Physical Activity in Preventing Alzheimer’s Disease and Cognitive Decline: A Narrative Review

Physical Activity Moderates the Relationship between Cardiovascular Disease Risk Burden and Cognition in Older Adults

INTRODUCTION

Older individuals with a higher cardiovascular disease (CVD) burden have a higher risk for accelerated cognitive decline and dementia. Physical activity (PA) is an inexpensive and accessible preventive measure to CVD, cognitive impairment, and dementia. The current study examined (1) whether PA moderates the relationship between CVD burden and cognition and (2) whether the moderating effect of PA differs by race/ethnicity groups and by APOE-ɛ4 status.

METHODS

Our cross-sectional study included participants from the Washington Heights-Inwood Columbia Aging Project (WHICAP), a multiethnic, community-based, longitudinal study on aging and dementia among individuals aged 65 years and older who reside in northern Manhattan. All participants underwent an interview and a neuropsychological assessment for global cognition, memory, language, visuospatial, and speed functioning.

RESULTS

In 2,122 older individuals without dementia, having a higher CVD burden was associated with worse cognitive scores for global, language, speed, and visuospatial cognitive functions. PA mitigated the relationship between CVD burden and visuospatial function. Furthermore, PA mitigated the association of CVD burden with global cognition, language, and visuospatial functions in APOE-ɛ4 carriers but not in non-carriers.

DISCUSSION/CONCLUSION

Our study suggests that PA may mitigate the negative association between CVD and cognition, especially in APOE-ɛ4 carriers. The moderating effect of PA did not differ by race/ethnicity.

Efficacy of virtual reality technology interventions for cognitive and mental outcomes in older people with cognitive disorders: An umbrella review comprising meta-analyses of randomized controlled trials

We conducted an umbrella review of virtual reality (VR) technology interventions and cognitive improvement in older adults with cognitive disorders to establish a hierarchy of evidence. We systematically searched PubMed, Web of Science, Scopus, and PsycINFO databases from database creation to February 2023. We included meta-analyses relevant to our study objectives for the overall review. We assessed the methodological quality according to AMSTAR2, and we used the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) method to assess the credibility of the evidence. This overall review was registered with the International Prospective Register of Systematic Reviews (CRD42023423063). We identified six meta-analyses that included 12 cognitive outcomes, but only memory (Standardized Mean Difference(SMD) = 0.27, 95% confidence interval (CI): 0.04 to 0.49), depression (SMD = -1.26, 95% CI: -1.8 to -0.72), and global cognition (SMD = 0.42, 95% CI: 0.18 to 0.66) improved through the VR technology intervention. Using the 95% prediction interval (PI) results, we found that VR technology did not significantly affect the cognitive abilities of people with cognitive decline despite increasing the subject size. We conclude that the VR technology intervention improved only specific cognitive abilities.

Effects of exercise interventions on cognitive functions in healthy populations: A systematic review and meta-analysis

Chronic exercise intervention is a non-pharmacological therapy suggested to improve cognitive function in various populations. However, few meta-analyses have assessed the cognitive benefits associated with all FITT-VP variables (exercise frequency, intensity, bout duration time, type, volume or total intervention length, and progression) in healthy populations by age. Thus, this meta-analysis assessed the effects of each FITT-VP variable on cognitive function in healthy children, adults, and older adults. This study followed PRISMA guidelines. After searching PubMed and the Web of Science, we included 54 randomized controlled trials to examined the effects of FITT-VP variables on five cognitive domains: global cognition, executive function, memory, attention, and information processing. Moderation analyses assessed the effects by age and by each exercise variables. Exercise benefitted overall cognition and all subcognitive domains. Aerobic and resistance exercise showed the greatest benefits on global cognition and executive function respectively, whereas mind-body exercise benefitted memory. Among all populations, older adults showed the greatest benefits of exercise on global cognition, executive function, and memory compared with controls. Additional studies are needed to assess the effects of exercise on attention and information processing. This meta-analysis offers new insights on the relationships between cognition and FITT-VP exercise variables in healthy populations.

Effect of physical activity on risk of Alzheimer's disease: A systematic review and meta-analysis of twenty-nine prospective cohort studies

OBJECTIVE

Physical activity (PA) is beneficial in reductions of all-cause mortality and dementia. However, whether Alzheimer's disease (AD) risk is modified by PA remains disputable. This meta-analysis aims to disclose the underlying relationship between PA and incident AD.

METHODS

Pubmed, Embase, Cochrane Library, and Web of Science were retrieved from inception to June 2023. Random-effects models were employed to derive the effect size, represented by hazard ratio (HR) and 95% confidence interval (CI).

RESULTS

Twenty-nine prospective cohort studies involving 2068,519 participants were included. The pooled estimate showed a favorable effect of PA on AD risk decline (HR 0.72, 95% CI 0.65-0.80). This association remained robust after adjusting for maximum confounders (HR 0.85, 95% CI 0.79-0.91). Subgroup analysis of PA intensity demonstrated an inverse dose-response relationship between PA and AD, effect sizes of which were significant in moderate (HR 0.85, 95% CI 0.80-0.93) and high PA (HR 0.56, 95% CI 0.45-0.68), but not in low PA (HR 0.94, 95% CI 0.77-1.15). Regardless of all participants or the mid-life cohort, the protection of PA against AD appeared to be valid in shorter follow-up (<15 years) rather than longer follow-up (≥15 years). In addition to follow-up, the robustness of the estimates persisted in supplementary meta-analyses, meta-regression analyses, and sensitivity analyses.

