A single session of exercise increases connectivity in sensorimotor-related brain networks: a resting-state fMRI study in young healthy adults

Habitual long term physical activity is known to have beneficial cognitive, structural, and neuro-protective brain effects, but to date there is limited knowledge on whether a single session of exercise can alter the brain's functional connectivity, as assessed by resting-state functional magnetic resonance imaging (rs-fMRI). The primary objective of this study was to characterize potential session effects in resting-state networks (RSNs). We examined the acute effects of exercise on the functional connectivity of young healthy adults (N = 15) by collecting rs-fMRI before and after 20 min of moderate intensity aerobic exercise and compared this with a no-exercise control group (N = 15). Data were analyzed using independent component analysis, denoising and dual regression procedures. Regions of interest-based group session effect statistics were calculated in RSNs of interest using voxel-wise permutation testing and Cohen's D effect size. Group analysis in the exercising group data set revealed a session effect in sub-regions of three sensorimotor related areas: the pre and/or postcentral gyri, secondary somatosensory area and thalamus, characterized by increased co-activation after exercise (corrected p < 0.05). Cohen's D analysis also showed a significant effect of session in these three RSNs (p< 0.05), corroborating the voxel-wise findings. Analyses of the no-exercise dataset produced no significant results, thereby providing support for the exercise findings and establishing the inherent test-retest reliability of the analysis pipeline on the RSNs of interest. This study establishes the feasibility of rs-fMRI to localize brain regions that are associated with acute exercise, as well as an analysis consideration to improve sensitivity to a session effect.

Impact of a single bout of aerobic exercise on regional brain perfusion and activation responses in healthy young adults

Purpose

Despite the generally accepted view that aerobic exercise can have positive effects on brain health, few studies have measured brain responses to exercise over a short time span. The purpose of this study was to examine the impact within one hour of a single bout of exercise on brain perfusion and neuronal activation.

Methods

Healthy adults (n = 16; age range: 20–35 yrs) were scanned using Magnetic Resonance Imaging (MRI) before and after 20 minutes of exercise at 70% of their age-predicted maximal heart rate. Pseudo-continuous arterial spin labeling (pcASL) was used to measure absolute cerebral blood flow (CBF) prior to exercise (pre) and at 10 min (post-10) and 40 min (post-40) post-exercise. Blood oxygenation level dependent (BOLD) functional MRI (fMRI) was performed pre and post-exercise to characterize activation differences related to a go/no-go reaction time task.

Results

Compared to pre-exercise levels, grey matter CBF was 11% (±9%) lower at post-10 (P<0.0004) and not different at post-40 (P = 0.12), while global WM CBF was increased at both time points post-exercise (P<0.0006). Regionally, the hippocampus and insula showed a decrease in perfusion in ROI-analysis at post-10 (P<0.005, FDR corrected), whereas voxel-wise analysis identified elevated perfusion in the left medial postcentral gyrus at post-40 compared to pre (p_corrected = 0.05). BOLD activations were consistent between sessions, however, the left parietal operculum showed reduced BOLD activation after exercise.

Conclusion

This study provides preliminary evidence of regionalized brain effects associated with a single bout of aerobic exercise. The observed acute cerebrovascular responses may provide some insight into the brain’s ability to change in relation to chronic interventions.

Criterion and convergent validity of the Montreal cognitive assessment with screening and standardized neuropsychological testing

OBJECTIVES

To compare the validity of the Montreal Cognitive Assessment (MoCA) with the criterion standard of standardized neuropsychological testing and to compare the convergent validity of the MoCA with that of existing screening tools and global measures of cognition.

DESIGN

Cross-sectional observational study.

SETTING

Tertiary care hospital-based cognitive neurology subspecialty clinic.

PARTICIPANTS

A convenience sample of 107 individuals with mild Alzheimer's disease (AD, n=75) or mild cognitive impairment (MCI, n=32) from the Sunnybrook Dementia Study.

MEASUREMENTS

In addition to the MoCA, all participants completed the Mini-Mental State Examination (MMSE), the Mattis Dementia Rating Scale (DRS), and detailed neuropsychological testing.

