Physical performance is associated with working memory in older people with mild to severe cognitive impairment

Associations between physical activity, sedentary behaviour and cognitive domain performance of people living with mild cognitive impairment in the community

INTRODUCTION

Physical activity is known to positively influence cognitive performance. For adults with mild cognitive impairment (MCI), the relationship between physical activity levels and cognitive performance is unknown. This cross-sectional study aimed to determine if cognitive performance [as measured by the Montreal Cognitive Assessment (MoCA)] of people living in the community with MCI is associated with their physical activity levels or sedentary behaviour.

METHODS

ActivPAL™ accelerometers were used to objectively measure physical activity and sedentary behaviour for seven full days. Cognitive performance was measured using the MoCA.

CONSUMER AND COMMUNITY INVOLVEMENT

No involvement other than as research participants RESULTS: Eighty-two participants from the Balance on the Brain randomised controlled trial were included. Most participants were retired (88%), with 33 (40%) reporting a fall in the last year. The median MoCA score was 24 (IQR 22-26). Participants achieved a mean of 6296 (±2420) steps per day and were sedentary for 10.6 (±2) hours per day. The only physical activity outcomes that had a fair, positive correlation were moderate- to vigorous-intensity physical activity measures of total stepping time and total number of steps (with a cadence of ≥100 steps/min) with the orientation MoCA domain score (r(82) = 0.36, p ≤ 0.001 and r(82) = 0.37, p ≤ 0.001, respectively). Higher total sedentary time had a weak, positive correlation with better visuospatial/executive performance (r(82) = 0.23, p = 0.041). The orientation outcomes remained significant when analysed in an adjusted logistic regression model.

CONCLUSION

This study found that performance in the MoCA orientation domain had a fair-positive correlation with moderate-intensity physical activity (i.e., stepping time and step count with a cadence of ≥100 steps/min) as measured by a thigh-worn accelerometer for community-dwelling older adults with MCI. When considering the relationship between cognitive domains and sedentary behaviour, consideration may be needed regarding whether cognitive enhancing activities (such as crosswords and other brain games) are being performed, which may confound this relationship. Further investigation is required to confirm these results.

Effects of long-term Wuqinxi exercise on working memory in older adults with mild cognitive impairment

PURPOSE

Although physical exercise may improve memory in older adults, whether the Chinese traditional fitness exercise Wuqinxi improves working memory and delays cognitive deterioration in older adults with mild cognitive impairment (MCI) has not been assessed in randomized controlled experiments.

METHODS

Fifty older adults with MCI based on their Montreal Cognitive Assessment scores were randomized to either a Wuqinxi exercise group or a non-exercise control group. The exercise group engaged in Wuqinxi once a week for 60 min each session for 40 weeks. Participants in the control group received no intervention and maintained their regular living habits. The n-back paradigm was used to measure changes in working memory before and after Wuqinxi exercise.

RESULTS

In the 0-back task, the response speed of older adults with MCI who participated in Wuqinxi was faster than that of older adults with MCI in the non-exercise control group (P = 0.031); there was no significant difference in accuracy between the two groups (P > 0.05). In the 1-back and 2-back tasks, there was no significant difference in response times or in accuracy between the two groups (P > 0.05).

CONCLUSIONS

In this randomized controlled study, participation in long-term Wuqinxi delayed the deterioration of working memory in older adults with MCI, suggesting that this exercise may be an effective intervention to delay or prevent the progression of MCI to Alzheimer's disease.

Bidirectional association between executive and physical functions among older adults: A systematic review

OBJECTIVE

We aimed to examine the bidirectional associations between specific executive function (EF) and physical function (PF) subdomains among older adults.

METHODS

A systematic literature search (MEDLINE, EMBASE, PsycINFO, EBSCOHOST, Scopus and EmCare) was undertaken from February 2018 to May 2020. Observational studies measuring associations between EF and PF subdomains among older adults were included.

RESULTS

Twenty-nine studies met the inclusion criteria. Twenty-seven studies reported associations between EF and PF. There were bidirectional associations between slower processing speed and slower gait speed; slower processing speed and lower muscle strength; and lower verbal fluency and slower gait speed. Lower muscle strength was unilaterally associated with lower working memory.

CONCLUSIONS

We found consistent bidirectional associations between processing speed with gait speed and muscle strength, and verbal fluency and gait speed. There was a unidirectional association between muscle strength and working memory. Common causal mechanisms for EF and PF require further studies.