CONCLUSION

PA intervention reduces the incidence of AD, but merely in moderate to vigorous PA with follow-up of less than 15 years, thus conditionally recommending the popularization of PA as a modifiable lifestyle factor to prevent AD.

Lipids, Gut Microbiota, and the Complex Relationship with Alzheimer's Disease: A Narrative Review

Alzheimer's Disease (AD) is a multifactorial, progressive, and chronic neurodegenerative disorder associated with the aging process. Memory deficits, cognitive impairment, and motor dysfunction are characteristics of AD. It is estimated that, by 2050, 131.5 million people will have AD. There is evidence that the gastrointestinal microbiome and diet may contribute to the development of AD or act preventively. Communication between the brain and the intestine occurs through immune cells in the mucosa and endocrine cells, or via the vagus nerve. Aging promotes intestinal dysbiosis, characterized by an increase in pro-inflammatory pathogenic bacteria and a reduction in anti-inflammatory response-mediating bacteria, thus contributing to neuroinflammation and neuronal damage, ultimately leading to cognitive decline. Therefore, the microbiota-gut-brain axis has a significant impact on neurodegenerative disorders. Lipids may play a preventive or contributory role in the development of AD. High consumption of saturated and trans fats can increase cortisol release and lead to other chronic diseases associated with AD. Conversely, low levels of omega-3 polyunsaturated fatty acids may be linked to neurodegenerative diseases. Unlike other studies, this review aims to describe, in an integrative way, the interaction between the gastrointestinal microbiome, lipids, and AD, providing valuable insights into how the relationship between these factors affects disease progression, contributing to prevention and treatment strategies.

Impact of multidomain preventive strategies on functional brain connectivity in older adults with cognitive complaint: Subset from the Montpellier center of the ancillary MAPT-MRI study

Introduction

The impact of multi-domain preventive interventions on older adults, in particular on those with higher risk to develop Alzheimer's disease (AD), could be beneficial, as it may delay cognitive decline. However, the precise mechanism of such positive impact is not fully understood and may involve brain reserve and adaptability of brain functional connectivity (FC).

Methods

To determine the effect of multidomain interventions (involving physical activity, cognitive training, nutritional counseling alone or in combination with omega-3 fatty acid supplementation and vs. a placebo) on the brain, longitudinal FC changes were assessed after 36 months of intervention on 100 older adults (above 70 year-old) with subjective cognitive complaints.

Results

No global change in FC was detected after uni or multidomain preventive interventions. However, an effect of omega-3 fatty acid supplementation dependent on cognitive decline status was underlined for frontoparietal, salience, visual and sensorimotor networks FC. These findings were independent of the cortical thickness and vascular burden.

Discussion

These results emphasize the importance of patient stratification, based on risk factors, for preventive interventions.

Trimethylamine N-oxide aggravated cognitive impairment from APP/PS1 mice and protective roles of voluntary exercise

To determine whether trimethylamine N-oxide (TMAO) would aggravate cognitive dysfunction from APP/PS1 mice and the potential protective effects of voluntary wheel running (VWR). TMAO impaired learning and memory abilities, and exercise reversed TMAO induced cognitive impairment. Serum TMAO, choline, betaine and TMA were significantly elevated from TMAO group, while exercise group had decreased TMAO, betaine and TMA level. TMAO group has significantly upregulated BACE1 from both hippocampus and cortex, also increased cathepsin B, p-Tau at Ser396&Ser404, GFAP, p-NF-κB p65 in cortex, while reduced BDNF, synaptophysin and PSD95 in hippocampus, also reduced occludin and ZO-1 from cortex, and reduced occludin from colon. In contrast, BACE1 from both hippocampus and cortex, also cathepsin B and p-Tauser396 from cortex were reduced, BDNF, snaptophysin, and PSD95 from hippocampus, ZO-1 from cortex, and occludin from colon were elevated post exercise compared to TMAO group. Exercise elevated α diversity index of cecal content, and TMAO and exercise affected gut microbiota profiles differentially. In conclusion, TMAO led to gut microbiota dysbiosis, impaired gut-brain integrity, elevated neuroinflammation, Aβ pathology and tau phosphorylation, disordered synaptic function; and exercise could reverse TMAO induced cognitive dysfunction via improving the above markers. The potential deleterious effects of TMAO on cognitive function need to be validated in humans, also dosages of exercise for exerting neuroprotective effects against TMAO induced cognitive impairment.

Effects of exercise interventions on executive function in old adults with mild cognitive impairment: A systematic review and meta-analysis of randomized controlled trials

AIMS

To assess the effect of exercise interventions on subdomains of executive function (EF) in older adults with mild cognitive impairment (MCI).

METHODS

Nine electronic databases were comprehensively searched from their inception to February 2021. Randomized controlled trials examining the effect of exercise training on EF in MCI were included.