RESULTS

Convergent validity was supported, with MoCA scores correlating well with the MMSE (correlation coefficient (r)=0.66, P<.001) and the DRS (r=0.77, P<.001) and the MoCA better associated with the DRS than did the MMSE. Criterion validity was supported, with MoCA subscores according to cognitive domain correlating well with analogous neuropsychological tests and, in the case of memory (area under the receiver operating characteristic curve (AUC)=0.86), executive (AUC=0.79), and visuospatial function (AUC=0.79), being reasonably sensitive to impairment in those domains.

CONCLUSION

The MoCA is a valid assessment of cognition that shows good agreement with existing screening tools and global measures (convergent validity) and was superior to the MMSE in this regard. The MoCA domain-specific subscores align with performance on more-detailed neuropsychological tests, suggesting not only good criterion validity for the MoCA, but also that it may be useful in guiding further neuropsychological testing.

The Mental Activity and eXercise (MAX) trial: a randomized controlled trial to enhance cognitive function in older adults

IMPORTANCE

The prevalence of cognitive impairment and dementia are projected to rise dramatically during the next 40 years, and strategies for maintaining cognitive function with age are critically needed. Physical or mental activity alone result in relatively small, domain-specific improvements in cognitive function in older adults; combined interventions may have more global effects.

OBJECTIVE

To examine the combined effects of physical plus mental activity on cognitive function in older adults.

DESIGN

Randomized controlled trial with a factorial design.

SETTING

San Francisco, California.

PARTICIPANTS

A total of 126 inactive, community-residing older adults with cognitive complaints.

INTERVENTIONS

All participants engaged in home-based mental activity (1 h/d, 3 d/wk) plus class-based physical activity (1 h/d, 3 d/wk) for 12 weeks and were randomized to either mental activity intervention (MA-I; intensive computer) or mental activity control (MA-C; educational DVDs) plus exercise intervention (EX-I; aerobic) or exercise control (EX-C; stretching and toning); a 2 × 2 factorial design was used so that there were 4 groups: MA-I/EX-I, MA-I/EX-C, MA-C/EX-1, and MA-C/EX-C.

MAIN OUTCOME MEASURES

Global cognitive change based on a comprehensive neuropsychological test battery.

RESULTS

Participants had a mean age of 73.4 years; 62.7% were women, and 34.9% were Hispanic or nonwhite. There were no significant differences between the groups at baseline. Global cognitive scores improved significantly over time (mean, 0.16 SD; P < .001) but did not differ between groups in the comparison between MA-I and MA-C (ignoring exercise, P = .17), the comparison between EX-I and EX-C (ignoring mental activity, P = .74), or across all 4 randomization groups (P = .26).

CONCLUSIONS AND RELEVANCE

In inactive older adults with cognitive complaints, 12 weeks of physical plus mental activity was associated with significant improvements in global cognitive function with no evidence of difference between intervention and active control groups. These findings may reflect practice effects or may suggest that the amount of activity is more important than the type in this subject population.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00522899.

Physical activity in the prevention of ischemic stroke and improvement of outcomes: a narrative review

Physical activity is an integral component of stroke prevention. Although approximately 80% of strokes are due to cerebral ischemia, the mechanisms linking physical activity to the incidence of and recovery from ischemic stroke are not completely understood. This review summarizes evidence from human and animal studies regarding physical activity in the prevention of overt and covert ischemic stroke and associated injury. In cohort studies, people who are physically active have reduced rates of overt ischemic stroke and ischemic stroke mortality. However, few human studies have examined physical activity and the incidence of covert stroke. Evidence from animal models of ischemic stroke indicates that physical activity reduces injury after ischemic stroke by reducing infarct size and apoptotic cell death. Accordingly, physical activity may reduce the magnitude of injury from ischemic stroke so that there are fewer or less severe symptoms. Future research should investigate physical activity and incidence of covert stroke prospectively, ascertain the optimal dose and type of exercise to prevent ischemic injury, and identify the underlying neuroprotective mechanisms.

Neuropathologic features associated with Alzheimer disease diagnosis: age matters

OBJECTIVE

To examine whether the association between clinical Alzheimer disease (AD) diagnosis and neuropathology and the precision by which neuropathology differentiates people with clinical AD from those with normal cognition varies by age.

