Unraveling the mechanisms of NK cell dysfunction in aging and Alzheimer's disease: insights from GWAS and single-cell transcriptomics

Background

Aging is an important factor in the development of Alzheimer's disease (AD). The senescent cells can be recognized and removed by NK cells. However, NK cell function is gradually inactivated with age. Therefore, this study used senescence as an entry point to investigate how NK cells affect AD.

Methods

The study validated the correlation between cognition and aging through a prospective cohort of the National Health and Nutrition Examination Survey database. A cellular trajectory analysis of the aging population was performed using single-cell nuclear transcriptome sequencing data from patients with AD and different ages. The genome-wide association study (GWAS) cohort of AD patients was used as the outcome event, and the expression quantitative trait locus was used as an instrumental variable. Causal associations between genes and AD were analyzed by bidirectional Mendelian randomization (MR) and co-localization. Finally, clinical cohorts were constructed to validate the expression of key genes.

Results

A correlation between cognition and aging was demonstrated using 2,171 older adults over 60 years of age. Gene regulation analysis revealed that most of the highly active transcription factors were concentrated in the NK cell subpopulation of AD. NK cell trajectories were constructed for different age populations. MR and co-localization analyses revealed that CHD6 may be one of the factors influencing AD.

Conclusion

We explored different levels of AD and aging from population cohorts, single-cell data, and GWAS cohorts and found that there may be some correlations of NK cells between aging and AD. It also provides some basis for potential causation.

Neuron-derived extracellular vesicles in blood reveal effects of exercise in Alzheimer's disease

BACKGROUND

Neuron-derived extracellular vesicles (NDEVs) in blood may be used to derive biomarkers for the effects of exercise in Alzheimer's disease (AD). For this purpose, we studied changes in neuroprotective proteins proBDNF, BDNF, and humanin in plasma NDEVs from patients with mild to moderate AD participating in the randomized controlled trial (RCT) of exercise ADEX.

METHODS

proBDNF, BDNF, and humanin were quantified in NDEVs immunocaptured from the plasma of 95 ADEX participants, randomized into exercise and control groups, and collected at baseline and 16 weeks. Exploratorily, we also quantified NDEV levels of putative exerkines known to respond to exercise in peripheral tissues.

RESULTS

NDEV levels of proBDNF, BDNF, and humanin increased in the exercise group, especially in APOE ε4 carriers, but remained unchanged in the control group. Inter-correlations between NDEV biomarkers observed at baseline were maintained after exercise. NDEV levels of putative exerkines remained unchanged.

CONCLUSIONS

Findings suggest that the cognitive benefits of exercise could be mediated by the upregulation of neuroprotective factors in NDEVs. Additionally, our results indicate that AD subjects carrying APOE ε4 are more responsive to the neuroprotective effects of physical activity. Unchanged NDEV levels of putative exerkines after physical activity imply that exercise engages different pathways in neurons and peripheral tissues. Future studies should aim to expand upon the effects of exercise duration, intensity, and type in NDEVs from patients with early AD and additional neurodegenerative disorders.

TRIAL REGISTRATION

The Effect of Physical Exercise in Alzheimer Patients (ADEX) was registered in ClinicalTrials.gov on April 30, 2012 with the identifier NCT01681602.

Aerobic exercise does not affect serum neurofilament light in patients with mild Alzheimer's disease

Introduction

Aerobic exercise has been shown to modify Alzheimer pathology in animal models, and in patients with multiple sclerosis to reduce neurofilament light (NfL), a biomarker of neurodegeneration.

Objective

To investigate whether a 16-week aerobic exercise program was able to reduce serum NfL in patients with mild Alzheimer's disease (AD).

Methods

This is a secondary analysis of data from the multi-center Preserving Cognition, Quality of Life, Physical Health, and Functional Ability in Alzheimer's disease: The Effect of Physical Exercise (ADEX) study. Participants were randomized to 16 weeks of moderate intensity aerobic exercise or usual care. Clinical assessment and measurement of serum NfL was done at baseline and after the intervention.

Results

A total of 136 participants were included in the analysis. Groups were comparable at baseline except for APOEε4 carriership which was higher in the usual care group (75.3 versus 60.2%; p = 0.04). There was no effect of the intervention on serum NfL [intervention: baseline NfL (pg/mL) 25.76, change from baseline 0.87; usual care: baseline 27.09, change from baseline -1.16, p = 0.09].

Conclusion

The findings do not support an effect of the exercise intervention on a single measure of neurodegeneration in AD. Further studies are needed using other types and durations of exercise and other measures of neurodegeneration.

Clinical trial registration

clinicaltrials.gov, identifier NCT01681602.

Safety and efficacy of plasma transfusion from exercise-trained donors in patients with early Alzheimer's disease: protocol for the ExPlas study

INTRODUCTION

Given that exercise training reduces the risk of developing Alzheimer's disease (AD), induces changes in the blood composition and has widespread systemic benefits, it is reasonable to hypothesise that exercised plasma (ExPlas) may have rejuvenative properties. The main objective is to test safety and tolerability of transfusing ExPlas from young, healthy, fit adults to patients with mild cognitive impairment (MCI) or early AD. The study is a pilot for a future efficacy study. The key secondary objectives are examining the effect of plasma transfusions on cognitive function, fitness level, vascular risk profile, assessment of cerebral blood flow and hippocampal volume, quality of life, functional connectivity assessed by resting state functional MRI and biomarkers in blood and cerebrospinal fluid.

