Pathophysiologic relationship between Alzheimer's disease, cerebrovascular disease, and cardiovascular risk: A review and synthesis

Pomalidomide Ameliorates H₂O₂-Induced Oxidative Stress Injury and Cell Death in Rat Primary Cortical Neuronal Cultures by Inducing Anti-Oxidative and Anti-Apoptosis Effects

Due to its high oxygen demand and abundance of peroxidation-susceptible lipid cells, the brain is particularly vulnerable to oxidative stress. Induced by a redox state imbalance involving either excessive generation of reactive oxygen species (ROS) or dysfunction of the antioxidant system, oxidative stress plays a central role in a common pathophysiology that underpins neuronal cell death in acute neurological disorders epitomized by stroke and chronic ones such as Alzheimer’s disease. After cerebral ischemia, for example, inflammation bears a key responsibility in the development of permanent neurological damage. ROS are involved in the mechanism of post-ischemic inflammation. The activation of several inflammatory enzymes produces ROS, which subsequently suppress mitochondrial activity, leading to further tissue damage. Pomalidomide (POM) is a clinically available immunomodulatory and anti-inflammatory agent. Using H₂O₂-treated rat primary cortical neuronal cultures, we found POM displayed neuroprotective effects against oxidative stress and cell death that associated with changes in the nuclear factor erythroid derived 2/superoxide dismutase 2/catalase signaling pathway. POM also suppressed nuclear factor kappa-light-chain-enhancer (NF-κB) levels and significantly mitigated cortical neuronal apoptosis by regulating Bax, Cytochrome c and Poly (ADP-ribose) polymerase. In summary, POM exerted neuroprotective effects via its anti-oxidative and anti-inflammatory actions against H₂O₂-induced injury. POM consequently represents a potential therapeutic agent against brain damage and related disorders and warrants further evaluation.

The Neuro-Immuno-Senescence Integrative Model (NISIM) on the Negative Association Between Parasympathetic Activity and Cellular Senescence

There is evidence that accumulated senescent cells drive age-related pathologies, but the antecedents to the cellular stressors that induce senescence remain poorly understood. Previous research suggests that there is a relationship between shorter telomere length, an antecedent to cellular senescence, and psychological stress. Existing models do not sufficiently account for the specific pathways from which psychological stress regulation is converted into production of reactive oxygen species. We propose the neuro-immuno-senescence integrative model (NISIM) suggesting how vagally mediated heart rate variability (HRV) might be related to cellular senescence. Prefrontally modulated, and vagally mediated cortical influences on the autonomic nervous system, expressed as HRV, affects the immune system by adrenergic stimulation and cholinergic inhibition of cytokine production in macrophages and neutrophils. Previous findings indicate that low HRV is associated with increased production of the pro-inflammatory cytokines IL-6 and TNF-α. IL-6 and TNF-α can activate the NFκB pathway, increasing production of reactive oxygen species that can cause DNA damage. Vagally mediated HRV has been related to an individual's ability to regulate stress, and is lower in people with shorter telomeres. Based on these previous findings, the NISIM suggest that the main pathway from psychological stress to individual differences in oxidative telomere damage originates in the neuroanatomical components that modulate HRV, and culminates in the cytokine-induced activation of NFκB. Accumulated senescent cells in the brain is hypothesized to promote age-related neurodegenerative disease, and previous reports suggest an association between low HRV and onset of Alzheimer's and Parkinson's disease. Accumulating senescent cells in peripheral tissues secreting senescence-associated secretory phenotype factors can alter tissue structure and function which can induce cancer and promote tumor growth and metastasis in old age, and previous research suggested that ability to regulate psychological stress has a negative association with cancer onset. We therefore conclude that the NISIM can account for a large proportion of the individual differences in the psychological stress-related antecedents to cellular senescence, and suggest that it can be useful in providing a dynamic framework for understanding the pathways by which psychological stress induce pathologies in old age.

MRI load of cerebral microvascular lesions and neurodegeneration, cognitive decline, and dementia

Objective

To explore the differential associations of neurodegeneration and microvascular lesion load with cognitive decline and dementia in older people and the modifying effect of the APOE genotype on these associations.