METHODS

We conducted a cross-sectional analysis of 2,014 older adults (≥70 years at death) from the National Alzheimer's Coordinating Center database with clinical diagnosis of normal cognition (made ≤1 year before death, n = 419) or AD (at ≥65 years, n = 1,595) and a postmortem neuropathologic examination evaluating AD pathology (neurofibrillary tangles, neuritic plaques) and non-AD pathology (diffuse plaques, amyloid angiopathy, Lewy bodies, macrovascular disease, microvascular disease). We used adjusted logistic regression to analyze the relationship between clinical AD diagnosis and neuropathologic features, area under the receiver operating characteristic curve (c statistic) to evaluate how precisely neuropathology differentiates between cognitive diagnoses, and an interaction to identify effect modification by age group.

RESULTS

In a model controlling for coexisting neuropathologic features, the relationship between clinical AD diagnosis and neurofibrillary tangles was significantly weaker with increasing age (p < 0.001 for interaction). The aggregate of all neuropathologic features more strongly differentiated people with clinical AD from those without in younger age groups (70-74 years: c statistic, 95% confidence interval: 0.93, 0.89-0.96; 75-84 years: 0.95, 0.87-0.95; ≥85 years: 0.83, 0.80-0.87). Non-AD pathology significantly improved precision of differentiation across all age groups (p < 0.004).

CONCLUSION

Clinical AD diagnosis was more weakly associated with neurofibrillary tangles among the oldest old compared to younger age groups, possibly due to less accurate clinical diagnosis, better neurocompensation, or unaccounted pathology among the oldest old.

Activity energy expenditure and incident cognitive impairment in older adults

BACKGROUND

Studies suggest that physically active people have reduced risk of incident cognitive impairment in late life. However, these studies are limited by reliance on self-reports of physical activity, which only moderately correlate with objective measures and often exclude activity not readily quantifiable by frequency and duration. The objective of this study was to investigate the relationship between activity energy expenditure (AEE), an objective measure of total activity, and incidence of cognitive impairment.

METHODS

We calculated AEE as 90% of total energy expenditure (assessed during 2 weeks using doubly labeled water) minus resting metabolic rate (measured using indirect calorimetry) in 197 men and women (mean age, 74.8 years) who were free of mobility and cognitive impairments at study baseline (1998-1999). Cognitive function was assessed at baseline and 2 or 5 years later using the Modified Mini-Mental State Examination. Cognitive impairment was defined as a decline of at least 1.0 SD (9 points) between baseline and follow-up evaluations.

RESULTS

After adjustment for baseline Modified Mini-Mental State Examination scores, demographics, fat-free mass, sleep duration, self-reported health, and diabetes mellitus, older adults in the highest sex-specific tertile of AEE had lower odds of incident cognitive impairment than those in the lowest tertile (odds ratio, 0.09; 95% confidence interval, 0.01-0.79). There was also a significant dose response between AEE and incidence of cognitive impairment (P = .05 for trend over tertiles).

CONCLUSIONS

These findings indicate that greater AEE may be protective against cognitive impairment in a dose-response manner. The significance of overall activity in contrast to vigorous or light activity should be determined.

Mild cognitive impairment, dementia, and their subtypes in oldest old women

BACKGROUND

The population of oldest old is increasing, but the prevalence of cognitive impairment is not well characterized in this group.

OBJECTIVES

To determine the prevalence of mild cognitive impairment (MCI), dementia, and their subtypes in oldest old women and to examine whether some groups of oldest old women were more likely to have cognitive impairment.

DESIGN

Prospective cohort study.

SETTING

Women Cognitive Impairment Study of Exceptional Aging.

PARTICIPANTS

A total of 1299 oldest old (≥85 years) women.

MAIN OUTCOME MEASURES

All the women completed a neuropsychological test battery. Those who screened positive for possible cognitive impairment (n = 634) were further assessed for a diagnosis of dementia, MCI, or normal cognition. The remaining women (n = 665) were considered cognitively normal. Dementia and MCI subtypes were determined using standard criteria.

RESULTS

The women had a mean age of 88.2 years, and 27.0% were 90 years or older; 231 women (17.8%) were diagnosed as having dementia and 301 (23.2%) as having MCI, for a combined cognitive impairment prevalence of 41.0%. Clinical features consistent with Alzheimer disease and mixed dementia were most common, each accounting for 40% of dementia cases. Amnestic multiple domain and nonamnestic single domain were the most common MCI types, accounting for 33.9% and 28.9% of cases, respectively. Cognitive impairment was more frequent in women 90 years or older compared with those 85 to 89 years (dementia, 28.2% vs 13.9%, P < .001; MCI, 24.5% vs 22.7%, P = .02) and was more common in women with less education, a history of stroke, and prevalent depression.

