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e782
The Gerontologist
cite as: Gerontologist, 2019, Vol. 59, No. 6, e782–e790
doi:10.1093/geront/gnz022
Advance Access publication February 23, 2019
© The Author(s) 2019. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved.
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Review Article
Effects of Meditation and Mind–Body Exercises on Older
Adults’ Cognitive Performance: AMeta-analysis
JohnS.Y. Chan, PhD Kanfeng Deng, MSc, Jiamin Wu, MSc, and JinH. Yan, PhD*
Laboratory of Neuromotor Control and Learning, Shenzhen University, China.
*Address correspondence to: Jin H.Yan, PhD, Laboratory of Neuromotor Control and Learning, Shenzhen University, 3688 Nan Hai Ave, Shenzhen,
Guangdong 518060, P.R. China. E-mail: jhyan@sfsu.edu
Received: October 24, 2018; Editorial Decision Date: January 15, 2019
Decision Editor: Patricia C.Heyn, PhD
Abstract
Background and Objectives: Meditation and mind–body exercises are suggested to delay decline or enhance cognitive
capabilities in older adults. However, their effectiveness remains uncertain. This study assessed the effectiveness of
meditation and mind–body exercises to improve cognition in elderly people aged 60years or above. Moderator variables
were also explored.
Research Design and Methods: A databases search (MEDLINE, EMBASE, CINAHL, PsycINFO, Cochrane Library, Web of
Science, CNKI, and Wangfang) was conducted from the rst available date to January 10, 2018. Inclusion criteria include
(a) human older adults aged 60years or above, (b) meditation, Tai Chi, Qigong, or yoga intervention, (c) intervention
should be structured, (d) inclusion of a control group, (e) at least one outcome measure of cognition was measured at
baseline and post-training, and (f) peer-reviewed journal articles in English or Chinese.
Results: Forty-one studies (N=3,551) were included in the meta-analysis. In general, meditation and mind–body exercises
improve cognition in the elderly people (SMD=0.34, 95% CI: 0.19 to 0.48), but the cognition-enhancing effects depend
on the type of exercise. In addition, cognitive performance is only improved when the length of intervention is longer than
12 weeks, exercise frequency is 3–7 times/week, or duration of an exercise session is 45–60min/session.
Discussion and Implications: This study suggests that meditation and mind–body exercises are effective to improve
cognition of older adults aged 60years or above, and exercise parameters should be considered for intervention planning.
Keywords: Alternative and complementary medicine/care/therapy, Cognition, Dementia, Exercise/physical activity
The world population is aging. The proportion of older
adults aged 60years or above is expected to increase from
12% to 22% between the years 2015 and 2050 (World
Health Organization, 2018). Normal aging is associated not
only with reduced physical health but also with cognitive
decline. Other than healthy aging, some older people may
have some forms of dementia. It is estimated that 47 million
people worldwide are having dementia, and 66 million
people could be affected by the year 2030 (Prince et al.,
2013). Given a large number of affected people and the
great burden imposed on the health care system, a search
for effective interventions to ameliorate cognitive decline
or improve cognitive functions in the older population is of
immense signicance.
Older adults of different cognitive statuses can improve
cognitive functions through exercise participation (Angevaren,
Aufdemkampe, Verhaar, Aleman, & Vanhees, 2008; Groot
etal., 2016). Although cognition is usually reduced in older
adults, abundant research has demonstrated the malleability of
elderly people’s neural system, which enables them to acquire
new skills or restore the affected capabilities (Cai, Chan,
Yan, & Peng, 2014; Wu, Chan, & Yan, 2016). Behavioral
and psychological interventions (including physical exercises
and cognitively stimulating activities) are recommended for
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improving cognitive functions of older adults. The association
between physical activity and reduced risks of cognitive
disorders in older adults has been documented (Buchman,
Boyle, Yu, Shah, Wilson, & Bennett, 2012). The benets of
physical activity on cognition are believed to be mediated
by the promotion of neurogenesis, synaptogenesis, and
capillarization (Colcombe & Kramer, 2003), and increases
in brain-derived neurotrophic factor and insulin-like growth
factors (Cotman, Berchtold, & Christie, 2007; Vaynman,
Ying, & Gomez-Pinilla, 2004). These interacting factors
are supposed to contribute to the neuroprotective effects of
exercises on elderly people’s cognition.