Methods

A sample of 436 participants (age ≥ 60 years) was derived from the population-based Swedish National study on Aging and Care in Kungsholmen, Stockholm, and clinically examined at baseline (2001–2003) and 3 occasions during the 9-year follow-up. At baseline, we assessed microvascular lesion load using a summary score for MRI markers of lacunes, white matter hyperintensities (WMHs), and perivascular spaces and neurodegeneration load for markers of enlarged ventricles, smaller hippocampus, and smaller gray matter. We assessed cognitive function using the Mini-Mental State Examination (MMSE) test and diagnosed dementia following the Diagnostic and Statistical Manual of Mental Disorders, 4th edition criteria. We analyzed data using linear mixed-effects, mediation, and random-effects Cox models.

Results

During the follow-up, 46 participants were diagnosed with dementia. Per 1-point increase in microvascular lesion and neurodegeneration score (range 0–3) was associated with multiple adjusted β-coefficients of −0.35 (95% confidence interval, −0.51 to −0.20) and −0.44 (−0.56 to −0.32), respectively, for the MMSE score and multiple adjusted hazard ratios of 1.68 (1.12–2.51) and 2.35 (1.58–3.52), respectively, for dementia; carrying APOE ε4 reinforced the associations with MMSE decline. WMH volume changes during the follow-up mediated 66.9% and 12.7% of the total association of MMSE decline with the baseline microvascular score and neurodegeneration score, respectively.

Conclusions

Both cerebral microvascular lesion and neurodegeneration loads are strongly associated with cognitive decline and dementia. The cognitive decline due to microvascular lesions is exacerbated by APOE ε4 and is largely attributed to progression and development of microvascular lesions.

Non-Alzheimer's contributions to dementia and cognitive resilience in The 90+ Study

The diagnosis of Alzheimer's disease (AD) in the oldest-old is complicated by the increasing prevalence of age-related neurofibrillary tangles, plaques and non-AD pathologies such as cerebrovascular disease (CVD), hippocampal sclerosis (HS), aging-related tau astrogliopathy (ARTAG), as well as TDP-43 and Lewy pathology. The contribution of these non-AD pathologies to dementia and cognitive resilience is unclear. We assessed the level of AD neuropathologic change (ADNPC) and non-AD pathology in 185 participants enrolled in The 90+ Study with available cognitive assessments and brain tissue. Logistic regression models-adjusting for age, sex and education-determined the association between each pathology and dementia or between subgroups. 53% had dementia, primarily AD or mixed AD; 23% had cognitive impairment without dementia (CIND); 23% were not impaired. Both AD and non-AD pathology was prevalent. 100% had tangles, 81% had plaques, and both tangles and plaques associated with dementia. ARTAG distributed across limbic (70%), brainstem (39%) and cortical regions (24%). 49% had possible CVD and 26% had definite CVD, while HS was noted in 15%. Cortical ARTAG, CVD and HS were each associated with dementia, but limbic and brainstem ARTAGs were not. TDP-43 and Lewy pathologies were found in 36 and 17% and both associated with dementia. No pathology distinguished CIND and the not impaired. By NIA-AA criteria and dementia status, the cohort was subdivided into four groups: those with minimal ADNPC included the not dementia (ND) and Not AD dementia groups; and those with significant ADNPC included the Resilient without dementia and AD dementia groups. Compared to the ND group, the Not AD dementia group had more HS, cortical ARTAG, TDP-43, and Lewy pathology. Compared to the AD dementia group, the Resilient group had less CVD, no HS and less cortical ARTAG, TDP-43 and Lewy pathology. Our findings imply that reductions in non-AD pathologies including CVD contribute to cognitive resilience in the oldest-old.

Associations between recent and established ophthalmic conditions and risk of Alzheimer's disease

INTRODUCTION

Identifying ophthalmic diseases associated with increased risk of Alzheimer's disease (AD) may enable better screening and understanding of those at risk of AD.

METHODS

Diagnoses of glaucoma, age-related macular degeneration (AMD), and diabetic retinopathy (DR) were based on International Classification of Diseases, 9th revision, codes for 3877 participants from the Adult Changes in Thought study. The adjusted hazard ratio for developing probable or possible AD for recent (within 5 years) and established (>5 years) diagnoses were assessed.

RESULTS

Over 31,142 person-years of follow-up, 792 AD cases occurred. The recent and established hazard ratio were 1.46 (P = .01) and 0.87 (P = .19) for glaucoma, 1.20 (P = .12) and 1.50 (P < .001) for AMD, and 1.50 (P = .045) and 1.50 (P = .03) for DR.