METHODS AND ANALYSIS

ExPlas is a double-blinded, randomised controlled clinical single-centre trial. Patients up to 75 years of age with diagnosis early symptomatic phase AD will be recruited from two Norwegian hospitals. ExPlas is plasma drawn by plasmapheresis once a month for 4 months, from a total of 30 fit male donors (aged 18-40, BMI≤27 kg/m² and maximal oxygen uptake>55 mL/kg/min). All units will be virus inactivated by the Intercept method in accordance with procedures at St. Olavs University Hospital. Comparison with isotonic saline allows differentiation from a non-blood product. The main study consists of 6 rounds of examinations in addition to 12 plasma transfusions divided over three 4-week periods during study year-1. It is also planned to conduct follow-up examinations 2 and 5 years after baseline ETHICS AND DISSEMINATION: Written informed consent will be obtained from all participants and participation is voluntary. All participants have a next of kin who will follow them throughout the study to represent the patient's interest. The study is approved by the Regional Committee for Medical and Health Research Ethics (REK 2018/702) and the Norwegian Medicines Agency (EudraCT No. 2018-000148-24). The study will be published in an open access journal and results will be presented at numerous national and international meetings as well as on social media platforms.

TRIAL REGISTRATION NUMBER

EudraCT No. 2018-000148-24.

CLINICALTRIALS

gov, NCT05068830.

Multimodal Preventive Trial for Alzheimer's Disease: MIND-ADmini Pilot Trial Study Design and Progress

Background

Interventions simultaneously targeting multiple risk factors and mechanisms are most likely to be effective in preventing cognitive impairment. This was indicated in the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) testing a multidomain lifestyle intervention among at-risk individuals. The importance of medical food at the early symptomatic disease stage, prodromal Alzheimer’s disease (AD), was emphasized in the LipiDiDiet trial. The feasibility and effects of multimodal interventions in prodromal AD are unclear.

Objectives

To evaluate the feasibility of an adapted FINGER-based multimodal lifestyle intervention, with or without medical food, among individuals with prodromal AD.

Methods

MIND-ADmini is a multinational proof-of-concept 6-month randomized controlled trial (RCT), with four trial sites (Sweden, Finland, Germany, France). The trial targeted individuals with prodromal AD defined using the International Working Group-1 criteria, and with vascular or lifestyle-related risk factors. The parallel-group RCT includes three arms: 1) multimodal lifestyle intervention (nutritional guidance, exercise, cognitive training, vascular/metabolic risk management and social stimulation); 2) multimodal lifestyle intervention+medical food (Fortasyn Connect); and 3) regular health advice/ care (control group). Primary outcomes are feasibility and adherence. Secondary outcomes are adherence to the individual intervention domains and healthy lifestyle changes.

Results

Screening began on 28 September 2017 and was completed on 21 May 2019. Altogether 93 participants were randomized and enrolled. The intervention proceeded as planned.

Conclusions

For the first time, this pilot trial tests the feasibility and adherence to a multimodal lifestyle intervention, alone or combined with medical food, among individuals with prodromal AD. It can serve as a model for combination therapy trials (non-pharma, nutrition-based and/or pharmacological interventions).

Effect of exercise on cognitive impairment in patients undergoing haemodialyses: A systematic review and meta-analysis of randomised controlled trials

BACKGROUND

The influence of exercise on cognition in patients undergoing haemodialysis has been examined. However, evidence elucidating the effects in this patient group is scarce.

OBJECTIVE

To examine the effect of exercise on cognitive impairment in patients undergoing haemodialysis and provide insight into the effects of various characteristics of exercise on cognitive impairment in this population.

DESIGN

A systematic review and meta-analysis, following the guidance of PRISMA was undertaken.

PARTICIPANTS

Adult patients undergoing haemodialysis.

RESULTS

This review found that exercise significantly improved cognitive impairment in patients undergoing haemodialysis (SMD = 0.37, 95% CI: 0.13, 0.60, p = 0.002). Subgroup analyses demonstrated that both intradialytic exercise (SMD = 0.82, 95% CI: 0.37, 1.26, p < 0.001) and interdialytic exercise (SMD = 0.24, 95% CI: 0.01, 0.47, p = 0.038), exercise for 16 weeks or over (SMD = 0.33, 95% CI: 0.07, 0.58, p = 0.012), and lasting for more than 30 minutes (SMD = 0.52, 95% CI: 0.17, 0.86, p = 0.004) significantly alleviated cognitive impairment. The effect of exercise on cognitive impairment in patients less than 65 years of age (SMD = 0.39, 95% CI: 0.10, 0.68, p = 0.009) was significantly better than those over 65.

CONCLUSION

Exercise significantly improves cognitive impairment in patients undergoing haemodialysis. Both Intradialytic and interdialytic exercise of at least 30 minutes duration, 3 times weekly, and at least for 16 weeks may play a significant role in alleviating cognitive impairment in patients under 65 years of age.

Single-cell RNA sequencing reveals B cell-related molecular biomarkers for Alzheimer's disease

In recent years, biomarkers have been integrated into the diagnostic process and have become increasingly indispensable for obtaining knowledge of the neurodegenerative processes in Alzheimer's disease (AD). Peripheral blood mononuclear cells (PBMCs) in human blood have been reported to participate in a variety of neurodegenerative activities. Here, a single-cell RNA sequencing analysis of PBMCs from 4 AD patients (2 in the early stage, 2 in the late stage) and 2 normal controls was performed to explore the differential cell subpopulations in PBMCs of AD patients. A significant decrease in B cells was detected in the blood of AD patients. Furthermore, we further examined PBMCs from 43 AD patients and 41 normal subjects by fluorescence activated cell sorting (FACS), and combined with correlation analysis, we found that the reduction in B cells was closely correlated with the patients' Clinical Dementia Rating (CDR) scores. To confirm the role of B cells in AD progression, functional experiments were performed in early-stage AD mice in which fibrous plaques were beginning to appear; the results demonstrated that B cell depletion in the early stage of AD markedly accelerated and aggravated cognitive dysfunction and augmented the Aβ burden in AD mice. Importantly, the experiments revealed 18 genes that were specifically upregulated and 7 genes that were specifically downregulated in B cells as the disease progressed, and several of these genes exhibited close correlation with AD. These findings identified possible B cell-based AD severity, which are anticipated to be conducive to the clinical identification of AD progression.