Higher VO2max is associated with thicker cortex and lower grey matter blood flow in older adults

VO₂max (maximal oxygen consumption), a validated measure of aerobic fitness, has been associated with better cerebral artery compliance and measures of brain morphology, such as higher cortical thickness (CT) in frontal, temporal and cingular cortices, and larger grey matter volume (GMV) of the middle temporal gyrus, hippocampus, orbitofrontal cortex and cingulate cortex. Single sessions of physical exercise can promptly enhance cognitive performance and brain activity during executive tasks. However, the immediate effects of exercise on macro-scale properties of the brain’s grey matter remain unclear. We investigated the impact of one session of moderate-intensity physical exercise, compared with rest, on grey matter volume, cortical thickness, working memory performance, and task-related brain activity in older adults. Cross-sectional associations between brain measures and VO₂max were also tested. Exercise did not induce statistically significant changes in brain activity, grey matter volume, or cortical thickness. Cardiovascular fitness, measured by VO₂max, was associated with lower grey matter blood flow in the left hippocampus and thicker cortex in the left superior temporal gyrus. Cortical thickness was reduced at post-test independent of exercise/rest. Our findings support that (1) fitter individuals may need lower grey matter blood flow to meet metabolic oxygen demand, and (2) have thicker cortex.

A Randomized Controlled Trial of High-Intensity Exercise and Executive Functioning in Cognitively Normal Older Adults

BACKGROUND

There is a paucity of interventional research that systematically assesses the role of exercise intensity and cardiorespiratory fitness, and their relationship with executive function in older adults. To address this limitation, we have examined the effect of a systematically manipulated exercise intervention on executive function.

METHODS

Ninety-nine cognitively normal participants (age = 69.10 ± 5.2 years; n = 54 female) were randomized into either a high-intensity cycle-based exercise, moderate-intensity cycle-based exercise, or no-intervention control group. All participants underwent neuropsychological testing and fitness assessment at baseline (preintervention), 6-month follow-up (postintervention), and 12-month postintervention. Executive function was measured comprehensively, including measures of each subdomain: Shifting, Updating/ Working Memory, Inhibition, Verbal Generativity, and Nonverbal Reasoning. Cardiorespiratory fitness was measured by analysis of peak aerobic capacity; VO₂peak.

RESULTS

First, the exercise intervention was found to increase cardiorespiratory fitness (VO₂peak) in the intervention groups, in comparison to the control group (F =10.40, p≤0.01). However, the authors failed to find mean differences in executive function scores between the high-intensity, moderate intensity, or inactive control group. On the basis of change scores, cardiorespiratory fitness was found to associate positively with the executive function (EF) subdomains of Updating/Working Memory (β = 0.37, p = 0.01, r = 0.34) and Verbal Generativity (β = 0.30, p = 0.03, r = 0.28) for intervention, but not control participants.

CONCLUSION

At the aggregate level, the authors failed to find evidence that 6-months of high-intensity aerobic exercise improves EF in older adults. However, it remains possible that individual differences in experimentally induced changes in cardiorespiratory fitness may be associated with changes in Updating/ Working Memory and Verbal Generativity.

Immediate effects of a single session of physical exercise on cognition and cerebral blood flow: A randomized controlled study of older adults

BACKGROUND

Regular physical activity is beneficial for cognitive performance in older age. A single bout of aerobic physical exercise can transiently improve cognitive performance. Researchers have advanced improvements in cerebral circulation as a mediator of long-term effects of aerobic physical exercise on cognition, but the immediate effects of exercise on cognition and cerebral perfusion are not well characterized and the effects in older adults are largely unknown.

METHODS

Forty-nine older adults were randomized to a 30-min aerobic exercise at moderate intensity or relaxation. Groups were matched on age and cardiovascular fitness (VO2 max). Average Grey Matter Blood Flow (GMBF), measured by a pulsed arterial-spin labeling (pASL) magnetic resonance imaging (MRI) acquisition, and working memory performance, measured by figurative n-back tasks with increasing loads were assessed before and 7 min after exercising/resting.

RESULTS

Accuracy on the n-back task increased from before to after exercising/resting regardless of the type of activity. GMBF decreased after exercise, relative to the control (resting) group. In the exercise group, higher n-back performance after exercise was associated with lower GMBF in the right hippocampus, left medial frontal cortex and right orbitofrontal cortex, and higher cardiovascular fitness was associated with lower GMBF.