DISCUSSION

Increased AD risk was found for recent glaucoma diagnoses, established AMD diagnoses, and both recent and established DR. People with certain ophthalmic conditions may have increased AD risk.

Helicobacter pylori and extragastric diseases: A review

Helicobacter pylori (H. pylori) infection is very common and affects approximately half of the world population. It causes gastric diseases, but some authors have reported an association of H. pylori infection with other systemic manifestations beginning in 1994. The list of potential effects of H. pylori outside the stomach includes a number of extragastric manifestations and we focused on neurological, dermatological, hematologic, ocular, cardiovascular, metabolic, allergic, and hepatobiliary diseases. This review discusses these important reported manifestations that are not related to the gastrointestinal tract.

The Protective Effects of Clams on Hypercholesterolemia in Late-Stage Triple-Transgenic Alzheimer's Diseased Mice Hearts

To investigate a high cholesterol diet in Alzheimer’s disease (AD) mice, they were fed with (2% cholesterol) in five groups with a control group, AD mice group, AD mice plus Meretrix lusoria group, AD mice plus Geloina eros group, and, AD mice plus Corbicula fluminea group for three months, and treated with the fatty acid profiles of clams by gas chromatography (GC). The results showed that treatment with clams for three months reduced Fas/L and Caspase-3 in the Meretrix lusoria and Geloina eros groups, but Fas-associated death domain (FADD) and Caspase-8 were strongly reduced in the Geloina eros group. For the mitochondria-dependent apoptotic pathway, the reduction of apoptosis proteins were observed in the hearts of clams-treated AD mice. BAK and Caspase-9 was reduced in the Meretrix lusoria group, but Caspase-3 and Cytochrome-c were reduced in Geloina eros group. Enhancement of survival proteins p-AKT, p-IGF1R, p-PI3K, Bcl-XL, Bcl2, and the longevity SIRT1 signaling proteins, p-AMPK-α, SIRT1, PGC1-α, p-FOXO3 were observed in clams-treated mice and even more strongly enhanced in the Meretrix lusoria, Geloina eros and Corbicula fluminea groups. This study observed that the ingestion of clams caused a reduction of apoptosis proteins and enhancement of survival and SIRT1 signaling proteins in the hearts.

Association of orthostatic hypotension with incident dementia, stroke, and cognitive decline

OBJECTIVE

To examine associations of orthostatic hypotension (OH) with dementia and long-term cognitive decline and to update previously published results in the same cohort for stroke with an additional 16 years of follow-up.

METHODS

We analyzed data from 11,709 participants without a history of coronary heart disease or stroke who attended the baseline examination (1987-1989) of the prospective Atherosclerosis Risk in Communities (ARIC) study. OH was defined as a drop in systolic blood pressure (BP) of at least 20 mm Hg or a drop in diastolic BP of at least 10 mm Hg on standing. Dementia was ascertained via examination, contact with participants or their proxy, or medical record surveillance. Ischemic stroke was ascertained via cohort surveillance of hospitalizations, cohort follow-up, and linkage with registries. Both outcomes were adjudicated. Cognitive function was ascertained via 3 neuropsychological tests administered in 1990 to 1992 and 1996 to 1998 and a full battery of tests in 2011 to 2013. Scores were summarized and reported as SDs. We used adjusted Cox regression and linear mixed models.

RESULTS

Over ≈25 years, 1,068 participants developed dementia and 842 had an ischemic stroke. Compared to persons without OH at baseline, those with OH had a higher risk of dementia (hazard ratio [HR] 1.54, 95% confidence interval [CI] 1.20-1.97) and ischemic stroke (HR 2.08, 95% CI 1.65-2.62). Persons with OH had greater, although nonsignificant, cognitive decline over 20 years (SD 0.09, 95% CI -0.02 to 0.21).

CONCLUSIONS

OH assessed in midlife was independently associated with incident dementia and ischemic stroke. Additional studies are needed to elucidate potential mechanisms for these associations and possible applications for prevention.