RESULTS

Twenty-four eligible articles involving 2278 participants were identified. The results showed that exercise interventions had positive benefits on working memory, switching and inhibition in MCI. Subgroup analysis based on exercise prescriptions revealed that both aerobatic exercise and mind-body exercise had similar positive effect size on working memory. However, only mind-body exercise had significant effect on switching. Exercise training with moderate frequency (3-4 times/week) had larger effect size than low frequency (1-2 times/week) and only moderate frequency had positive benefits on switching. Both short (4-12 weeks), medium (13-24 weeks) and long (more than 24 weeks) exercise duration significantly ameliorate working memory and switching, however with short duration having slight larger effect sizes than medium and long.

CONCLUSION

Exercise significantly improves three subdomains of EF in MCI, especially mind-body exercise. Exercise training sticking to at least 4 weeks with 3-4 times a week tends to have larger effect size.

Dementia Prevention in Clinical Practice

Over 55 million people globally are living with dementia and, by 2050, this number is projected to increase to 131 million. This poses immeasurable challenges for patients and their families and a significant threat to domestic and global economies. Given this public health crisis and disappointing results from disease-modifying trials, there has been a recent shift in focus toward primary and secondary prevention strategies. Approximately 40% of Alzheimer's disease (AD) cases, which is the most common form of dementia, may be prevented or at least delayed. Success of risk reduction studies through addressing modifiable risk factors, in addition to the failure of most drug trials, lends support for personalized multidomain interventions rather than a "one-size-fits-all" approach. Evolving evidence supports early intervention in at-risk patients using individualized interventions directed at modifiable risk factors. Comprehensive risk stratification can be informed by emerging principals of precision medicine, and include expanded clinical and family history, anthropometric measurements, blood biomarkers, neurocognitive evaluation, and genetic information. Risk stratification is key in differentiating subtypes of dementia and identifies targetable areas for intervention. This article reviews a clinical approach toward dementia risk stratification and evidence-based prevention strategies, with a primary focus on AD.

The Prognostic Value of Domain-Specific Cognitive Abilities Assessed by Chinese Version of Oxford Cognitive Screen on Determining ADLs Recovery in Patients with Post-Stroke Cognitive Impairment

Background

Poststroke cognitive impairment (PSCI) has been increasingly recognized in patients. However, it remains unclear whether ADLs recovery is more susceptible to domain-specific cognitive abilities after a stroke. Therefore, the study was designed to investigate the cognitive functions of patients with PSCI at admission by using the Chinese (Putonghua) Version of the Oxford Cognitive Screen (OCS-P) as well as to identify the prognostic value of domain-specific cognitive abilities on the recovery of ADLs when discharged.

Methods

A total of 153 hospitalized stroke patients were included in this prospective study. Cognitive function was assessed by OCS-P when participants were admitted to the hospital. The ADLs were measured at admission and discharge, and recovery was estimated by the improvement between admission and discharge. A diagnostic model using logistic regression was constructed to identify the prognostic value of domain-specific cognitive abilities for ADLs. The efficacy and accuracy of the diagnostic model were assessed by receiver operating characteristic (ROC) and Hosmer-Lemeshow's goodness of fit test. The diagnostic model was validated by 10-fold cross-validation and presented as a nomogram.

Results

The score of OCS-P was 60(49.75, 69). The most frequently impaired cognitive domain was number writing (60.8%), followed by verbal memory (52.9%). Multivariate logistic regression showed executive dysfunction was a risk prognostic factor of ADLs recovery (P < 0.001, OR = 3.176 [95% CI, 1.218∼8.278]). The ROC curve of the diagnostic model was 0.839, with a good diagnostic efficacy. Hosmer–Lemeshow test showed diagnostic model had good calibration ability (χ² = 8.939.3, P=0.347 > 0.05). The average error rate after adjustment of 10-fold cross-validation was 20.93%, within the acceptable range.

Conclusions

Post-stroke patients generally suffered from multidimensional cognitive impairments. Executive dysfunction screened with OCS-P at clinical admission was a reliable and accessible predictive factor ADLs recovery in patients with PSCI. Early targeted rehabilitation programs are suggested to make them as earlier as possible, especially for those having executive dysfunction while hospitalized.

Relationship between Nutrition, Lifestyle, and Neurodegenerative Disease: Lessons from ADH1B, CYP1A2 and MTHFR

In the present review, the main features involved in the susceptibility and progression of neurodegenerative disorders (NDDs) have been discussed, with the purpose of highlighting their potential application for promoting the management and treatment of patients with NDDs. In particular, the impact of genetic and epigenetic factors, nutrients, and lifestyle will be presented, with particular emphasis on Alzheimer’s disease (AD) and Parkinson’s disease (PD). Metabolism, dietary habits, physical exercise and microbiota are part of a complex network that is crucial for brain function and preservation. This complex equilibrium can be disrupted by genetic, epigenetic, and environmental factors causing perturbations in central nervous system homeostasis, contributing thereby to neuroinflammation and neurodegeneration. Diet and physical activity can directly act on epigenetic modifications, which, in turn, alter the expression of specific genes involved in NDDs onset and progression. On this subject, the introduction of nutrigenomics shed light on the main molecular players involved in the modulation of health and disease status. In particular, the review presents data concerning the impact of ADH1B, CYP1A2, and MTHFR on the susceptibility and progression of NDDs (especially AD and PD) and how they may be exploited for developing precision medicine strategies for the disease treatment and management.