CONCLUSIONS

In this large sample of oldest old women, 41.0% had clinically adjudicated cognitive impairment. Subtypes of dementia and MCI were similar to those in younger populations. Women in the fastest growing demographic, the oldest old, should be screened for cognitive disorders, especially high-risk groups.

Physical activity over the life course and its association with cognitive performance and impairment in old age

OBJECTIVE

To determine how physical activity at various ages over the life course is associated with cognitive impairment in late life.

DESIGN

Cross-sectional study.

SETTING

Four U.S. sites.

PARTICIPANTS

Nine thousand three hundred forty-four women aged 65 and older (mean 71.6) who self-reported teenage, age 30, age 50, and late-life physical activity.

MEASUREMENTS

Logistic regression was used to determine the association between physical activity status at each age and likelihood of cognitive impairment (modified Mini-Mental State Examination (mMMSE) score >1.5 standard deviations below the mean, mMMSE score</=22). Models were adjusted for age, education, marital status, diabetes mellitus, hypertension, depressive symptoms, smoking, and body mass index.

RESULTS

Women who reported being physically active had a lower prevalence of cognitive impairment in late life than women who were inactive at each time (teenage: 8.5% vs 16.7%, adjusted odds ratio (AOR)=0.65, 95% confidence interval (CI)=0.53-0.80; age 30: 8.9% vs 12.0%, AOR=0.80, 95% CI=0.67-0.96); age 50: 8.5% vs 13.1%, AOR=0.71, 95% CI=0.59-0.85; old age: 8.2% vs 15.9%, AOR=0.74, 95% CI=0.61-0.91). When the four times were analyzed together, teenage physical activity was most strongly associated with lower odds of late-life cognitive impairment (OR=0.73, 95% CI=0.58-0.92). However, women who were physically inactive as teenagers and became active in later life had lower risk than those who remained inactive.

CONCLUSIONS

Women who reported being physically active at any point over the life course, especially as teenagers, had a lower likelihood of cognitive impairment in late life. Interventions should promote physical activity early in life and throughout the life course.

The inclusion of cognition in vascular risk factor clinical practice guidelines

BACKGROUND

People with vascular risk factors are at increased risk for cognitive impairment as well as vascular disease. The objective of this study was to evaluate whether vascular risk factor clinical practice guidelines consider cognition as an outcome or in connection with treatment compliance.

METHODS

Articles from PubMed, EMBASE, and the Cochrane Library were assessed by at least two reviewers and were included if: (1) Either hypertension, high cholesterol, diabetes, or atrial fibrillation was targeted; (2) The guideline was directed at physicians; (3) Adult patients (aged 19 years or older) were targeted; and (4) The guideline was published in English. Of 91 guidelines, most were excluded because they were duplicates, older versions, or focused on single outcomes.

RESULTS

Of the 20 clinical practice guidelines that met inclusion criteria, five mentioned cognition. Of these five, four described potential treatment benefits but only two mentioned that cognition may affect compliance. No guidelines adequately described how to screen for cognitive impairment.

CONCLUSION

Despite evidence that links cognitive impairment to vascular risk factors, only a minority of clinical practice guidelines for the treatment of vascular risk factors consider cognition as either an adverse outcome or as a factor to consider in treatment.

Changes in cognition and mortality in relation to exercise in late life: a population based study

Background

On average, cognition declines with age but this average hides considerable variability, including the chance of improvement. Here, we investigate how exercise is associated with cognitive change and mortality in older people and, particularly, whether exercise might paradoxically increase the risk of dementia by allowing people to live longer.

Methods and Principal Findings

In the Canadian Study of Health and Aging (CSHA), of 8403 people who had baseline cognition measured and exercise reported at CSHA-1, 2219 had died and 5376 were re-examined at CSHA-2. We used a parametric Markov chain model to estimate the probabilities of cognitive improvement, decline, and death, adjusted for age and education, from any cognitive state as measured by the Modified Mini-Mental State Examination. High exercisers (at least three times per week, at least as intense as walking, n = 3264) had more frequent stable or improved cognition (42.3%, 95% confidence interval: 40.6–44.0) over 5 years than did low/no exercisers (all other exercisers and non exercisers, n = 4331) (27.8% (95% CI 26.4–29.2)). The difference widened as baseline cognition worsened. The proportion whose cognition declined was higher amongst the high exercisers but was more similar between exercise groups (39.4% (95% CI 37.7–41.1) for high exercisers versus 34.8% (95% CI 33.4–36.2) otherwise). People who did not exercise were also more likely to die (37.5% (95% CI 36.0–39.0) versus 18.3% (95% CI 16.9–19.7)). Even so, exercise conferred its greatest mortality benefit to people with the highest baseline cognition.