The role of physical and cognitive function in performance of activities of daily living in patients with mild-to-moderate Alzheimer's disease - a cross-sectional study

BACKGROUND

Several factors may play a role in the ability of patients with Alzheimer's disease to perform activities of daily living (ADL). The aim of this study was to examine the impact of different aspects of physical performance and cognitive functions on ADL in patients suffering from mild-to-moderate Alzheimer's disease.

METHODS

We conducted secondary analyses on cross-sectional baseline data from the randomized controlled multicentre study "Preserving quality of life, physical health and functional ability in Alzheimer's Disease: The effect of physical exercise" (ADEX). In total, 185 AD patients (76 women and 109 men), with a mean age on 70,4 years, were included. Data from physical performance tests (Astrand cycle test, Timed up & Go (TUG), Sit to Stand test (STS)) and cognitive tests (Mini Mental Status Examination (MMSE), Symbol Digit Modalities Test (SDMT), Stroop Color and Word test (Stroop)) were used. Their associations with ADL, measured on the ADCS-ADL scale was assessed in multivariable regression analyses.

RESULTS

SDMT and MMSE had significant, moderate correlations with total ADL (SDMT: r = 0.33, MMSE: r = 0.42) and instrumental ADL (SDMT: r = 0.31, MMSE: r = 0.42), but not with basic ADL. Adjusting for age and sex, the associations between SDMT and MMSE to total ADL and instrumental ADL persisted. No significant associations were found between Astrand, TUG, STS or Stroop and total ADL, basic ADL or instrumental ADL.

CONCLUSION

Total ADL and instrumental ADL are associated with cognitive functions, including executive function. No significant association between examined physical performance parameters and ADL functions was observed, and consequently does not support an impact of physical function on ADL functions in patients with mild-to-moderate Alzheimer's disease and relatively well-preserved physical function. Strategies aimed to improve cognition may be better suited to improve ADL function in patients with mild-to-moderate Alzheimer's disease.

TRIAL REGISTRATION

NCT01681602 . Registered 10 September 2012, retrospectively registered.

Physical Exercise May Increase Plasma Concentration of High-Density Lipoprotein-Cholesterol in Patients With Alzheimer's Disease

Lifestyle factors have been shown to increase the risk of developing Alzheimer's disease (AD) later in life. Specifically, an unfavorable cholesterol profile, and insulin resistance are associated with increased risk of developing AD. One way to non-pharmacologically affect the levels of plasma lipids is by exercise, which has been shown to be beneficial in cognitively healthy individuals. In this randomized controlled trial y, we therefore aimed to clarify the effect of physical exercise on the lipid profile, insulin and glucose in patients with AD. In addition, we investigated the effect of apolipoproteinE genotype on total cholesterol, high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), and triglycerides (TG) in plasma from patients with AD. Plasma samples from 172 patients who underwent 16 weeks of moderate-to-high intensity exercise (n = 90) or treatment as usual (n = 82) were analyzed change from baseline for the levels of total cholesterol, LDL-C, HDL-C, TG, glucose, and insulin. In addition, we analyzed those from the exercise group who adhered to the protocol with an attendance of 2/3 or more of the exercise session and who followed the protocol of an intensity of 70% of the maximum heart rate. We found a significant increase in plasma HDL-C levels between the "high exercise sub-group" compared to control group. After intervention HDL-C was increased by 4.3% in the high-exercise group, and decreased by 0.7% in the control group, after adjustment for statin use. In conclusion, short term physical activity may be beneficial on the cholesterol profile in patients with AD.

Change in Fitness and the Relation to Change in Cognition and Neuropsychiatric Symptoms After Aerobic Exercise in Patients with Mild Alzheimer's Disease

BACKGROUND

Physical activity has the potential to improve physical function in patients with Alzheimer's disease (AD) and may contribute to modify disease processes and cognitive function.

OBJECTIVE

The aim of this study was to investigate 1) the effect of moderate-high-intensity aerobic exercise on cardiorespiratory fitness, i.e., peak oxygen uptake (VO2peak) determined by direct breath-by-breath cardiopulmonary exercise test, and 2) the association between changes in VO2peak and changes in cognition and neuropsychiatric symptoms in patients with mild AD.

METHODS

The study is based on secondary outcome analyses from the large single-blinded multi-center study ADEX (Preserving Cognition, Quality of Life, Physical Health and Functional Ability in Alzheimer's Disease: The Effect of Physical Exercise). A preselected sub-group of 55 participants (age 52-83 years), 29 from the intervention group (IG) and 26 from the control group (CG), was included. IG performed 16 weeks of supervised moderate-to-high intensity aerobic exercise. Assessments of VO2peak, mental speed and attention (Symbol Digit Modalities Test, SDMT), and neuropsychiatric symptoms (Neuropsychiatric Inventory, NPI) were performed at baseline and at 16 weeks.

RESULT

VO2peak increased 13% in the IG and a between-group difference in mean change (3.92 ml/kg/min, 95% CI 6.34-1.51, p = 0.003) was present in favor of the IG. Combined data from IG and CG showed positive associations between changes in VO2peak and changes in NPI (Rho = - 0.41, p = 0.042) and changes in SDMT (Rho = 0.36, p = 0.010), respectively.