Dementia in 'super-aged' Japan: challenges and solutions

Japan, as a 'super-aged' society, is at the forefront of the socioeconomic change resulting from the unprecedented demographic shift of aging societies, and is an exemplar for other countries. Within neurodegenerative disorders, a deeper understanding of the issues faced by aging societies, and their ramifications on the mental well being and cognitive health of older adults, is important. Japan's pioneering approaches in assistive technology and 'gerontotechnology' have the potential to enhance the field of dementia in terms of assessment, diagnosis and care. This article is a narrative review of the issue of aging and dementia in Japan by discussing demographics, implications of a 'super-aged' society, challenges and potential solutions to the growing issue of dementia in the world's most aged nation.

Risk of Alzheimer's disease with metal concentrations in whole blood and urine: A case-control study using propensity score matching

Environmental exposure to heavy metals is suspected to result in neuropathology damage and cognitive impairment. We aimed to explore the association of Alzheimer's disease (AD) risk with the internal dose of heavy metals by constructing a hospital-based case-control study and using propensity-score-matching methods. We investigated 170 patients with AD and 264 controls from the Department of Neurology and Family Medicine, China Medical University Hospital in Taiwan. All patients with AD received clinical neuropsychological examination and cognitive-function assessments, including the mini-mental status examination and clinical dementia rating scale. We also constructed a propensity-score-matched population of 82 patients with AD and 82 controls by matching age, gender, education, and AD-related comorbidity. Blood levels with cadmium, lead, mercury, selenium, and urinary arsenic profile were measured. Logistic regression models and 95% confidence intervals (CIs) were applied to estimate AD risk. After stratification by respective quartile cutoffs of heavy metals, the AD risk of study participants with high urinary inorganic arsenic (InAs%) or low dimethylarsinic acid (DMA%) significantly increased (p < 0.05), as similarly found in the propensity-score-matched population. In addition, people with a low median level of selenium and high median level of InAs%, or/and a low median level of DMA% had approximately two- to threefold significant AD risk. Urinary arsenic profiles may be associated with increased AD risk. Repeat measurements of heavy metals with large sample size and the surveying of potential exposure sources are recommended in future studies.

Investigating the relationship between DNA methylation age acceleration and risk factors for Alzheimer's disease

Introduction

The “epigenetic clock” is a DNA methylation–based estimate of biological age and is correlated with chronological age—the greatest risk factor for Alzheimer's disease (AD). Genetic and environmental risk factors exist for AD, several of which are potentially modifiable. In this study, we assess the relationship between the epigenetic clock and AD risk factors.

Methods

Multilevel models were used to assess the relationship between age acceleration (the residual of biological age regressed onto chronological age) and AD risk factors relating to cognitive reserve, lifestyle, disease, and genetics in the Generation Scotland study (n = 5100).

Results

We report significant associations between age acceleration and body mass index, total cholesterol to high-density lipoprotein cholesterol ratios, socioeconomic status, high blood pressure, and smoking behavior (Bonferroni-adjusted P < .05).

Discussion

Associations are present between environmental risk factors for AD and age acceleration. Measures to modify such risk factors might improve the risk profile for AD and the rate of biological ageing. Future longitudinal analyses are therefore warranted.

Cerebral Hypoperfusion and Other Shared Brain Pathologies in Ischemic Stroke and Alzheimer's Disease

Newly emerged evidence reveals that ischemic stroke and Alzheimer's disease (AD) share pathophysiological changes in brain tissue including hypoperfusion, oxidative stress, immune exhaustion, and inflammation. A mechanistic link between hypoperfusion and amyloid β accumulation can lead to cell damage as well as to motor and cognitive deficits. This review will discuss decreased cerebral perfusion and other related pathophysiological changes common to both ischemic stroke and AD, such as vascular damages, cerebral blood flow alteration, abnormal expression of amyloid β and tau proteins, as well as behavioral and cognitive deficits. Furthermore, this review highlights current treatment options and potential therapeutic targets that warrant further investigation.

Regional myocardial motion in patients with mild cognitive impairment: a pilot study

Background

Cardiovascular disease (CVD) is a risk factor for cognitive impairment in the elderly. Manifestations of subclinical CVDs can be found in patients with cognitive impairment. The aim of the present study was to test the hypothesis that patients with mild cognitive impairment (MCI) have different magnetic resonance imaging (MRI)-derived regional myocardial motion indices compared with healthy controls.

Methods

Eleven MCI patients (age, 65.5 years ±5.9; range, 55–81 years old) and 11 sex−/age-matched healthy volunteers were enrolled. All of the participants underwent a head MRI and cardiac MRI. Global cortical atrophy (GCA) was graded on the head MRI. The left ventricular ejection fraction (LVEF) and regional strain, strain rate, displacement and velocity were measured on cine images. The GCA scores, global cardiac function and regional myocardial motion indices were compared between MCI patients and healthy controls using the t-test.