Besides traditional physical exercises, there is a growing
number of research into the benets of mind–body exercises
over the past decades. They are usually performed at a slow pace
and low intensity, and thus, are particularly suitable for older
adults (Guo, Shi, Yu, & Qiu, 2016; Taylor-Piliae etal., 2010).
Compared to physical exercises, mind–body exercises have a
higher cognitive demand and emphasize cognitive well-being.
It has been suggested that exercise interventions with a higher
cognitive demand are particularly efcacious to slow down
age-related cognitive decline (Raichlen & Alexander, 2017).
A recent meta-analysis has also shown that a combination
of physical and cognitive activities is ideal for treating or
preventing cognitive decline in older adults (Gheysen et al.,
2018). Tai Chi, Qigong, and yoga are prime examples of
mind–body exercises. Tai Chi is a multicomponent exercise
that trains exercisers’ aerobic, anaerobic, and exibility
capacities. Qigong involves a set of static or dynamic exercises
through coordinated breathing and physical movements to
cultivate one’s internal energy to achieve body healing, and
Baduanjin is one of the most common forms of Qigong (Chen
etal., 2013). Yoga originates from ancient India and includes
practice of postures, breathing, and meditation to support
optimal homeostasis. There is increasing evidence to show
the efcacy of mind–body exercises to improve the cognitive
functions of the elderly people (Gothe & McAuley, 2015; Wu,
Wang, Burgess, & Wu, 2013).
Mind–body exercises usually include meditation as a
part of training. Meditation involves various emotional and
attentional regulatory strategies to achieve cognitive well-
being and emotional balance (Lutz, Dunne, & Davidson,
2006). There is a growing body of literature to suggest that
meditation may benet the cognitive functions in older
adults and those with neurodegenerative diseases (Newberg
etal., 2014), possibly through enhancements of brain regions
related to interoception and attention (Hölzel etal., 2008).
In this study, we investigated if meditation and mind–
body exercises (meditation, Qigong, Tai Chi, yoga) benet
older adults’ cognition via the meta-analytic approach.
Further examinations will be conducted to compare their
effectiveness. To improve prescription of meditation and
mind–body exercises in the future, we also analyzed the
exercise moderators associated with cognitive benets in
older adults. It was hypothesized that, relative to the control
participants, older adults in meditation and mind–body
exercises show cognitive improvement. As suggested in
previous research, different types of exercise may have varying
inuences on different cognitive domains (Voss, Nagamatsu,
Liu-Ambrose, & Kramer, 2011). We hypothesized that
cognitive improvement depends on the type of exercise.
Methods
The systematic review with meta-analysis was conducted
in accordance with the Preferred Reporting Items for
Systematic Reviews and Meta-Analyses (PRISMA) (Moher,
Liberati, Tetzlaff, & Altman, 2009).
Search Strategy
A computer search of MEDLINE, EMBASE, CINAHL,
PsycINFO, Cochrane Library, and Web of Science was
conducted up to January 10, 2018, using the search phrase,
(Tai Chi OR Tai Ji OR yoga OR Baduanjin OR Qigong OR
meditation) AND (cognition OR attention OR memory OR
executive function). The Chinese equivalent search phrase
was used in the CNKI and Wangfang databases to search
for Chinese articles.
All returned titles were screened by the rst author (J.
S. Y. Chan) to exclude duplicate and irrelevant studies
based on the article title. The abstract of each remaining
study was then independently reviewed by two investigators
(J. Wu and YD), this stage was overinclusive. In case of
disagreement of judgment, the article would be carried to
the next screening stage. Subsequently, the full texts of the
remaining studies were independently reviewed against
the inclusion criteria. The interrater agreement was high
(Cohen’s kappa= 0.78). In this stage, the reviewers had
to discuss with each other to reach a consensus in case of
disagreements. Reviewers also looked at the bibliography
of the included articles and published review articles to
avoid missing potentially relevant studies.
Inclusion and Exclusion Criteria
Studies were included if they met the following criteria:
(a) studies of human older adults (60 years or older);
(b) participants can be cognitively impaired (e.g., mild
cognitive impairment [MCI] or dementia), but should not
have other neurological (e.g., stroke) and/or mental illnesses
(e.g., depression); (c) a structured exercise program of any
duration, frequency, or intensity; (d) a control group was
included; (e) at least one outcome measure of cognition
was measured at baseline and post-training; and (f) peer-
reviewed articles in English or Chinese.