CONCLUSION

Aerobic exercise improves VO2peak in community-dwelling patients with mild AD. Furthermore, changes in VO2peak appear to be associated to changes in cognition and neuropsychiatric symptoms.

Effects of physical activity and exercise on the cognitive function of patients with Alzheimer disease: a meta-analysis

BACKGROUND

Alzheimer's disease (AD), as the most common cause of dementia, brings huge economic burden for patients and social health care systems, which motivates researchers to study multiple protective factors, among which physical activity and exercise have been proven to be both effective and economically feasible.

METHODS

A systematic literature search was performed for eligible studies published up to November 1st 2018 on three international databases (PubMed, Cochrane Library, and Embase) and two Chinese databases (Wanfang Data, China National Knowledge Infrastructure). All analyses were conducted using Stata 14.0. Due to heterogeneity between studies, a random-effects model was used for this meta-analysis. Meta-analysis was used to explore if physical activity and exercise can exert positive effects on cognition of elderly with AD and subgroup analyses were conducted to find out if there are dose-response effects.

RESULTS

A total of 13 randomized controlled trials were included with a sample size of 673 subjects diagnosed with AD. Intervention groups showed a statistically significant improvement in cognition of included subjects measured by the MMSE score (SMD = 1.12 CI:0.66~1.59) compared to the control groups. Subgroup analyses showed different amounts of physical activity and exercise can generate different effects.

CONCLUSIONS

As one of few meta-analyses comparing different quantities of physical activity and exercise interventions for AD in details, our study suggests that physical activity and exercise can improve cognition of older adults with AD. While the concomitant effects on cognition functions of high frequency interventions was not greater than that of low frequency interventions, the threshold remains to be settled. However, more RCTs with rigorous study design are needed to support our findings.

Moderate- to high-intensity exercise does not modify cortical β-amyloid in Alzheimer's disease

INTRODUCTION

Animal models of Alzheimer's disease show that exercise may modify β-amyloid (Aβ) deposition. We examined the effect of a 16-week exercise intervention on cortical Aβ in patients with mild-to-moderate Alzheimer's disease.

METHODS

Thirty-six patients with Alzheimer's disease were randomized to either one hour of aerobic exercise three times weekly for 16 weeks or usual care. Pre and post intervention, 11Carbon-Pittsburgh compound B positron emission tomography was carried out to assess cortical Aβ, and quantified using standardized uptake value rations (SUVRs).

RESULTS

The intervention showed no effect on follow-up SUVRs in a covariance analysis with group allocation, baseline intervention SUVR, age, sex, and baseline Mini-Mental State Examination as predictors. Change in SUVRs did not correlate with changes in measures of physical or aerobic fitness.

DISCUSSION

The present findings do not support an effect of exercise on Aβ. However, the relatively short intervention period may account for a lack of efficacy. Further studies should test earlier and longer interventions.

Exercise as a potential modulator of inflammation in patients with Alzheimer's disease measured in cerebrospinal fluid and plasma

BACKGROUND

Neuroinflammation is recognized as part of the pathological progression of Alzheimer's disease (AD), but the molecular mechanisms are still not entirely clear. Systemically, physical exercise has shown to have a positive modulating effect on markers of inflammation. It is not known if this general effect also takes place in the central nervous system in AD. The aim of this study was to investigate the effect of 16 weeks of moderate to high-intensity physical exercise on selected biomarkers of inflammation both systemically and in the CNS, in patients with AD.

METHODS

Plasma and cerebrospinal fluid (CSF) from 198 patients with Alzheimer's disease participating in the Preserving Cognition, Quality of Life, Physical Health and Functional Ability in Alzheimer's Disease: The Effect of Physical Exercise (ADEX) study were analyzed for concentrations of 8‑isoprostane, soluble trigger receptor expressed on myeloid cells 2 (sTREM2), and the MSD v-plex proinflammation panel 1 human containing interferon gamma (IFNγ), Interleukin-10 (IL10), IL12p70, IL13, IL1β, IL2, IL4, IL6, IL8, and tumor necrosis factor alpha (TNFα), before and after a 16-week intervention with physical exercise, and we studied whether changes were modulated by the patients' APOE genotype.

RESULTS

Most inflammatory markers remained unchanged after exercise. We found an increasing effect of 16 weeks of physical exercise on sTREM2 measured in CSF. Further, IL6 in plasma increased in the exercise group after physical exercise (mean relative change 41.03, SD 76.7), compared to controls (-0.97, SD 49.4). In a sub-analysis according to APOE genotype, we found that in ε4 carriers, exercise had a stabilizing effect on IFNγ concentration with a mean relative change of 7.84 (SD 42.6), as compared to controls (114.7 (SD 188.3), p = 0.038.

CONCLUSION

Our findings indicate an effect of physical exercise on markers of neuroinflammation in CSF measured by an increase in sTREM2 in patients with AD. Further, there may be a small inflammatory systemic effect related to physical exercise in patients with AD.

Patients with Alzheimer's disease who carry the APOE ε4 allele benefit more from physical exercise

Introduction

Our group has completed an exercise study of 200 patients with mild Alzheimer's disease. We found improvements in cognitive, neuropsychiatric, and physical measures in the participants who adhered to the protocol. Epidemiological studies in healthy elderly suggest that exercise preserves cognitive and physical abilities to a higher extent in APOE ε4 carriers.

Methods

In this post hoc subgroup analysis study, we investigated whether the beneficial effect of an exercise intervention in patients with mild AD was dependent on the patients' APOE genotype.

Results

We found that patients who were APOE ε4 carriers benefitted more from the exercise intervention by preservation of cognitive performance and improvement in physical measures.