Spatial Olfactory Memory and Spatial Olfactory Navigation, Assessed with a Variant of Corsi Test, Is Modulated by Gender and Sporty Activity

Many studies have focused on navigation, spatial skills, and the olfactory system in comparative models, including those concerning the relationship between them and physical activity. Although the results are often in contrast with each other, it is assumed that physical activity can affect cognition in different ways—both indirectly and through a certain influence on some brain structures. In contrast, there is little research that focuses on the relationship between spatial abilities and olfactory abilities in humans. This research aimed to evaluate and compare the performance in working memory tasks of athletes and non-athletes who require good visual–spatial navigation, olfactory–spatial navigation, and olfactory–semantic skills. The study involved 236 participants (83 athletes) between the ages of 18 and 40. All subjects were matched by age or sex. The standard Corsi Block Tapping Test (CBTT) was administrated to investigate the visual-spatial memory. Olfactory–spatial navigation and olfactory–semantic skills were assessed with two modified versions of CBTT: Olfactory CBTT (OCBTT) and Semantic–Olfactory CBTT (SOCBTT) respectively. The results show differences between the CORSI conditions in direction of a poor performance for athletes. A gender effect in favor of men was also found, particularly in the classic version of the CBTT. Both groups performed better in the classic version of the CBTT than OCBTT and SOCBTT. The mean of SOCBTT results is markedly lower, perhaps due to the different information processing systems needed to perform this kind of task. It is possible to explain how sports practice can affect tasks that require spatial skills and olfactory perception differently, thus supporting new hypotheses and opening new scientific horizons.

Toxic Substance-induced Hippocampal Neurodegeneration in Rodents as Model of Alzheimer’s Dementia

BACKGROUND: Alzheimer’s Dementia (AD) cases are increasing with the global elderly population. To study the part of the brain affected by AD, animal models for hippocampal degeneration are still necessary to better understand AD pathogenesis and develop treatment and prevention measures. AIM: This study was a systematic review of toxic substance-induced animal models of AD using the Morris Water Maze method in determining hippocampal-related memory impairment. Our aim was reviewing the methods of AD induction using toxic substances in laboratory rodents and evaluating the report of the AD biomarkers reported in the models. METHODS: Data were obtained from articles in the PubMed database, then compiled, categorized, and analyzed. Eighty studies published in the past 5 years were included for analysis. RESULTS AND DISCUSSION: The most widely used method was intracerebroventricular injection of amyloid-β _substances. However, some less technically challenging techniques using oral or intraperitoneal administration of other toxic substances also produce successful models. Instead of hippocampal neurodegeneration, many studies detected biomarkers of the AD pathological process while some reported inflammation, oxidative stress, neurotrophic factors, and changes of cholinergic activity. Female animals were underrepresented despite a high incidence of AD in women. CONCLUSION: Toxic substances may be used to develop AD animal models characterized with appropriate AD pathological markers. Characterization of methods with the most easy-handling techniques and more studies in female animal models should be encouraged.

Is there a bidirectional association between sedentary behaviour and cognitive decline in older adults? Findings from the Irish Longitudinal Study on Ageing

Research on whether sedentary behaviour (SB) is related to cognitive decline in older individuals is conflicting, potentially caused by methodological differences in previous studies. To inform public health policies, we analysed both the forward and reverse association across four-years between subjective TV time and objectively-measured SB and four cognitive outcome measures in older adults. The Irish Longitudinal Study on Ageing (TILDA) quantified time spent watching TV using a questionnaire and objective physical activity patterns with a GENEActiv accelerometer. Mixed model analysis examined whether these two measures of SB related to changes in cognitive function (immediate and delayed recall, MMSE, and animal naming task) during a four-year follow-up period. Furthermore, the reverse association between changes in cognition over the preceding four years and SB was investigated. We included 1,276 participants (67 ± 9 years). Longitudinally, every hour of objective SB per day was associated with a -0.01 (95%CI = -0.03;-0.00) lower MMSE score per year. Reversely, a worse decline in immediate and delayed recall over the preceding waves was related to slightly more objective SB (B = -0.24 (95%CI = -0.41;-0.07)) and TV time (B = -0.25 (95%CI = -0.48;-0.03)) at the end of those four years. To conclude, in healthy older individuals, higher levels of objective SB are related to cognitive decline across a four-year follow-up, although the magnitude and clinical relevance are questionable. As preceding cognitive decline is associated with more SB across follow-up, this suggests that a bidirectional association is plausible.

