addition, there was a large gap in that meditation was not included as a mind-body technique.
Keeping this in mind, several aspects of this work bear scrutiny and discussion and should generate excitement. Given the myriad of consequences associated with decline in cognitive functioning and the prospect of growth in the elderly population, any reasonable intervention with an indication for improving cognitive fitness with age is well worth pursuing.
Zhang et al did not attempt to compare the specified mind-body interventions head to head nor was there an attempt to compare or contrast the impact of these mind-body interventions with other forms of exercise. Age-related vulnerability to the effect of the exercises was not explored. A variety of mind-body interventions, including meditation, were not investigated. Studies regarding these points and other exercise-based interventions deserve ongoing and future investigation. In addition, follow-up and longer-term studies are necessary to determine the longevity of response.
By including Chinese studies with the meta-analysis, Zhang et al added important depth to the study and set a bar for further investigations and reviews. The availability of certified providers able to teach and train specific mind-body exercises will vary according to location. Thus, casting a broad net for inclusion helps to account for geographic limitations.
Financial barriers may prevent some in the elderly population from participating in mind-body exercises. If future robust studies continue to find significant benefit from such interventions, perhaps insurers will take notice and consider coverage.
It is interesting to think about mechanism of action. What do we know about the brain and exercise that can help explain how mind-body exercise may contribute to cognitive improvement? Perhaps one way to approach this question is to consider the elements that the mind-body exercises included in this study had in common. Among other factors, each incorporated breathing, attention, stretching of skeletal muscles (and relaxation of these muscles) and a connection between internal focus and body movement. We know these types of exercises are associated with increased hippocampal volume and possibly with frontal lobe stimulation — two brain regions involved in learning and memory and possible key areas for cognitive health.6,7
The finding that participants with a preexisting diagnosis of MCI had significantly less improvement in a measure of language than those without such a diagnosis is interesting. Further investigation may increase our understanding of an underlying mechanism of action. Equally intriguing and needing further scrutiny is the absence of difference in other areas of cognitive fitness.
Our patients come in all shapes, sizes, and carry with them a true diversity of limitations and strengths. Offering mind-body exercise may be an answer to those who feel intimidated by the prospect of more conventional types of physical activity. With medical evidence in hand, a provider is on safe ground recommending these techniques as part of a comprehensive wellness plan as patients’ age. Work remains in this field before definitive answers emerge. However, this study clearly provides evidence of the importance of exercise in maintaining and improving health, and specifically the role of mind-body exercise such as Tai chi, yoga, Qigong, and Pilates in addressing cognitive fitness.
REFERENCES
- IHME. Life expectancy increases globally as death toll falls from major diseases. Available at: https://bit.ly/1Ce9NUZ. Accessed June 19, 2019.
- Harada CN, et al. Normal cognitive aging. Clin Geriatr Med 2013;29:737-752.
- NIH Fact Sheets. Mind-body medicine practices in complementary and alternative medicine. Available at: https://bit.ly/2Kr4L5u. Accessed June 18, 2019.
- Science Direct. Mind-Body Interventions. Available at: https://bit.ly/2WRvN7N. Accessed June 19, 2019.
- Statistics How To. Hedges' g: Definition, Formula. Available at: https://bit.ly/2IqGMks. Accessed June 19, 2019.
- Gothe NP, et al. Differences in brain structure and function among yoga practitioners and controls. Front Integr Neurosci 2018;12:26.
- Wei GX, et al. Editorial: Brain-mind-body practice and health. Front Psychol 2017;8:1886.