Data Extraction
Data of the study population, intervention, and outcome
measures were independently extracted with a standardized
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form by two investigators (K. Deng and CW). For both
intervention and control groups, sample size, mean values
of outcome measure at baseline and post-intervention,
and baseline standard errors were recorded. In addition
to outcomes measures, potential moderators were also
recorded. Type of exercise was categorically coded as
meditation, Qigong, Tai Chi, or yoga. Previous studies have
found impairments in attention (Chao & Knight, 1997),
processing speed (Finkel, Reynolds, McArdle, & Pedersen,
2007), verbal uency (Kempler, Teng, Dick, Taussig,
& Davis, 1998), and memory and executive functions
(Buckner, 2004) in elderly people. Thus, we focused on these
cognitive domains in this study. The cognitive domain was
coded as attention, processing speed, verbal uency, short-
term memory, working memory, executive function, or
global cognition. On the basis of the report in the included
studies, participants’ cognitive status was coded as healthy,
MCI, dementia, or unclear. Three exercise parameters
were recorded (program length, exercise frequency, and
duration). The program length (short: ≤12 weeks; medium:
13–26 weeks; long: >26 weeks), exercise frequency (per
week: low: ≤2; medium: 3–4; high: 5–7), and exercise
duration (per session: short: ≤45 min; medium: >45 to
≤60min; long: >60min) were coded using a prior meta-
analytic review as a guide (Northey, Cherbuin, Pumpa,
Smee, & Rattray, 2018). The mean age of participants, year
of education, and female percentage in a study were also
extracted as continuous moderators.
Risk of Bias Assessment
Two researchers independently assessed the risk of bias
of the included studies with the Cochrane Collaboration
Guidelines across the following domains: randomization;
allocation concealment; blinding (outcome assessor),
incomplete data, selective reporting, and any other risk of
bias. The Physiotherapy Evidence Database (PEDro) scale
was also used to evaluate the risk of bias of the included
studies (www.pedro.org.au). The scale contains 11 items
(yes/no questions), covering the domains of randomization,
concealed allocation, blinding and quality of reporting.
PEDro score for each study was obtained by counting the
number of yes (except for item 1), the score can range from
0 to 10. Aprevious study has suggested that a PEDro score
more than 6 indicates good quality of study (Gonzalez etal.,
2018). In this study, we considered studies with a PEDro
score more than 6 as having a low risk of bias. Interrater
agreement was high using either the Cochrane Collaboration
Guidelines (Cohen’s kappa=0.7) or the PEDro scale (Cohen’s
kappa= 0.72). Discrepancies in the risk of bias assessment
were resolved by discussion between the reviewers.
Statistical Analyses
Cognitive measures were the primary outcomes. To
account for the dependency of outcome measures within
studies, a multilevel random-effects meta-analysis
was conducted in R (version 3.5.0) with the metafor
package (version 2.0-0) using an unrestricted maximum
likelihood estimator (Viechtbauer, 2010). On the basis
of the approach of Becker (1988), standardized mean
difference (SMD) was computed as the effect size using
formulae 1–3, where gT and gC are the standardized
mean change for the intervention and control groups,
respectively.
−
X
pre
-
intervention,
−
X
post
-
intervention,
SD
pre
-intervention
,
and n indicate the pre-intervention and post-intervention
means, pre-intervention SD, and sample size, respectively.
c
(
n−1
)=
2
/(
n−1
) Γ [(
n−1
)/
2
]/Γ[ (
n−2
)/
2]
is a bias-correction factor. The formulae assume that
the pre-intervention and post-intervention variances
are homogeneous. A positive SMD indicates a greater
cognitive benet in the experimental group, relative to the
controlgroup.
g
T=c(nT−1)
Ã
−
Xpost-intervention,T−
−
Xpre-intervention,T
SDpre-intervention,T
(1)
gC=c(nC−1)
Ã
−
Xpost-intervention,C−
−
Xpre-intervention,C
SDpre-intervention,C
(2)
SMD =gT−gC
(3)
Cochran’s Q test was used to assess heterogeneity. In
addition, I2 (proportion of variance due to heterogeneity)
was also computed to quantify the extent of heterogeneity
(Higgins & Thompson, 2002). Separate models were tted
to determine the main effects of different moderators.
To gain better insights into this issue, we also examined
the interaction of type of exercise and cognitive domain.