The role of biofactors in the prevention and treatment of age-related diseases

The present demographic changes toward an aging society caused a rise in the number of senior citizens and the incidence and burden of age-related diseases (such as cardiovascular diseases [CVD], cancer, nonalcoholic fatty liver disease [NAFLD], diabetes mellitus, and dementia), of which nearly half is attributable to the population ≥60 years of age. Deficiencies in individual nutrients have been associated with increased risks for age-related diseases and high intakes and/or blood concentrations with risk reduction. Nutrition in general and the dietary intake of essential and nonessential biofactors is a major determinant of human health, the risk to develop age-related diseases, and ultimately of mortality in the older population. These biofactors can be a cost-effective strategy to prevent or, in some cases, even treat age-related diseases. Examples reviewed herein include omega-3 fatty acids and dietary fiber for the prevention of CVD, α-tocopherol (vitamin E) for the treatment of biopsy-proven nonalcoholic steatohepatitis, vitamin D for the prevention of neurodegenerative diseases, thiamine and α-lipoic acid for the treatment of diabetic neuropathy, and the role of folate in cancer epigenetics. This list of potentially helpful biofactors in the prevention and treatment of age-related diseases, however, is not exhaustive and many more examples exist. Furthermore, since there is currently no generally accepted definition of the term biofactors, we here propose a definition that, when adopted by scientists, will enable a harmonization and consistent use of the term in the scientific literature.

Biomarkers for evaluating the effects of exercise interventions in patients with MCI or dementia: A systematic review and meta-analysis

OBJECTIVES

To summarize the biomarkers for evaluating the effects of exercise interventions in patients with cognitive impairment associated with aging, as well as their responses to exercise interventions.

DESIGN

A systematic review and meta-analysis METHODS: We systematically searched different electronic database, including PubMed, Cochrane Central Register of Controlled Trials, Embase, Web of Science, PsycINFO, SPORTDiscus up to April 2020. Clinical controlled trials with exercise interventions in patients with cognitive impairment were included. The main outcomes included all the biomarkers used to evaluate the effects of exercise interventions. If data for certain biomarkers was enough (more than 2 studies), meta-analyses would be performed to estimate the effect sizes by calculating the standard mean differences (SMDs) and 95% confidence intervals (CIs).

RESULTS

Finally, we included 33 articles from 26 trials. The biomarkers included neurotrophic factors, inflammatory factors, oxidative stress markers, neuropathological hallmarks, metabolic biomarkers and genotypes. The meta-analyses indicated that exercise significantly decreased the levels of IL-6 (SMD = -0.45; 95% CI: -0.72, -0.18) and low-density lipoprotein (SMD = -0.26; 95% CI: -0.50, -0.01). Subgroup analyses showed that aerobic exercise also could decrease the levels of TNF-α (SMD = -1.21; 95% CI: -2.29, -0.14). There were some important cognition-related biomarkers which were rarely measured, such as Aβ, tau and IGF-1.

CONCLUSION

Regular exercise showed positive effects on reducing inflammation and regulating lipid metabolism. But the available evidence is limited and more studies with different exercise interventions should be conducted to test the effects of exercise on other important cognition-related biomarkers in patients with cognitive dysfunction.

Associations Between Physical Activity, Blood-Based Biomarkers of Neurodegeneration, and Cognition in Healthy Older Adults: The MAPT Study

Physical activity (PA) demonstrated benefits on brain health, but its relationship with blood biomarkers of neurodegeneration remains poorly investigated. We explored the cross-sectional associations of PA with blood concentrations of neurofilament light chain (NFL) and beta amyloid (Aβ)42/40. We further examined whether the interaction between PA and these biomarkers was longitudinally related to cognition. Four-hundred and sixty-five nondemented older adults engaged in an interventional study and who had a concomitant assessment of PA levels and blood measurements of NFL (pg/mL) and Aβ 42/40 were analyzed. A composite Z-score combining 4 cognitive tests was used for cognitive assessment up to a 4-year follow-up. Multiple linear regressions demonstrated that people achieving 500-999 and 2000+ MET-min/week of PA had lower (ln)NFL concentrations than their inactive peers. Logistic regressions revealed that achieving at least 90 MET-min/week of PA was associated with a lower probability of having high NFL concentrations (ie, ≥91.961 pg/mL [third quartile]). PA was not associated with (Aβ)42/40. Mixed-model linear regressions demonstrated that the reverse relationship between PA and cognitive decline tended to be more pronounced as Aβ 42/40 increased, while it was dampened with increasing levels of (ln)NFL concentrations. This study demonstrates that PA is associated with blood NFL but not with Aβ 42/40. Furthermore, it suggests that PA may attenuate the negative association between amyloid load and cognition, while having high NFL levels mitigates the favorable relationship between PA and cognition. More investigations on non demented older adults are required for further validation of the present findings.

Effects of Exercise Training Interventions on Executive Function in Older Adults: A Systematic Review and Meta-Analysis

Background

Chronic exercise training has been shown be to positively associated with executive function (EF) in older adults. However, whether the exercise training effect on EF is affected by moderators including the specific sub-domain of EF, exercise prescription variables, and sample characteristics remains unknown.

Objectives

This systematic and meta-analytic review of randomized controlled trials (RCTs) investigated the effects of exercise training on EF in older adults and explored potential moderators underlying the effects of exercise training on EF.

Methods

In accordance with the PRISMA guidelines, the electronic databases MEDLINE (PubMed) and EMBASE (Scopus) were searched from January 2003 to November 2019. All studies identified for inclusion were peer-reviewed and published in English. To be included, studies had to report findings from older (> 55 years old), cognitively normal adults or adults with mild cognitive impairment (MCI) randomized to an exercise training or a control group. The risk of bias in each study was appraised using the Cochrane risk-of-bias tool. Fixed-effects models were used to compare the effects of exercise training and control conditions on EF assessed at baseline and post-intervention. In addition, subgroup analyses were performed for three moderators (i.e., the specific sub-domain of EF, exercise prescription variables, and sample characteristics).