Results

MCI patients had a higher GCA score than healthy controls (p = 0.048). However, there was no significant difference in LVEF between MCI patients and controls. Compared to healthy controls, MCI patients had a lower peak radial strain (29.1% ± 24.1% vs. 46.4% ± 43.4%, p < 0.001), lower peak diastolic radial strain rate (3.2 ± 2.4 s^− 1 vs. 6.0 ± 3.0 s^− 1, p < 0.001), lower peak diastolic circumferential strain rate (2.5 ± 2.1 s^− 1 vs. 3.2 ± 2.1 s^− 1, p = 0.002), lower peak systolic radial displacement (4.2 ± 2.2 mm vs. 5.2 ± 3.3 mm, p = 0.002), lower peak diastolic radial velocity (31 ± 18 mm/s vs. 45 ± 33 mm/s, p < 0.001), and lower peak diastolic circumferential velocity (178 ± 124 degree/s vs. 217 ± 131 degree/s, p = 0.005).

Conclusion

MRI-derived regional myocardial strain, strain rate and velocity were found to be different between MCI patients and healthy controls. Regional myocardial motion indices have the potential to become novel quantitative imaging biomarkers for representing the risk of neurodegenerative disorders, such as Alzheimer’s disease (AD).

Electronic supplementary material

The online version of this article (10.1186/s12872-018-0824-2) contains supplementary material, which is available to authorized users.

18F-florbetapir Positron Emission Tomography-determined Cerebral β-Amyloid Deposition and Neurocognitive Performance after Cardiac Surgery

BACKGROUND

Amyloid deposition is a potential contributor to postoperative cognitive dysfunction. The authors hypothesized that 6-week global cortical amyloid burden, determined by F-florbetapir positron emission tomography, would be greater in those patients manifesting cognitive dysfunction at 6 weeks postoperatively.

METHODS

Amyloid deposition was evaluated in cardiac surgical patients at 6 weeks (n = 40) and 1 yr (n = 12); neurocognitive function was assessed at baseline (n = 40), 6 weeks (n = 37), 1 yr (n = 13), and 3 yr (n = 9). The association of 6-week amyloid deposition with cognitive dysfunction was assessed by multivariable regression, accounting for age, years of education, and baseline cognition. Differences between the surgical cohort with cognitive deficit and the Alzheimer's Disease Neuroimaging Initiative cohorts (normal and early/late mild cognitive impairment) was assessed, adjusting for age, education, and apolipoprotein E4 genotype.

RESULTS

The authors found that 6-week abnormal global cortical amyloid deposition was not associated with cognitive dysfunction (13 of 37, 35%) at 6 weeks postoperatively (median standard uptake value ratio [interquartile range]: cognitive dysfunction 0.92 [0.89 to 1.07] vs. 0.98 [0.93 to 1.05]; P = 0.455). In post hoc analyses, global cortical amyloid was also not associated with cognitive dysfunction at 1 or 3 yr postoperatively. Amyloid deposition at 6 weeks in the surgical cohort was not different from that in normal Alzheimer's Disease Neuroimaging Initiative subjects, but increased over 1 yr in many areas at a rate greater than in controls.

CONCLUSIONS

In this study, postoperative cognitive dysfunction was not associated with 6-week cortical amyloid deposition. The relationship between cognitive dysfunction and regional amyloid burden and the rate of postoperative amyloid deposition merit further investigation.

Protocol for a pragmatic randomised controlled trial of Body Brain Life-General Practice and a Lifestyle Modification Programme to decrease dementia risk exposure in a primary care setting

INTRODUCTION

It has been estimated that a 10%-25% reduction in seven key risk factors could potentially prevent 1.1-3.0 million Alzheimer's disease cases globally. In addition, as dementia is preceded by more subtle cognitive deficits which have substantial social and economic impact, effective preventative interventions would likely have more extensive benefits. The current study evaluates in primary care a multidomain risk-reduction intervention targeting adults with high risk of developing dementia.