Discussion

This exploratory study establishes a possible connection between the beneficial effects of exercise in AD and the patients' APOE genotype. These findings, if validated, could greatly impact the clinical management of patients with AD and those at risk for developing AD.

A 16-Week Aerobic Exercise Intervention Does Not Affect Hippocampal Volume and Cortical Thickness in Mild to Moderate Alzheimer's Disease

Introduction: Brain imaging studies in healthy elderly subjects suggest a positive effect of aerobic exercise on both brain structure and function, while the effects of aerobic exercise in Alzheimer’s Disease (AD) has been scarcely investigated.

Methods: In a single-blinded randomized MRI study, we assessed the effects of an aerobic exercise intervention on brain volume as measured by magnetic resonance imaging (MRI) and its correlation to cognitive functioning in patients with AD. The study was a sub-study of a larger randomized controlled trial (ADEX study). Forty-one patients were assigned to a control or exercise group. The exercise group performed 60-min of aerobic exercise three times per week for 16 weeks. All participants underwent whole-brain MRI at 3 Tesla and cognitive assessment at baseline and after 16 weeks. Attendance and intensity were monitored providing a total exercise load. Changes in regional brain volumes and cortical thickness were analyzed using Freesurfer software.

Results: There was no effect of the type of intervention on MRI-derived brain volumes. In the entire group with and without training, Exercise load showed a positive correlation with changes in volume in the hippocampus, as well as frontal cortical thickness. Volume changes in frontal cortical thickness correlated with changes in measures of mental speed and attention and exercise load in the exercise group.

Conclusion: We did not find evidence to support an effect of 16 weeks of aerobic exercise on brain volume changes in patients with AD. Longer intervention periods may be needed to affect brain structure as measured with volumetric MRI.

Clinical Trial registration:ClinicalTrials.gov Identifier: NCT01681602, registered September 10th, 2012 (Retrospectively registered).

The effect of physical exercise on cerebral blood flow in Alzheimer's disease

In recent years there has been an increasing focus on the relation between cerebrovascular health, physical exercise and Alzheimer's disease. The aim of the current study was to determine the effect of moderate-to-high-intensity aerobic exercise on cerebral blood flow in patients with mild to moderate Alzheimer's disease. Fifty-one patients were randomized to either usual care or moderate-to-high intensity aerobic exercise for 16 weeks. Exercise had no consistent effect on whole brain or regional cerebral blood flow. Sixteen weeks of exercise are, therefore, not sufficient to produce a consistent increase in cerebral blood flow in a relatively small sample of Alzheimer's patients.

Technology-Based Behavioral Interventions for Daily Activities and Supported Ambulation in People With Alzheimer's Disease

OBJECTIVES

These 2 studies evaluated technology-based behavioral interventions for promoting daily activities and supported ambulation in people with mild-to-moderate and moderate-to-severe Alzheimer's disease, respectively.

METHODS

Study 1 included 8 participants who were taught to start and carry out daily activities on their own using a tablet or smartphone device, which provided activity reminders, step instructions, and praise. Study 2 included 9 participants who were taught to engage in brief periods of ambulation using a walker combined with a tilt microswitch and a notebook computer, which monitored step responses and provided stimulation and prompts.

RESULTS

The participants of study 1 succeeded in starting the activities independently and carrying them out accurately. The participants of study 2 largely increased their ambulation levels and also showed signs of positive involvement (eg, smiles and verbalizations).

CONCLUSION

The aforementioned technology-based interventions may represent practical means for supporting people with Alzheimer's disease.

Cerebrospinal Fluid Amyloid Beta and Tau Concentrations Are Not Modulated by 16 Weeks of Moderate- to High-Intensity Physical Exercise in Patients with Alzheimer Disease

BACKGROUND

Physical exercise may have some effect on cognition in patients with Alzheimer disease (AD). However, the underlying biochemical effects are unclear. Animal studies have shown that amyloid beta (Aβ), one of the pathological hallmarks of AD, can be altered with high levels of physical activity.

AIM

The objective of this study was to elucidate the effect of 16 weeks of moderate- to high-intensity physical exercise on the biomarkers of AD, with special emphasis on the amyloidogenic pathway.

METHODS

From a total of 53 patients with AD participating in the Preserving Cognition, Quality of Life, Physical Health and Functional Ability in Alzheimer's Disease: The Effect of Physical Exercise (ADEX) study we analyzed cerebrospinal fluid samples for Aβ species, total tau (t-tau), phosphorylated tau (p-tau) and soluble amyloid precursor protein (sAPP) species. We also assessed the patients for apolipoprotein E ε4 (ApoE ε4) genotype.

RESULTS

We found no effect of 16 weeks of physical exercise on the selected biomarkers, and no effect of ApoE ε4 genotype.

CONCLUSION

Our findings suggest that the possible effect of physical exercise on cognition in patients with AD is not due to modulation of Aβ, t-tau, p-tau and sAPP species.

A technology-aided program for helping persons with Alzheimer’s disease perform daily activities

Purpose

Persons with mild and moderate Alzheimer’s disease experience increasing activity engagement failures, with consequent cognitive, social, and physical drawbacks. The purpose of this paper is to assess a technology-aided program to help these persons to independently start and carry out daily activities at the appropriate times.

Design/methodology/approach

The program was implemented with eight participants according to an adapted non-concurrent multiple baseline design across participants. The program provided each participant with: timely reminders about the activities to carry out, verbal instructions about the activity steps, and brief encouragements and praise.

Findings

All participants showed improvement during the program, that is, they managed to independently start the activities at the scheduled times and perform those activities with satisfactory levels of accuracy (i.e. with mean percentages of correct steps nearing or exceeding 90).