Conclusions

Exercise is strongly associated with improving cognition. As the majority of mortality benefit of exercise is at the highest level of cognition, and declines as cognition declines, the net effect of exercise should be to improve cognition at the population level, even with more people living longer.

Exercise: a potential contributing factor to the relationship between folate and dementia

OBJECTIVES

To investigate whether exercise confounds the relationship between folate and cerebrovascular events, all-cause dementia, and Alzheimer's disease.

DESIGN

Prospective cohort study.

SETTING

Multiple centers in Canada.

PARTICIPANTS

In the Canadian Study of Health and Aging, 466 people reported exercise levels, had folate measurements, and were not demented at baseline. After 5 years, 194 had adverse cerebrovascular events, and 65 had dementia (Alzheimer's disease in 47).

MEASUREMENTS

Associations between folate and cerebrovascular outcomes were examined using logistic regression in the presence and absence of exercise and other confounders.

RESULTS

Folate was associated with greater risk of Alzheimer's disease (odds ratio (OR)=2.12, 95% confidence interval (CI)=1.01-4.54) and cerebrovascular outcomes (OR=2.05, 95% CI=1.11-3.78) in adjusted analyses before the inclusion of exercise and neared significance with all-cause dementia (OR=1.80, 95% CI=0.94-3.45). After the inclusion of exercise, the association between folate and dementia and Alzheimer's disease was 29% and 25% lower, respectively, and neither association was any longer significant (Alzheimer's disease: OR=1.91, 95% CI=0.89-4.11; all-cause dementia: OR=1.62, 95% CI=0.84-3.15). Exercise was a significant confounder in the relationship between folate and Alzheimer's disease (P=.03) and dementia (P=.003) but not cerebrovascular outcomes (P=.64). Unlike folate, exercise was significantly associated with Alzheimer's disease (OR=0.43, 95% CI=0.19-0.98) and dementia (OR=0.35, 95% CI=0.17-0.72) in adjusted analyses.

CONCLUSION

Exercise seems to account for much of the relationship between folate and incident dementia and Alzheimer's disease.

Effects of menstrual phase on performance and recovery in intense intermittent activity

Game sport and training require repeated high intensity bursts. This study examined differences between high intensity, intermittent work in two phases of the menstrual cycle. Six physically active young women (age 19-29) performed 10 6-s sprints on a cycle ergometer in both the mid-follicular (FP) (days 6-10) and late-luteal phases (LP) (days 20-24) of the menstrual cycle. Work, power, oxygen intake (VO2) parameters, and capillarized blood lactate were measured. Data are analyzed using the Friedman and Wilcoxon matched pairs tests. There was no difference between menstrual phases in peak 6-s power (6.8(0.6) W kg(-1) in FP, 6.9(0.6) W kg(-1) in LP), the drop off in work (1.2(3.5) J kg(-1) in FP and 1.0(2.7) J kg(-1) in LP), or in the sprint VO2 (23.7(1.5) mL kg(-1) min(-1) in LP and 24.3(2.4) mL kg(-1) min(-1) in FP). Capillarized blood lactate was also similar in both phases of the menstrual cycle both at 1 min (9.2(2.7) mmol L(-1) in FP, 9.2(3.1) mmol L(-1)) and at 3 min (9.0(2.2) mmol L(-1) in FP, 9.2(2.2) mmol L(-1) in LP). However, the average 6-s work was greater in the LP (39.3(3.4) J kg(-1)) than during the FP (38.3(3.1) J kg(-1)) (P=0.023). The recovery VO2 was also greater in the LP than the FP (26.3(2.4) mL kg(-1) min(-1) in LP, 25.0(2.6) mL kg(-1) min(-1) in FP, P=0.023). Average work over a series of sprints and the VO2 consumed between sprints may be slightly greater during the LP than the FP of the menstrual cycle.