METHODS AND ANALYSIS

A randomised controlled trial (RCT) is being conducted to evaluate three intervention programmes using a pragmatic approach suitable to the clinic: (1) a 12-week online and face-to-face dementia risk-reduction intervention (Body Brain Life-General Practice (BBL-GP)); (2) a 6-week face-to-face group lifestyle modification programme (LMP); and (3) a 12-week email-only programme providing general health information. We aim to recruit 240 participants, aged 18 and over, to undergo a comprehensive cognitive and physical assessment at baseline and follow-ups (postintervention, 18, 36 and 62 weeks). The primary outcome is dementia risk measured with the modified version of the Australian National University-Alzheimer's Disease Risk Index Short Form. Secondary outcomes are cognitive function measured with Trails A and B, and the Digit Symbol Modalities Test; physical activity with moderate-vigorous physical activity and the International Physical Activity Questionnaire; depression with the Centre for Epidemiological Studies Depression; cost evaluation with the 12-item Short Form Health Survey, Framingham Coronary Heart Disease Risk Score and Australian Type 2 Diabetes Risk Assessment Tool; diet quality with the Australian Recommended Food Score; and sleep quality with the Pittsburgh Sleep Quality Index.

ETHICS AND DISSEMINATION

This RCT is a novel pragmatic intervention applied in a primary care setting to reduce the dementia risk exposure in adults at high risk. If successful, BBL-GP and LMP will provide a versatile, evidence-based package that can be easily and quickly rolled out to other primary care settings and which can be scaled up at relatively low cost compared with other strategies involving intensive interventions.

TRIAL REGISTRATION NUMBER

ACTRN12616000868482.

The technical reliability and biotemporal stability of cerebrospinal fluid biomarkers for profiling multiple pathophysiologies in Alzheimer's disease

OBJECTIVE

Alzheimer's disease (AD) is a complex neurodegenerative disease driven by multiple interacting pathophysiological processes that ultimately results in synaptic loss, neuronal death, and dementia. We implemented a fit-for-purpose modeled approach to qualify a broad selection of commercially available immunoassays and evaluate the biotemporal stability of analytes across five pathophysiological domains of interest in AD, including core amyloid-β (Aβ) and tau AD biomarkers, neurodegeneration, inflammation/immune modulation, neurovascular injury, and metabolism/oxidative stress.

METHODS

Paired baseline and eight-week CSFs from twenty participants in a clinical drug trial for mild cognitive impairment (MCI) or mild dementia due to AD were used to evaluate sensitivity, intra-assay precision, inter-assay replicability, and eight-week biotemporal stability for sixty unique analytes measured with commercially available single- and multi-plex ELISA assays. Coefficients of variation (CV) were calculated, and intraclass correlation and Wilcoxon signed rank tests were applied.

RESULTS

We identified 32 biomarker candidates with good to excellent performance characteristics according to assay technical performance and CSF analyte biotemporal stability cut-off criteria. These included: 1) the core AD biomarkers Aβ1-42, Aβ1-40, Aβ1-38, and total tau; 2) non-Aβ, non-tau neurodegeneration markers NfL and FABP3; 3) inflammation/immune modulation markers IL-6, IL-7, IL-8, IL-12/23p40, IL-15, IL-16, MCP-1, MDC, MIP-1β, and YKL-40; 4) neurovascular markers Flt-1, ICAM-1, MMP-1, MMP-2, MMP-3, MMP-10, PlGF, VCAM-1, VEGF, VEGF-C, and VEGF-D; and 5) metabolism/oxidative stress markers 24-OHC, adiponectin, leptin, soluble insulin receptor, and 8-OHdG.

CONCLUSIONS

Assays for these CSF analytes demonstrate consistent sensitivity, reliability, and biotemporally stability for use in a multiple pathophysiological CSF biomarker panel to profile AD. Their qualification enables further investigation for use in AD diagnosis, staging and progression, disease mechanism profiling, and clinical trials.

Oxidative Stress Assessment in Alzheimer's Disease: A Clinic Setting Study

BACKGROUND

Oxidative stress (OS) is a physiological age-related brain process, dramatically overexpressed in neurodegenerative disorders like Alzheimer's disease (AD). Nevertheless, the pathophysiological role of OS in AD pathology has not been clarified yet. OS as a biomarker for AD is a controversial issue. A comparison of previous data is difficult due to a remarkable methodological variability. Most of the previous studies have shown higher levels of OS markers and lower antioxidant power in patients with dementia when compared to mild cognitive impairment (MCI) and healthy controls.