Results

Thirty-three RCTs were included. Overall, exercise training was associated with a significant small improvement in EF [Q(106) = 260.09, Hedges’ g = 0.21; p < 0.01]. The EF sub-domain moderator was not significant [Q(2) = 4.33, p > 0.05], showing that the EF improvement in response to exercise is evident for measures of inhibition, updating, and shifting. Regarding exercise prescription variables, results were significantly moderated by frequency of exercise training [Q(1) = 10.86, p < 0.05], revealing that effect sizes (ESs) were larger for moderate frequency (g = 0.31) as compared to low frequency exercise (g = 0.15). The results also showed type of exercise training moderated the ESs [Q(4) = 26.18, p < 0.05], revealing that ESs were largest for other forms of exercise (g = 0.44), followed by Tai Chi and yoga (g = 0.38), resistance exercise (g = 0.22), aerobic exercise (g = 0.14), and combined exercise (g = 0.10). In addition, The results showed moderated length of training the ESs [Q(2) = 16.64, p < 0.05], revealing that ESs were largest for short length (g = 0.32), followed by mid length (g = 0.26) and long length (g = 0.09). No significant difference in effects was observed as a function of exercise intensity [Q(1) = 2.87 p > 0.05] and session time [Q(2) = 0.21, p > 0.05]. Regarding sample characteristics, the results were significantly moderated by age [Q(2) = 20.64, p < 0.05], with significant benefits for young-old (55–65 years old) (g = 0.30) and mid-old (66–75 years old) (g = 0.25), but no effect on EF for old-old (more than 75 years old). The results were also significantly moderated by physical fitness levels [Q(1) = 10.80, p < 0.05], revealing that ESs were larger for sedentary participants (g = 0.33) as compared to physically fit participants (g = 0.16). In addition, results were also significantly moderated by cognitive status [Q(1) = 11.44, p < 0.05], revealing that ESs were larger for participants with cognitively normal (g = 0.26) as compared to those with mild cognitive impairment (g = 0.08). No significant differences in effects were observed as a function of sex [Q(2) = 5.38, p > 0.05].

Conclusions

Exercise training showed a small beneficial effect on EF in older adults and the magnitude of the effect was different across some moderators.

Physical Therapy for Gait, Balance, and Cognition in Individuals with Cognitive Impairment: A Retrospective Analysis

Objectives

The purpose of this study was to determine if a pragmatic physical therapy (PT) program was associated with improved cognition, gait, and balance in individuals with cognitive impairment. This study investigated these associations for individuals with Alzheimer disease (AD), vascular dementia (VaD), dementia with Lewy bodies (DLB), and mild cognitive impairment (MCI) in order to better characterize outcomes to PT for each diagnostic group.

Methods

Data before and after one month of physical therapy were extracted from patient records (67 with AD, 34 with VaD, 35 with DLB, and 37 with MCI). The mean number of PT sessions over a month was 3.4 (±1.8). Outcomes covered the domains of gait, balance, and cognition with multiple outcomes used to measure different constructs within the balance and gait domains.

Results

All groups showed improvements in balance and at least one gait outcome measure. Those with MCI improved in every measure of gait and balance performance. Lastly, cognition as measured by Montreal Cognitive Assessment improved in individuals in the AD, VaD, and MCI groups.

Conclusion

While this retrospective analysis is not appropriate for causal inference, results of one month of physical therapy were associated with decreases in gait, balance, and cognitive impairment in individuals with AD, VaD, DLB<, and MCI. Clinical Implications. While physical therapy is not typically a primary treatment strategy for individuals with cognitive impairment, the results of this study are consistent with the literature that demonstrates improvement from physical therapy for other neurodegenerative diseases. Further clinical and research exploration for physical therapy as a primary treatment strategy in these populations is warranted.

Environmental Risk Factors for Early-Onset Alzheimer's Dementia and Frontotemporal Dementia: A Case-Control Study in Northern Italy

Background: Early-onset dementia (EOD) is defined as dementia with symptom onset before 65 years. The role of environmental risk factors in the etiology of EOD is still undefined. We aimed at assessing the role of environmental risk factors in EOD etiology, taking into account its different clinical types. Methods: Using a case-control study, we recruited all EOD cases referred to Modena hospitals from 2016 to 2019, while the referent population was drawn from cases' caregivers. We investigated residential history, occupational and environmental exposures to chemicals and lifestyle behaviors through a self-administered questionnaire. We computed the odds ratios of EOD risk (overall and restricting to the Alzheimer's dementia (AD) or frontotemporal dementia (FTD) diagnoses) and the corresponding 95% confidence intervals using an unconditional logistic regression model. Results: Fifty-eight EOD patients (19 FTD and 32 AD) and 54 controls agreed to participate. Most of the investigated exposures, such as occupational exposure to aluminum, pesticides, dyes, paints or thinners, were associated with an increased odds ratio (OR) for FTD but not for AD. Long-term use of selenium-containing dietary supplements was associated with increased OR for EOD and, particularly, for FTD. For both EOD forms, smoking and playing football showed an increased odds ratio, while cycling was associated with increased risk only in FTD. Overall sports practice appeared to be a protective factor for both types. Conclusions: Our results suggest a role of environmental and behavioral risk factors such as some chemical exposures and professional sports in EOD etiology, in particular with reference to FTD. Overall sports practice may be associated with a reduced EOD risk.