Originality/value

A technology-aided program, such as that used in this study, may help persons with mild and moderate Alzheimer disease engage in daily activities, with possible benefits for their cognitive functioning, social image, and physical condition.

Cost-effectiveness of a randomised trial of physical activity in Alzheimer's disease: a secondary analysis exploring patient and proxy-reported health-related quality of life measures in Denmark

OBJECTIVES

To explore the cost-effectiveness of a supervised moderate-to-high intensity aerobic exercise programme in people diagnosed with Alzheimer's disease (AD) and estimate incremental cost-effectiveness ratios (ICER) using participant-reported and proxy-reported measures of health-related quality of life (HRQoL) DESIGN: A cost-effectiveness analysis of economic and HRQoL data from a randomised trial delivered over 16 weeks.

SETTING

Memory clinics in Denmark.

PARTICIPANTS

200 individuals with mild AD aged 50-90 years gave informed consent to participate in the study. Participants were randomised to control or intervention group.

INTERVENTIONS

Control group received treatment as usual. The intervention group performed 1 hour of supervised moderate-to-high intensity aerobic exercise three times weekly for 16 weeks.

PRIMARY AND SECONDARY OUTCOMES MEASURES

Different physical, functional and health measures were obtained at inclusion (baseline) and 4 and 16 weeks after. HRQoL (EuroQol-5 Dimensions-5 Levels/EQ-Visual Analogue Scale) was reported by the participants and the primary caregivers as proxy respondents. Differences in HRQOL as reported by the participant and caregiver were explored as were different values of caregiver time with respite from care tasks.

RESULTS

The intervention cost was estimated at €608 and €496 per participant, with and without transport cost, respectively. Participants and caregivers in the intervention group reported a small, positive non-significant improvement in EQ-5D-5L and EQ-VAS after 16 weeks. The ICER was estimated at €72 000/quality-adjusted life year using participant-reported outcomes and €87000 using caregiver-reported outcomes.

CONCLUSIONS

The findings suggest that the exercise intervention is unlikely to be cost-effective within the commonly applied threshold values. The cost of the intervention might be offset by potential savings from reduction in use of health and social care.

TRIAL REGISTRATION NUMBER

https://clinicaltrials.gov/ct2/show/NCT01681602.

Supporting Simple Activity Engagement in Persons With Moderate to Severe Alzheimer's Disease Through a Technology-Aided Program

OBJECTIVES

These 2 studies assessed a technology-aided program to support mild physical exercise or simple occupational activity in participants with moderate to severe Alzheimer's disease.

METHODS

Study 1 included 11 participants who were to perform a leg-raising response. Study 2 included 10 participants who were to sort objects into different containers. The program ensured that they received positive stimulation contingent on the responses and reminders/prompts after periods of nonresponding. Each study was carried out according to a nonconcurrent multiple baseline design across participants.

RESULTS

The program was successful in supporting mild physical exercise and activity with objects in the 2 groups of participants, respectively. The participants also showed signs of positive involvement (eg, smiles and verbalizations) during the sessions. Moreover, staff personnel rated the program and its impact positively.

CONCLUSION

The program may be considered a practical resource for supporting positive engagement in persons with moderate to severe Alzheimer's disease.

Effect of physical exercise on markers of neuronal dysfunction in cerebrospinal fluid in patients with Alzheimer's disease

INTRODUCTION

Physical exercise has gained increasing focus as a potential mean to maintain cognitive function in patients with Alzheimer's disease (AD). Alongside the markers of specific AD pathology (amyloid β and tau), other pathologies such as neuronal damage and synaptic loss have been proposed as markers of the disease. Here, we study the effect of physical exercise on biomarkers of neuronal and synaptic integrity.

METHODS

Cerebrospinal fluid (CSF) from 51 AD subjects who participated in the randomized controlled trial Preserving Cognition, Quality of Life, Physical Health and Functional Ability in Alzheimer's Disease: The Effect of Physical Exercise (ADEX) was analyzed for the concentration of neurofilament light (NFL), neurogranin (Ng), visinin-like protein-1 (VILIP-1), and chitinase-3-like protein 1 (YKL-40). Participants were subjected to either 16 weeks of moderate- to high-intensity exercise (n = 25) or treatment as usual (control group, n = 26), and CSF was collected before and after intervention.

RESULTS

No significant differences in CSF concentrations of VILIP-1, YKL-40, NFL, and Ng were observed when comparing mean change from baseline between the exercise and control groups. Similarly, when classifying subjects based on their exercise levels, no significant changes were observed for the biomarkers in the control group compared with the high-exercise group (attending 80% of the exercise sessions with an intensity of 70% of maximum heart rate or above).

DISCUSSION

These results are not supportive of a modulatory effect of physical exercise on the selected biomarkers of neuronal and synaptic integrity in patients with AD.

Cognitive deficits in non-demented diabetic elderly appear independent of brain amyloidosis

BACKGROUND

To determine the effects of Type 2 diabetes (DM2) on levels of brain amyloidosis and cognition in a community-dwelling cohort of nondemented elderly individuals.

METHODS

33 subjects (16 DM2, 17 nondiabetic) were prospectively recruited. Subjects underwent a PET scan using the amyloid tracer, Pittsburgh Compound B, and a neuropsychological evaluation. Associations between DM2, brain amyloidosis, and cognition were assessed using multivariate regressions, adjusting for age and APOE4 status.

RESULTS

DM2 subjects had lower global cognitive function (p=0.018), as measured by the Repeatable Battery for the Assessment of Neuropsychological Status. There was no difference in brain amyloidosis between groups (p=0.25).

CONCLUSIONS

Community-dwelling, nondemented individuals with DM2 had greater cognitive deficits, which do not appear to be mediated by brain amyloidosis. Further studies exploring potential mediators of these cognitive deficits should be performed.