Statistical signicance was determined by omnibus
tests. Exploratory analyses of the moderating effects of
mean age of participants, year of education, and female
percentage were conducted by meta-regression. To evaluate
the inuence of risk of bias on the meta-analytic results,
separate random-effects models were tted for studies of
low risk of bias (PEDro score >6) and studies of high risk
of bias (PEDro score ≤6).
Publication bias was assessed with Egger’s regression. In
Egger’s regression, a signicant deviation of the y-intercept
from zero might indicate the presence of publication bias.
In addition, a Rosenthal fail-safe N test was also conducted
to estimate the number of unpublished null studies required
to nullify the overall effects at the 95% level.
Results
The PRISMA owchart was presented in Figure 1. In the
initial search, 5,113 records were returned of which 427
studies were retrieved for full-text reading. Eventually,
41 studies met all the inclusion criteria for quantitative
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analyses, involving 3,551 participants. The included studies
can be grouped by the type of exercise into meditation
(k=11), Qigong (k=9), Tai Chi (k=14), and yoga (k=9).
Characteristics of the included studies are summarized in
Supplementary Table 1 and a forest plot of the included
studies was presented in Supplementary Figure 1. As was
observed in Supplementary Table 1 and Supplementary
Figure 1, studies of a large sample size usually have a
narrower condence interval(CI).
Risk ofBias
Risk of bias of the included studies is shown in Figure 2.
Most of the studies have low risks in sequence generation,
incomplete outcome data, selective reporting, and other
bias. However, in terms of allocation concealment and
blinding, the risks are unclear in most of the included
studies. Risk of bias of each included study is summarized
in Supplementary Tables 2 and 3. On the basis of the PEDro
scale score, 78% of the included studies can be classied as
having a low risk ofbias.
Effects of Meditation and Mind–Body Exercises
on Cognition
Results of this meta-analysis show that meditation and
mind–body exercises, relative to controls, improve cognition
in the elderly people (SMD=0.34, 95% CI: 0.19 to 0.48,
p < .001), and there is signicant heterogeneity across
studies (Q(152)= 604.30, p < .001). Additional analyses
showed that the pooled effect size was lower for studies of
low risk of bias (SMD=0.27, 95% CI: 0.12 to 0.43) than
for studies of high risk of bias (SMD=0.59, 95% CI: 0.26
to 0.93) (Supplementary Figure 2). This suggests that an
inclusion of studies of high risk of bias may inate the pooled
effect size but not change the conclusion (i.e., meditation
and mind–body exercises have small-to-moderate effects to
improve cognition in the elderly people).
The funnel plot appears asymmetrical (Figure 3),
however, Egger’s regression indicates an absence of funnel
plot asymmetry (p=.26). According to previous simulation
results (Fragkos, Tsagris, & Frangos, 2014), for a meta-
analysis of 41 studies, the threshold of fail-safe N is 369.
The estimated fail-safe N (12,699) is far above the threshold.
On the basis of the Egger’s regression and fail-safe N, the
meta-analytic results should be robust to publication bias. I2
indicates that heterogeneity is high across studies (80.5%).
Moderator Analysis
To investigate the potential sources of heterogeneity,
moderators were analyzed in separate models. Results of
Figure 1. Study selection flowchart.
Figure 2. Risk of bias of the included studies.
Figure 3. Funnel plot for visual inspection of publication bias.
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moderator analyses are presented in Table 1. Although
separate analyses were conducted for different moderators,
heterogeneity remains high (I2 > 70%). This may implicate
that the high heterogeneity observed is attributed to an
interaction of multiple moderators or related to factors not
considered in the moderator analyses.
Exercise moderators
Concerning the type of exercise, only meditation (p < .001)
and Qigong (p= .001) produce signicant positive effects
on cognition. Studies, where the program length is medium
to high, have shown signicant cognitive improvement
(p < .001). Only medium-to-high exercise frequency is
related to cognitive improvement (p < .02). In terms of
exercise duration, only medium duration is associated with
positive effects on cognition (p < .001), whereas short and
long durations produce nonsignicant effects on cognition
(p > .34).
Cognitive moderators
The effect of meditation and mind–body exercises on
cognition is signicant for all cognitive domains (p < .01),
except processing speed (p=.06). The cognition-enhancing
effects are only observed in studies of participants with
MCI (p < .001) or unclear cognitive status (p = .006).