CONCLUSION

The decrease of GMBF reported in younger adults shortly after exercise also occurs in older adults and relates to cardiovascular fitness, potentially supporting the link between cardiovascular fitness and cerebrovascular reactivity in older age.

Physical Exercise Helped to Maintain and Restore Functioning in Chinese Older Adults With Mild Cognitive Impairment: A 5-Year Prospective Study of the Hong Kong Memory and Ageing Prospective Study (HK-MAPS)

OBJECTIVE

This study investigated the potential of physical exercise habit as a lifestyle modification against cognitive and functional decline at the community level.

METHODS

A total of 454 community-dwelling Chinese older adults without dementia participated in the Hong Kong Memory and Ageing Prospective Study at baseline and follow-up at 5 years. Their cognitive and functional performances were assessed by the Cantonese version of the Mini-Mental State Examination (CMMSE) and the Chinese version of Disability Assessment in Dementia (DAD). Hierarchical multiple regression analyses were performed to examine whether physical exercise was a significant predictor of the follow-up CMMSE and DAD scores after controlling for the covariates. Subgroup analyses were performed with a group of 127 participants with mild cognitive impairment at baseline.

RESULTS

Physical exercise habit was a significant predictor for both the follow-up CMMSE scores and DAD scores. Participants with exercise habits of 5 years or more showed better cognitive and functional performances at follow-up. Participants who picked up exercise habits only after the baseline assessment also demonstrated better functioning at follow-up. The same patterns were observed in the subgroup analyses with the mild cognitive impairment group.

CONCLUSION

Results suggested that prolonged exercise habit is required for positive effects on cognition to emerge, but benefits on functioning can be observed when individuals take up an exercise habit later in life or even after the beginning of cognitive decline. These findings are encouraging in promoting an exercise habit among older adults living in the community.

Physical Fitness in Older People Recently Diagnosed with Cognitive Impairment Compared to Older People Recently Discharged from Hospital

BACKGROUND/AIMS

There is evidence of an association between cognitive function and physical fitness. The aim of this study was to compare physical fitness in patients with cognitive impairment with a group of older people recently discharged from hospital.

METHODS

A cross-sectional study with 98 patients recently diagnosed with cognitive impairment and 115 patients recently discharged from hospital. Associations between the study group variable and different components in the Senior fitness test were examined, controlling for demographic factors and comorbidity.

RESULTS

The group recently diagnosed with cognitive impairment indicated poorer results on three of six physical fitness components (p < 0.05).

CONCLUSION

Older adults with cognitive impairment are in need of individually tailored physical activity programs to increase the level of physical fitness.

Trajectory of Mobility Decline by Type of Dementia

Cognitive and physical aspects of functionality are closely related. However, whether physical decline differs by dementia type and progression rate is debatable. To address these issues, we conducted a longitudinal study of 766 older adults whose physical performance and cognitive status were assessed annually with standard assessment tools [eg, Physical Performance Test, Clinical Dementia Rate (CDR)] for 8 years. Compared with participants who remained cognitively normal, those progressing to later-stage dementia (CDR=1) declined in their mobility by a factor of 2.82 (P<0.001), followed by those who maintained a later-stage diagnosis (slope=-1.84, P<0.001), those progressing from early-stage to later-stage (CDR=0.5 to CDR=1) dementia (slope=-1.20, P<0.001), and those who progressed to early-stage dementia (slope=-0.39, P=0.038) suggesting a steeper physical decline with dementia progression, particularly in those with the fastest disease progression. Although all types of dementia experienced mobility decline, those progressing to non-Alzheimer disease (AD) dementias, especially vascular dementia declined faster than those who remained normal (slope=-2.70, P<0.001) or progressed to AD (slope=-2.18, P<0.001). These associations were better captured by the gait/balance component of physical functionality. Our findings suggest that rapidly progressing dementia patients particularly those with non-AD subtypes should be targeted for interventions to maintain or improve gait/balance and prevent functional decline and disability although AD patients may also benefit.