Modulation of MicroRNAs as a Potential Molecular Mechanism Involved in the Beneficial Actions of Physical Exercise in Alzheimer Disease

Alzheimer disease (AD) is one of the most common neurodegenerative diseases, affecting middle-aged and elderly individuals worldwide. AD pathophysiology involves the accumulation of beta-amyloid plaques and neurofibrillary tangles in the brain, along with chronic neuroinflammation and neurodegeneration. Physical exercise (PE) is a beneficial non-pharmacological strategy and has been described as an ally to combat cognitive decline in individuals with AD. However, the molecular mechanisms that govern the beneficial adaptations induced by PE in AD are not fully elucidated. MicroRNAs are small non-coding RNAs involved in the post-transcriptional regulation of gene expression, inhibiting or degrading their target mRNAs. MicroRNAs are involved in physiological processes that govern normal brain function and deregulated microRNA profiles are associated with the development and progression of AD. It is also known that PE changes microRNA expression profile in the circulation and in target tissues and organs. Thus, this review aimed to identify the role of deregulated microRNAs in the pathophysiology of AD and explore the possible role of the modulation of microRNAs as a molecular mechanism involved in the beneficial actions of PE in AD.

Role of nurses in addressing modifiable risk factors for early Alzheimer's disease and mild cognitive impairment

A multidisciplinary advisory group of health professionals involved in dementia care assessed the current evidence base regarding modifiable risk factors (MRFs) for early Alzheimer's disease and mild cognitive impairment. Based on evidence from the published literature and clinical experience, MRFs in four areas were identified where there is evidence to support interventions that may help delay cognitive decline or reduce the risk of developing Alzheimer's disease: medical (eg cardiovascular risk factors), psychosocial (eg depression, anxiety, social isolation), lifestyle (eg lack of physical activity, smoking) and nutrition (eg poor diet, lack of micronutrients). Practical guidance on how health professionals, but in particular nurses, may actively seek to address these MRFs in clinical practice was also developed. Nurses are at the forefront of patient care and, as such, are ideally placed to offer advice to patients that may proactively help mitigate the risks of cognitive decline and the development of Alzheimer's disease.

Exercise, diet and stress as modulators of gut microbiota: Implications for neurodegenerative diseases

The last decade has witnessed an exponentially growing interest in gut microbiota and the gut-brain axis in health and disease. Accumulating evidence from preclinical and clinical research indicate that gut microbiota, and their associated microbiomes, may influence pathogenic processes and thus the onset and progression of various diseases, including neurological and psychiatric disorders. In fact, gut dysbiosis (microbiota dysregulation) has been associated with a range of neurodegenerative diseases, including Alzheimer's, Parkinson's, Huntington's and motor neuron disease, as well as multiple sclerosis. The gut microbiota constitutes a dynamic microbial system constantly challenged by many biological variables, including environmental factors. Since the gut microbiota constitute a changeable and experience-dependent ecosystem, they provide potential therapeutic targets that can be modulated as new interventions for dysbiosis-related disorders, including neurodegenerative diseases. This article reviews the evidence for environmental modulation of gut microbiota and its relevance to brain disorders, exploring in particular the implications for neurodegenerative diseases. We will focus on three major environmental factors that are known to influence the onset and progression of those diseases, namely exercise, diet and stress. Further exploration of environmental modulation, acting via both peripheral (e.g. gut microbiota and associated metabolic dysfunction or 'metabolopathy') and central (e.g. direct effects on CNS neurons and glia) mechanisms, may lead to the development of novel therapeutic approaches, such as enviromimetics, for a wide range of neurological and psychiatric disorders.

Higher Cardiorespiratory Fitness Is Associated With Better Verbal Generativity in Community-Dwelling Older Adults

Objectives: To examine the associations between physical activity duration and intensity, cardiorespiratory fitness, and executive function in older adults. Methods: Data from 99 cognitively normal adults (age = 69.10 ± 5.1 years; n = 54 females) were used in the current study. Physical activity (intensity and duration) was measured with the International Physical Activity Questionnaire, and fitness was measured by analysis of maximal aerobic capacity, VO₂peak. Executive function was measured comprehensively, including measures of Shifting, Updating, Inhibition, Generativity, and Nonverbal Reasoning. Results: Higher levels of cardiorespiratory fitness were associated with better performance on Generativity (B = .55; 95% confidence interval [.15, .97]). No significant associations were found between self-reported physical activity intensity/duration and executive functions. Discussion: To our knowledge, this study is the first to identify an association between fitness and Generativity. Associations between physical activity duration and intensity and executive function requires further study, using objective physical activity measures and longitudinal observations.

Physical Exercise as Personalized Medicine for Dementia Prevention?