Furthermore, there is a signicant interaction between
type of exercise and cognitive domain (p < .001) (Table 2),
suggesting that the effectiveness of different types of
Table 1. Results of Moderator Analyses
Moderator
No. of
effect sizes
Estimated mean SMD
(95% CI) p value Q statistic I2
Omnibus test of
moderators
Type of exercise Q(149)=447.3,
p < .001
72.4% Q(4)=32.8, p < .001
Meditation 45 0.41 (0.16 to 0.65) .001
Qigong 21 0.72 (0.41 to 1.03) <.001
Tai Chi 48 0.19 (−0.03 to 0.41) .09
Yoga 39 0.15 (−0.13 to 0.44) .3
Cognitive domain Q(146)=577.5,
p < .001
79.6% Q(7)=26.5, p < .001
Attention 6 0.33 (0.01 to 0.65) .04
Executive function 32 0.39 (0.21 to 0.56) <.001
Global cognition 23 0.42 (0.24 to 0.61) <0001
Processing speed 6 0.36 (−0.02 to 0.74) .06
Short-term memory 32 0.28 (0.10 to 0.46) .002
Verbal uency 17 0.27 (0.06 to 0.48) .01
Working memory 37 0.27 (0.10 to 0.44) .002
Cognitive status Q(149)=592.5,
p < .001
79.9% Q(4)=25.8, p < .001
Healthy 21 0.17 (−0.20 to 0.53) .4
MCI 53 0.53 (0.28 to 0.78) <.001
Dementia 4 −0.14 (−1.08 to 0.79) .8
Unclear 75 0.29 (0.08 to 0.49) .006
Program length Q(150)=555.7,
p < .001
79% Q(3)=25.4, p < .001
Short (≤12 weeks) 42 0.14 (−0.15 to 0.44) .4
Medium (13–26 weeks) 82 0.36 (0.17 to 0.55) <.001
Long (>26 weeks) 29 0.72 (0.38 to 1.05) <.001
Exercise frequency Q(146)=540.4,
p < .001
78.8% Q(3)=23.7, p < .001
Low (≤2) 37 0.22 (−0.04 to 0.48) .1
Medium (3–4) 60 0.29 (0.04 to 0.55) .02
High (5–7) 52 0.50 (0.25 to 0.74) <.001
Exercise duration Q(131)=425.0,
p < .001
Q(3)=29.2, p < .001
Short (≤45min) 54 0.03 (−0.20 to 0.27) .8
Medium (>45 to ≤60min) 67 0.51 (0.32 to 0.70) <.001
Long (>60min) 13 0.21 (−0.22 to 0.65) .3
Note: CI=condence interval; MCI=mild cognitive impairment; SMD=standardized mean difference.
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exercise may vary in different cognitive domains. It is shown
that meditation improves attention, global cognition, and
working memory (moderate-to-large effects). Qigong
improves global cognition, short-term memory, and
working memory (moderate-to-large effects). Tai Chi
improves executive function and global cognition (small
effects). Yoga improves executive function (small effect)
and processing speed (large effect). There is no signicant
difference of change in executive function following Tai
Chi and Yoga interventions (p = .89). In addition, the
change in global cognition following meditation does not
differ from those following Qigong (p = .54) or Tai Chi
(p= .14). However, the improvement in global cognition
after Qigong intervention is greater than that after Tai Chi
intervention (p = .04). The changes in working memory
following meditation and Qigong interventions do not
differ signicantly (p=.95).
Participant moderators
Supplementary Table 4 shows the meta-regression results.
There are nonsignicant effects of mean age of participants
(β=−0.01, 95% CI: −0.04 to 0.01, p = .20) and year of
education (β = −0.02, 95% CI: −0.05 to 0.01, p= .21)
on the estimated effect size. However, the percentage of
female participants in a study is negatively associated
with the estimated effect size (β=−0.01, 95% CI: −0.02
to 0, p = .01), suggesting that a 1% increase in female
participants is associated with a reduction of estimated
effect size by 0.01. It is important to note that, when year
of education is included as a moderator, heterogeneity
becomes small (I2=33.9%), suggesting that difference of
participants’ education level is the main contributor to the
heterogeneity across studies.