Associations between physical function, dual-task performance and cognition in patients with mild Alzheimer's disease

OBJECTIVE

Alzheimer's disease (AD) causes a gradual decline in cognition, limitations of dual-tasking and physical function leading to total dependence. Hence, information about the interaction between physical function, dual-task performance and cognition may lead to new treatment strategies with the purpose of preserving function and quality of life. The objective of this study was to investigate the associations between physical function, dual-task performance and cognition in community-dwelling patients with mild AD.

METHODS

Baseline results from 185 participants (50-90 years old) in the single blinded multicenter RCT 'ADEX' (Alzheimer's disease: the effect of physical exercise) were used. Assessments included tests of physical function: 400-m walk test, 10-m walk test, Timed Up and Go test and 30-s chair stand test; dual-task performance, i.e., 10-m walk while counting backwards from 50 or naming the months backwards; and cognition, i.e., Mini Mental State Examination, Symbol Digit Modalities Test, the Stroop Color and Word Test, and Lexical verbal fluency test.

RESULTS

Results in the 30-s chair stand test correlated significantly with all tests of cognition (r = .208-.242) while the other physical function tests only randomly correlated with tests of cognition. Results in the dual-task counting backwards correlated significantly with results in all tests of cognition (r = .259-.388), which accounted for 7%-15% of the variation indicating that a faster time to complete dual-task performance was associated with better cognitive performance.

CONCLUSION

The evidence of the associations between physical function, dual-task performance and cognition is important when creating new rehabilitation interventions to patients with mild AD.

Persons With Advanced Alzheimer’s Disease Engage in Mild Leg Exercise Supported by Technology-Aided Stimulation and Prompts

This study assessed whether nine persons with advanced Alzheimer’s disease would learn to engage in leg responses (exercise) with the support of a technology-aided program, which provided (a) preferred stimulation contingent on the leg responses and (b) verbal reminders/prompts in case of no responding. The study was conducted according to a non-concurrent multiple baseline design across participants and involved sessions of 5 min. During the baseline, the participants’ mean frequencies of leg responses ranged from zero to slightly above two per session. During the intervention, those frequencies ranged from nearly 10 to nearly 17 per session. The mean frequencies of prompts varied across participants from about two to more than seven per session. In addition to the increase in leg responses, participants showed an increase in signs of positive personal involvement (e.g., smiles and positive verbalizations) during the intervention sessions as compared with the baseline sessions. The applicability and potential benefits of the program in daily contexts are discussed.

Technology-Aided Programs to Support Positive Verbal and Physical Engagement in Persons with Moderate or Severe Alzheimer's Disease

Pilot studies using technology-aided programs to promote verbal reminiscence and mild physical activity (i.e., positive forms of engagement) in persons with moderate or severe Alzheimer's disease have provided promising results (Lancioni et al., 2015a,b). The present two studies were aimed at upgrading and/or extending the assessment of those programs. Specifically, Study 1 upgraded the program for verbal reminiscence and assessed it with eight new participants. The upgraded version automatically monitored the participants' verbal behavior during the sessions, in which photos and brief videos were used to foster verbal reminiscence. Monitoring allowed computer approval and reminders to be consistent with the participants' behavior. Study 2 extended the assessment of the program for promoting mild physical activity with 10 new participants for whom arm-raising responses were targeted. The results of Study 1 showed that the participants' mean percentages of intervals with verbal engagement/reminiscence were below 10 during baseline and control sessions and between above 50 and nearly 80 during the intervention. The results of Study 2 showed that the mean frequencies of arm-raising responses were about or below four and between about 10 and 19 per session during the baseline and the intervention, respectively. The general implications of the aforementioned results and the need for new research in the area were discussed.

The Ever-Changing Morphology of Hippocampal Granule Neurons in Physiology and Pathology

Newborn neurons are continuously added to the hippocampal dentate gyrus throughout adulthood. In this review, we analyze the maturational stages that newborn granule neurons go through, with a focus on their unique morphological features during each stage under both physiological and pathological circumstances. In addition, the influence of deleterious (such as schizophrenia, stress, Alzheimer's disease, seizures, stroke, inflammation, dietary deficiencies, or the consumption of drugs of abuse or toxic substances) and neuroprotective (physical exercise and environmental enrichment) stimuli on the maturation of these cells will be examined. Finally, the regulation of this process by proteins involved in neurodegenerative and neurological disorders such as Glycogen synthase kinase 3β, Disrupted in Schizophrenia 1 (DISC-1), Glucocorticoid receptor, pro-inflammatory mediators, Presenilin-1, Amyloid precursor protein, Cyclin-dependent kinase 5 (CDK5), among others, will be evaluated. Given the recently acquired relevance of the dendritic branch as a functional synaptic unit required for memory storage, a full understanding of the morphological alterations observed in newborn neurons may have important consequences for the prevention and treatment of the cognitive and affective alterations that evolve in conjunction with impaired adult hippocampal neurogenesis.