Physical Fitness and Serum Vitamin D and Cognition in Elderly Koreans

Poor physical fitness and low serum vitamin D are known to be modifiable risk factors for cognitive declines with normal aging. We investigated the association of physical fitness and serum vitamin D levels with global cognitive function in older adults. In this cross-sectional study, a total of 412 older Korean adults (108 men aged 74.4 ± 6.0 years and 304 women aged 73.1 ± 5.4 years) completed the Korean version of Mini-Mental State Examination (MMSE) to assess global cognitive performance and the senior fitness test to assess strength, flexibility, agility, and endurance domains of physical fitness. Body mass index, percent body fat, serum vitamin D, geriatric depression scale (GDS), level of education, smoking, and history of cardiovascular or cerebrovascular disease were also assessed as covariates. Age, sex, GDS, and body fatness were negatively associated with MMSE-based cognitive performance. Serum vitamin D and physical fitness were positively associated with MMSE-based cognitive performance. Multivariate linear regression showed that agility (partial R(2) = -0.184, p = 0.029) and endurance (partial R(2) = 0.191, p = 0.022) domains of physical fitness along with serum vitamin D (partial R(2) = 0.210, p = 0.012) were significant predictors for global cognitive performance after controlling for covariates (i.e., age, sex, education, GDS, body fatness, and comorbidity index). The current findings of the study suggest that promotion of physical fitness and vitamin D supplementation should be key components of interventions to prevent cognitive decline with normal aging. Key pointsCognitive declines are associated with normal aging as well as modifiable lifestyle risk factors, and there is an increasing need to identify the modifiable risk factors for the onset of cognitive declines and to provide evidence-based strategies for healthy and successful aging.In Korea, little is known about the relationships of physical fitness and serum vitamin D with cognitive function in older adults, and we determined the associations between a) serum vitamin D levels and cognitive function and b) physical fitness and cognitive function among community-dwelling elderly Koreans.The current findings of the study suggest that agility and endurance domains of physical fitness along with serum vitamin D were significant predictors for global cognitive performance after controlling for covariates.

Age Moderates the Association of Aerobic Exercise with Initial Learning of an Online Task Requiring Cognitive Control

The aim of this study was to examine whether people differed in change in performance across the first five blocks of an online flanker task and whether those trajectories of change were associated with self-reported aerobic or resistance exercise frequency according to age. A total of 8752 men and women aged 13-89 completed a lifestyle survey and five 45-s games (each game was a block of ~46 trials) of an online flanker task. Accuracy of the congruent and incongruent flanker stimuli was analyzed using latent class and growth curve modeling adjusting for time between blocks, whether the blocks occurred on the same or different days, education, smoking, sleep, caffeinated coffee and tea use, and Lumosity training status ("free play" or part of a "daily brain workout"). Aerobic and resistance exercise were unrelated to first block accuracies. For the more cognitively demanding incongruent flanker stimuli, aerobic activity was positively related to the linear increase in accuracy [B=0.577%, 95% confidence interval (CI), 0.112 to 1.25 per day above the weekly mean of 2.8 days] and inversely related to the quadratic deceleration of accuracy gains (B=-0.619% CI, -1.117 to -0.121 per day). An interaction of aerobic activity with age indicated that active participants younger than age 45 had a larger linear increase and a smaller quadratic deceleration compared to other participants. Age moderates the association between self-reported aerobic, but not self-reported resistance, exercise and changes in cognitive control that occur with practice during incongruent presentations across five blocks of a 45-s online, flanker task.

Balance and Mobility as Predictors of Post-Stroke Cognitive Impairment

Background

The number of patients with cognitive impairment following stroke is increasing due to the rise in the number of stroke survivors. Health authorities highlight the need for prediction and early diagnostics. The aims of this study were to investigate if balance and mobility may predict cognitive impairment 1 year after stroke.

Methods

The participants were patients with first-ever stroke or transient ischaemic attack (TIA). The exclusion criteria were pre-stroke cognitive impairment and dementia. Measurements of balance comprised the Berg Balance Scale (BBS) and the Figure of Eight test (Fig8). Mobility was measured by maximum walking speed and the Timed Up and Go test. Dementia and mild cognitive impairment were merged into a main outcome: cognitive impairment. Unadjusted and adjusted multivariate logistic regression models were performed.

Results

One hundred and eighty subjects performed balance and mobility measures at baseline, and 158 participated in the follow-up; 13 died and 9 did not complete the follow-up. Two variables made a significant contribution in the adjusted analyses (Fig8, BBS). The strongest predictor of cognitive impairment was Fig8 with an odds ratio of 1.06.

Conclusion

The results of Fig8 and BBS measured in the acute phase of stroke were predictors of cognitive impairment 1 year later in this cohort of first-ever stroke or TIA.