Discussion
Effectiveness of Meditation and Mind–Body
Exercises on Older Adults’ Cognition
We examined the effectiveness of meditation and different
mind–body exercises on elderly peoples’ cognitive functions
through meta-analytic methods. In general, meditation
and mind–body exercises enhance older adults’ cognitive
performance, except processing speed. Meditation and
mind–body exercises are particularly benecial for elderly
people with MCI. However, this does not mean that
meditation and mind–body exercises do not affect cognitive
performance of participants of other cognitive statuses, as
most of the included studies did not explicitly mention the
cognitive status of participants. Because of this, it would be
inappropriate to conclude that meditation and mind–body
exercises favor older adults of a certain cognitive status
over the others at thisstage.
Although meditation and mind–body exercises can
improve older adults’ cognition in general, follow-up
moderator analyses indicate that only meditation and
Qigong benet cognitive performance. This means that
meditation and Qigong should be considered if our aim is
to boost the general cognitive performance in the elderly
people. Further analyses show an interaction between
type of exercise and cognitive domain, suggesting that the
cognition-enhancing effects depend on the type of exercise.
Specically, meditation can improve attention, global
cognition, and working memory. Qigong improves global
cognition, short-term memory, and working memory. Tai
Chi improves executive function and global cognition.
Yoga improves executive function and processing speed. It
has been previously shown that meditation and mind–body
exercises can have different impacts on brain structures
Table 2. The Effects of Different Types of Mind–Body
Exercise on Cognition
No. of
effect sizes
Estimated mean
SMD (95% CI) p value
Attention
Meditation 2 1.01 (0.20 to 1.81) .01
Qigong 1 0.53 (−0.12 to 1.19) .11
Tai Chi 0 NA NA
Yoga 3 0.20 (−0.23 to 0.62) .4
Executive function
Meditation 12 0.29 (−0.02 to 0.61) .07
Qigong 1 0.86 (−0.11 to 1.82) .08
Tai Chi 9 0.30 (0.04 to 0.56) .03
Yoga 10 0.33 (0.03 to 0.63) .03
Global cognition
Mediation 5 0.56 (0.21 to 0.92) .002
Qigong 9 0.72 (0.39 to 1.05) <.0001
Tai Chi 9 0.28 (0.02 to 0.53) .03
Yoga 0 NA NA
Processing speed
Meditation 5 −0.05 (−0.52 to 0.42) .8
Qigong 0 NA NA
Tai Chi 0 NA NA
Yoga 1 0.99 (0.36 to 1.63) .002
Short-term memory
Meditation 7 0.24 (−0.10 to 0.58) .2
Qigong 6 0.86 (0.48 to 1.24) <.0001
Tai Chi 7 0.25 (−0.04 to 0.53) .09
Yoga 12 −0.01 (−0.31 to 0.29) .9
Verbal uency
Meditation 9 0.24 (−0.10 to 0.57) .2
Qigong 0 NA NA
Tai Chi 6 0.15 (−0.13 to 0.44) .3
Yoga 2 0.24 (−0.22 to 0.70) .3
Working memory
Meditation 5 0.55 (0.18 to 0.93) .004
Qigong 4 0.54 (0.12 to 0.95) .01
Tai Chi 17 0.19 (−0.05 to 0.43) .1
Yoga 11 0.07 (−0.23 to 0.37) .6
Note: NA=not available; SMD=standardized mean difference.
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and functions (Fox etal., 2014; Gothe, Hayes, Temali, &
Damoiseaux, 2018; Tao etal., 2017), and this may result
in the differential benets observed. Thus, if an older
adult wants to improve a specic cognitive ability, he or
she should take part in the corresponding exercise. For
instance, meditation, rather than other mind/mind–body
exercises, should be chosen for improving attention.
Besides directly affecting brain structures and functions,
mind–body exercises may inuence cognition through
changing one’s tness level. Tai Chi and yoga usually
have a higher level of physical activity than meditation
and Qigong. As suggested in previous reports, improved
aerobic tness can be associated with enhanced executive
functions and reduced age-related neurodegeneration
(Colcombe & Kramer, 2003), and this is consistent to
the present results that only Tai Chi and yoga improve
executive functions.
Exercise Prescription
Analyses of the moderating effects of exercise parameters
may help prescribe meditation and mind–body exercises
optimally. It is shown that cognitive performance is only
improved when the length of exercise program is medium
to long (>12 weeks), exercise frequency is medium to high
(3–7 times/week), or duration of an exercise session is
medium (>45 to ≤60min/session).