Exercise training for managing behavioral and psychological symptoms in people with dementia: A systematic review and meta-analysis

This systematic review and meta-analysis of randomized controlled trials assessed the effects of exercise on behavioral and psychological symptoms of dementia (BPSD, including depression) in people with dementia (PWD). Secondary outcomes for the effects of exercise were mortality and antipsychotic use. Twenty studies were included in this review (n=18 in the meta-analysis). Most studies used a multicomponent exercise training (n=13) as intervention; the control group was often a usual care (n=10) or a socially-active (n=8) group. Exercise did not reduce global levels of BPSD (n=4. Weighted mean difference -3.884; 95% CI -8.969-1.201; I(2)=69.4%). Exercise significantly reduced depression levels in PWD (n=7). Standardized mean difference -0.306; 95% CI -0.571 to -0.041; I(2)=46.8%); similar patterns were obtained in sensitivity analysis performed among studies with: institutionalized people (p=0.038), multicomponent training (p=0.056), social control group (p=0.08), and low risk of attrition bias (p=0.11). Exploratory analysis showed that the principal BPSD (other than depression) positively affected by exercise was aberrant motor behavior. Exercise had no effect on mortality. Data on antipsychotics were scarce. In conclusion, exercise reduces depression levels in PWD. Future studies should examine whether exercise reduces the use (and doses) of antipsychotics and other drugs often used to manage BPSD.

Downstream Consequences of Exercise Through the Action of BDNF

Physical exercise produces many beneficial responses in the brain, which affect cognitive function, blood flow, neurogenesis and resistance to injury. However, the exact mechanisms whereby exercise produces an induction in the brain are not well understood. A significant consequence is the induction of growth factors, such as Brain-derived Neurotrophic Factor (BDNF). Cognitive decline that occurs with aging, as well as progression of neurodegenerative diseases, are strongly correlated with decreases in BDNF. In this article, we discuss the properties of neurotrophins and the mechanisms that can account for the ability of exercise to promote brain plasticity through BDNF.

Biochemical Markers of Physical Exercise on Mild Cognitive Impairment and Dementia: Systematic Review and Perspectives

BACKGROUND

The cognitive effects of physical exercise in patients with dementia disorders or mild cognitive impairment have been examined in various studies; however the biochemical effects of exercise from intervention studies are largely unknown. The objective of this systematic review is to investigate the published results on biomarkers in physical exercise intervention studies in patients with MCI or dementia.

METHODS

The PubMed database was searched for studies from 1976 to February 2015. We included intervention studies investigating the effect of physical exercise activity on biomarkers in patients with MCI or dementia.

RESULTS

A total of eight studies were identified (n = 447 patients) evaluating exercise regimes with variable duration (single session-three sessions/week for 26 weeks) and intensity (light-resistance training-high-intensity aerobic exercise). Various biomarkers were measured before and after intervention. Seven of the eight studies found a significant effect on their selected biomarkers with a positive effect of exercise on brain-derived neurotrophic factor, cholesterol, testosterone, estradiol, dehydroepiadrosterone, and insulin in the intervention groups compared with controls.

CONCLUSION

Although few studies suggest a beneficial effect on selected biomarkers, we need more knowledge of the biochemical effect of physical exercise in dementia or MCI.

Interaction between therapeutic interventions for Alzheimer's disease and physiological Aβ clearance mechanisms

Most therapeutic agents are designed to target a molecule or pathway without consideration of the mechanisms involved in the physiological turnover or removal of that target. In light of this and in particular for Alzheimer’s disease, a number of therapeutic interventions are presently being developed/investigated which target the amyloid-β peptide (Aβ). However, the literature has not adequately considered which Aβ physiological clearance pathways are necessary and sufficient for the effective action of these therapeutics. In this review, we evaluate the therapeutic strategies targeting Aβ presently in clinical development, discuss the possible interaction of these treatments with pathways that under normal physiological conditions are responsible for the turnover of Aβ and highlight possible caveats. We consider immunization strategies primarily reliant on a peripheral sink mechanism of action, small molecules that are reliant on entry into the CNS and thus degradation pathways within the brain, as well as lifestyle interventions that affect vascular, parenchymal and peripheral degradation pathways. We propose that effective development of Alzheimer’s disease therapeutic strategies targeting Aβ peptide will require consideration of the age- and disease-specific changes to endogenous Aβ clearance mechanisms in order to elicit maximal efficacy.

Persons with Alzheimer's disease engage in leisure and mild physical activity with the support of technology-aided programs

Three studies were conducted to assess technology-aided programs to promote leisure engagement and mild physical activity in persons with Alzheimer's disease. Specifically, Study I assessed a program aimed at enabling three patients with mild or moderate Alzheimer's disease to choose among different music options and activate the preferred ones. Studies II and III were directed at patients in the low moderate or severe stages of the Alzheimer's disease who were no longer capable of ambulating and spent their time generally inactive, sitting in their wheelchairs. In particular, Study II used a program to help three patients exercise an arm-raising movement. Study III used a program to help three patients exercise a leg-foot movement. Each study was carried out according to a nonconcurrent multiple baseline design across patients. Results were very encouraging. The patients of Study I learned to choose and activate their preferred music pieces. The patients of Studies II and III enhanced their performance of the target movements and increased their indices of positive participation (e.g., smiles and verbalizations) during the sessions. The applicability of the programs in daily contexts and their implications for the patients involved are discussed.

Transient dynamics of Aβ contribute to toxicity in Alzheimer's disease

The aggregation and deposition of the amyloid-β peptide (Aβ) in the brain has been linked with neuronal death, which progresses in the diagnostic and pathological signs of Alzheimer’s disease (AD). The transition of an unstructured monomeric peptide into self-assembled and more structured aggregates is the crucial conversion from what appears to be a harmless polypeptide into a malignant form that causes synaptotoxicity and neuronal cell death. Despite efforts to identify the toxic form of Aβ, the development of effective treatments for AD is still limited by the highly transient and dynamic nature of interconverting forms of Aβ. The variability within the in vivo “pool” of different Aβ peptides is another complicating factor. Here we review the dynamical interplay between various components that influence the heterogeneous Aβ system, from intramolecular Aβ flexibility to intermolecular dynamics between various Aβ alloforms and external factors. The complex dynamics of Aβ contributes to the causative role of Aβ in the pathogenesis of AD.