METHODS

We followed a strict protocol in order to limit intrasite variability of OS assessment. In addition, we have taken into account possible confounding factors.

RESULTS

In agreement with previous reports, we found both lower plasmatic OS and higher plasmatic antioxidant defenses when comparing patients with AD having dementia that is stably treated to patients with MCI-AD.

DISCUSSION

A speculative hypothesis based on correlative data is provided.

Undetected Peripheral Arterial Disease Among Older Adults With Alzheimer's Disease and Other Dementias

BACKGROUND

Peripheral arterial disease (PAD) was reported to increase the risk of dementia(s) even more than stroke. We assessed the prevalence of PAD in a group with definite diagnosis of dementia.

METHODS

Patients aged 65 years or older with Alzheimer's disease (AD), vascular dementia (VaD), or AD-VaD were enrolled (n = 162, mean age: 78.87 [6.05] years). An age- and gender-matched control group was also included (n = 190). Peripheral arterial disease was diagnosed by the ankle-brachial index.

RESULTS

Frequency of PAD among patients with and without dementia was 35.2% and 16.3%, respectively ( P < .001), being similar among different types of dementia. After adjustment for covariates, dementia (odds ratio: 2.41, 95% confidence interval: 1.34-4.32; P = .003) was among the predictors of PAD diagnosis along with older age, female gender, and diabetes.

CONCLUSIONS

The prevalence of PAD was more than double in patients with dementia, with no difference among AD, VaD, and AD-VaD types.

Review: Impact of Helicobacter pylori on Alzheimer's disease: What do we know so far?

BACKGROUND

Helicobacter pylori has changed radically gastroenterologic world, offering a new concept in patients' management. Over time, more medical data gave rise to diverse distant, extragastric manifestations and interactions of the "new" discovered bacterium. Special interest appeared within the field of neurodegenerative diseases and particularly Alzheimer's disease, as the latter and Helicobacter pylori infection are associated with a large public health burden and Alzheimer's disease ranks as the leading cause of disability. However, the relationship between Helicobacter pylori infection and Alzheimer's disease remains uncertain.

METHODS

We performed a narrative review regarding a possible connection between Helicobacter pylori and Alzheimer's disease. All accessible relevant (pre)clinical studies written in English were included. Both affected pathologies were briefly analyzed, and relevant studies are discussed, trying to focus on the possible pathogenetic role of this bacterium in Alzheimer's disease.

RESULTS

Data stemming from both epidemiologic studies and animal experiments seem to be rather encouraging, tending to confirm the hypothesis that Helicobacter pylori infection might influence the course of Alzheimer's disease pleiotropically. Possible main mechanisms may include the bacterium's access to the brain via the oral-nasal-olfactory pathway or by circulating monocytes (infected with Helicobacter pylori due to defective autophagy) through disrupted blood-brain barrier, thereby possibly triggering neurodegeneration.

CONCLUSIONS

Current data suggest that Helicobacter pylori infection might influence the pathophysiology of Alzheimer's disease. However, further large-scale randomized controlled trials are mandatory to clarify a possible favorable effect of Helicobacter pylori eradication on Alzheimer's disease pathophysiology, before the recommendation of short-term and cost-effective therapeutic regimens against Helicobacter pylori-related Alzheimer's disease.

Improvement of postoperative cognitive dysfunction and attention network function of patients with ischemic cerebrovascular disease via dexmedetomidine

The protective effect of dexmedetomidine on cognitive dysfunction and decreased attention network function of patients with ischemic cerebrovascular disease after stenting was investigated. Fifty-eight patients with ischemic cerebrovascular disease undergoing stenting in Guizhou Provincial People's Hospital were selected and randomly divided into control group (n=29) and dexmedetomidine group (n=29). The dexmedetomidine group was treated with dexmedetomidine before induced anesthesia, while the control group was given the same dose of normal saline; and the normal volunteers of the same age were selected as the normal group (n=29). At 3 days after operation, the levels of serum S100B and nerve growth factor (NGF) in each group were detected using the enzyme-linked immunosorbent assay, and the level of brain-derived neurotrophic factor (BDNF) was detected via western blotting. Montreal cognitive assessment (MoCA) and attention network test (ANT) were performed. Moreover, the cognitive function and attention network function, and the effects of dexmedetomidine on cognitive function and attention network function were evaluated. The concentrations of serum S100B and NGF in dexmedetomidine group was lower than those in control group (P<0.01). The results of western blotting showed that the levels of serum BDNF in control group and dexmedetomidine group were significantly lower than that in normal group (P<0.01), and it was higher in dexmedetomidine group than that in control group (P<0.01). Besides, both MoCA and ANT results revealed that the visual space and executive function scores, attention scores, delayed memory scores, targeted network efficiency and executive control network efficiency in dexmedetomidine group were obviously higher than those in control group (P<0.01). The cognitive function and attention network function of patients with ischemic cerebrovascular disease have a certain degree of damage, and the preoperative administration of dexmedetomidine can effectively improve the patient's cognitive dysfunction and attention network function after operation.