The present results are similar to those in a previous
meta-analysis on the effectiveness of physical exercise on
elderly cognition. In that study, a medium exercise duration
is associated with cognitive benets in older adults
(Northey etal., 2018). That study also reveals that cognitive
benets are independent of intervention length and exercise
frequency; however, we found cognitive benets only when
the exercise frequency and intervention length are at least
medium. Apossible reason of such discrepancies may be
due to the fact that physical exercises are more physically
demanding and can improve one’s physical tness more
readily, thus, inducing more prominent changes in the brain
in the physical exercisers (Colcombe & Kramer, 2003).
Limitations and Future Research
Several limitations have been noted, which can be
improved in future studies. Heterogeneity is signicant
even after moderator analyses. Because of the nature of
meditation and mind–body exercises, it is conceivable
that variations within each type of exercise contribute a
signicant amount of heterogeneity. Currently, there is a
limited number of studies into different subtypes of mind/
mind–body exercise; hence, it would be difcult to discern
and compare their effectiveness. In addition, based on I2
results, we found that participants’ education level may
be the main source of heterogeneity across studies. Thus,
future researchers should consider reporting sample’s
educationlevel.
In addition, the quality of the included studies is usually
moderate, and the methods of allocation concealment
and blinding are usually unclear (Figure 2). Allocation
concealment is to ensure that the assignment of participants
is not foreseeable by investigators and/or participants. In
case of a breach of allocation concealment, investigators
may recruit participants they prefer, and participants
may decide to participate in the study or not based on
the allocation results (self-selection bias). Blinding of
outcome assessor is to ensure that the outcome assessor
is not aware of the group assignment of a participant,
such that he or she can objectively record the outcome
measures. The risk of bias assessment has shown that
allocation concealment and blinding of outcome assessors
are seldom reported in studies on meditation and mind–
body exercises. Selection and detection biases may affect
the accuracy and generalizability of results. Therefore, it is
important for researchers to avoid these biases and report
their procedures of allocation concealment and blinding in
greater detail in the future.
Furthermore, most of the included studies did not
report participants’ cognitive status. Conceivably, cognitive
status has signicant impacts on one’s baseline cognitive
performance and room for improvement, thus, the
cognitive status of participants should be assessed and
clearly stated. In order to have a more comprehensive
understanding of the effectiveness of meditation and body–
mind exercises, future research may compare the change of
performance in participants of different cognitive statuses
after interventions.
The scope of this study is limited to “traditional”
mediation and mind–body exercises. In recent years,
mindfulness interventions (e.g., mindfulness-based stress
reduction) have been proposed to improve emotional
disturbances (Baer, 2003). As mindfulness interventions
and other mind/mind–body exercises are similar, we would
expect mindfulness interventions to be an option for
improving older people’s cognition; however, research on
this topic is scarce and more effort should be invested in
this area of study in the future.
Conclusions
This study used a multilevel design to account for the
dependency of effect sizes within studies and examined
the effects of mind/mind–body exercises on cognitive
improvement in the elderly people. In addition, the effects
of exercise length, duration, and frequency on cognitive
improvement were also explored. This knowledge informs
us how to optimally prescribe these activities to the elderly
people for maximal benets. In summary, meditation and
mind–body exercises improve cognition of older adults
aged 60 years or above, and the cognition-enhancing
effects depend on the type of exercise. To obtain optimal
effectiveness, intervention length and exercise frequency
should be at least medium, and the duration of an exercise
The Gerontologist, 2019, Vol. 59, No. 6
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session should be medium. Meditation and mind–body
exercises offer an accessible and effective means to improve
cognition in the elderly people, and possibly counteract
against the age-related cognitive decline. Given that
meditation and mind–body exercises have a low physical
demand, they are particularly suitable for older adults who
have reduced physical ability and/or medical conditions not
permitting them from practicing high-intensity exercises.
As there is high heterogeneity across the included studies,
more high-quality studies should be included in the future
to ascertain the efcacy of meditation and mind–body
exercises.
Supplementary Material
Supplementary data are available at The Gerontologist
online.
Funding
This work was supported by the Natural Science Foundation of
Shenzhen University and the Knowledge Innovation Program of
Shenzhen (grant number JCYJ20170302143406192).
Acknowledgment
We thank Chuqian Wei and Yingyi Deng for their assistance in
literature search and screening.
Conflict of Interest
We have no conict of interest to declare.
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