Accumulating evidence mainly from observational studies supports the notion that lifestyle factors such as regular physical activity can modulate potential risk factors of dementia. Regarding a potential mechanism for this interaction, results from intervention studies show that exercising can induce neuroplastic changes in the human brain. However, a detailed look at the study results reveals a wide interindividual variability in the observed effects. This heterogeneity may originate from the fact that there are “responders” and “non-responders” with respect to the impact of physical exercise on physiological outcome parameters (i.e., VO₂ peak) and the brain. From this, it follows that recommendations for physical exercise programs should not follow a “one size fits all” approach. Instead, we propose that the exercises should be tailored to an individual in order to maximize the potential neuroplastic and preventive effects of regular exercise. These adaptations should take the individual performance levels into account and impact both the quality (i.e., type) and the quantity of exercises (i.e., intensity, duration, and volume).

Association of non-exercise physical activity in mid- and late-life with cognitive trajectories and the impact of APOE ε4 genotype status: the Mayo Clinic Study of Aging

In this study derived from the population-based Mayo Clinic Study of Aging, we investigated whether non-exercise physical activity (PA) was associated with global and domain-specific cognitive trajectories (memory, language, visuospatial skills, attention) and whether the association differed by apolipoprotein E (APOE) ε4 genotype status. We included 2061 community-dwelling individuals aged ≥ 70 years (50.5% males, 26.7% APOE ε4 carriers) who were cognitively unimpaired at baseline and on whom serial cognitive data and self-reported information on non-exercise PA were available. We specifically inquired about non-exercise PA carried out at two time points, i.e., midlife (between 50 and 65 years of age) and late-life (within 1 year prior to assessment) and three intensity levels, i.e., light (e.g., laundry), moderate (e.g., scrubbing floors) and heavy (e.g., hard manual labor). Linear mixed-effect models revealed that engaging in midlife PA of moderate or heavy intensity was associated with significantly less-pronounced decline of z-scores in all cognitive domains. Similarly, participants that engaged in late-life moderate or heavy PA had less decline in visuospatial, attention and global z-scores than non-active peers. These associations varied depending on APOE ε4 carrier status, i.e., APOE ε4 non-carriers but not APOE ε4 carriers that engaged in late-life PA had less decline in cognitive z-scores. In contrast, engaging in midlife PA, irrespective of intensity, was significantly associated with less decline in memory function only among APOE ε4 carriers.

The role of repetitive transcranial magnetic stimulation (rTMS) in the treatment of cognitive impairment in patients with Alzheimer's disease: A systematic review and meta-analysis

BACKGROUND

Although repetitive transcranial magnetic stimulation (rTMS) has been considered a potentially effective treatment for cognitive impairment in patients with Alzheimer's disease (AD), previous studies have produced inconsistent results. The objective of this meta-analysis was to evaluate the effects of rTMS on cognitive function in patients with AD.

METHODS

PubMed, EMBASE, Web of Science, MEDLINE and Cochrane Central Register of Controlled Trials (CENTRAL) were searched for relevant terms. Abstracts of all papers were carefully reviewed, followed by data extraction, quality assessment, data synthesis and subgroup analyses.

RESULT

A total of 12 studies with 231 patients were included, with 8 randomized controlled studies and 4 self-controlled studies. Eleven studies used high frequency rTMS (≥ 5 Hz), but only one study directly compared the difference between low-frequency (1 Hz) and high-frequency (20 Hz). Random-effects analysis revealed that rTMS could significantly improve cognition compared with sham-rTMS (SMD: 0.60, 95% CI: 0.35-0.85, P < .0001). In subgroup analyses, the effect for stimulation at a single target was 0.13 (95% CI: -0.35-0.62) and multiple targets 0.86 (95% CI: 0.18-1.54). Treatment for ≤3 sessions produced an effect of 0.29 (95% CI: -1.04-1.62), whereas treatment for ≥5 sessions produced an effect of 2.77 (95% CI: 2.22-3.32). No differences were found for rTMS combined with medication or cognitive training.

CONCLUSIONS

rTMS can significantly improve cognitive ability in patients with mild to moderate AD. Stimulation of multiple sites and long-term treatment are better at improving AD-associated cognitive performance. Furthermore, some novel interventional targets, like precuneus (PC), may be a more effective therapeutic site to improve memory in AD.

Relationship between physical activity, cognition, and Alzheimer pathology in autosomal dominant Alzheimer's disease

INTRODUCTION

Little is known about effects of physical activity (PA) in genetically driven early-onset autosomal dominant Alzheimer's disease (AD).

METHODS

A total of 372 individuals participating at the Dominantly Inherited Alzheimer Network study were examined to evaluate the cross-sectional relationship of PA with cognitive performance, functional status, cognitive decline, and AD biomarkers in cerebrospinal fluid. Mutation carriers were categorized as high or low exercisers according to WHO recommendations.

RESULTS

Mutation carriers with high PA showed significantly better cognitive and functional performance and significantly less AD-like pathology in cerebrospinal fluid than individuals with low PA. Mutation carriers with high PA scored 3.4 points better on Mini Mental State Examination at expected symptom onset and fulfilled the diagnosis of very mild dementia 15.1 years later compared with low exercisers.

DISCUSSION

These results support a beneficial effect of PA on cognition and AD pathology even in individuals with genetically driven autosomal dominant AD.