Metabolic Risk Factors of Alzheimer's Disease, Dementia with Lewy Bodies, and Normal Elderly: A Population-Based Study

BACKGROUND

Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) share many risk factors. Evidence suggests that metabolic risk factors are important to AD; however, their association with DLB is unclear. The risk of cardiovascular diseases (CVD) associated with AD and DLB is also uncertain. Thus, this nationwide, population-based study was designed to evaluate the metabolic and CVD risks in AD and DLB.

MATERIALS AND METHODS

Data were obtained from the Taiwan National Health Insurance Research Database. AD patients, DLB patients, and normal control (NC) individuals from 1996 to 2013 were enrolled for risk assessment.

RESULTS

In total, 7544 NC individuals, 1324 AD patients, and 562 DLB patients were enrolled. Participants with one or more metabolic risk factors had significantly higher odds of AD or DLB. No significant differences in metabolic risk factors were observed between DLB and AD patients. AD patients had a lower risk of CVD (aHR = 0.67, 95% CI = 0.59-0.76, p value < 0.001) and coronary artery disease (CAD) (aHR = 0.59, 95% CI = 0.51-0.69, p value < 0.001) than NC. DLB patients had a higher risk of ischemic stroke (aHR = 2.27, 95% CI = 1.68-3.06, p value < 0.001) than NC.

CONCLUSION

Metabolic risk factors are important in AD and DLB. Patients with AD might have a lower risk of CAD and ischemic strokes. Patients with DLB might have a higher risk of ischemic stroke.

Therapeutic Potential of Ursolic Acid to Manage Neurodegenerative and Psychiatric Diseases

Ursolic acid is a pentacyclic triterpenoid found in several plants. Despite its initial use as a pharmacologically inactive emulsifier in pharmaceutical, cosmetic and food industries, several biological activities have been reported for this compound so far, including anti-tumoural, anti-diabetic, cardioprotective and hepatoprotective properties. The biological effects of ursolic acid have been evaluated in vitro, in different cell types and against several toxic insults (i.e. 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, amyloid-β peptides, kainic acid and others); in animal models of brain-related disorders (Alzheimer disease, Parkinson disease, depression, traumatic brain injury) and ageing; and in clinical studies with cancer patients and for muscle atrophy. Most of the protective effects of ursolic acid are related to its ability to prevent oxidative damage and excessive inflammation, common mechanisms associated with multiple brain disorders. Additionally, ursolic acid is capable of modulating the monoaminergic system, an effect that might be involved in its ability to prevent mood and cognitive dysfunctions associated with neurodegenerative and psychiatric conditions. This review presents and discusses the available evidence of the possible beneficial effects of ursolic acid for the management of neurodegenerative and psychiatric disorders. We also discuss the chemical features, major sources and potential limitations of the use of ursolic acid as a pharmacological treatment for brain-related diseases.

Pericyte implantation in the brain enhances cerebral blood flow and reduces amyloid-β pathology in amyloid model mice

Pericytes are a major component of cerebrovasculature playing a key role in maintaining cerebrovascular homeostasis. These cells have also been suggested to regulate brain metabolism of amyloid-β (Aβ), disturbances of which are believed to contribute to the pathogenesis of Alzheimer's disease (AD). To examine the effects of pericytes on brain Aβ metabolism, C3H/10T1/2 mouse mesenchymal stem cells were differentiated into pericytes and stereotaxically injected into the brains of amyloid AD model APP/PS1 mice at the age of 18 to 20months. Consistent with a role of pericytes in modulating cerebrovascular function, brain microcirculation in the pericyte-injected hemisphere of the mice was increased 3weeks after implantation compared to the contralateral hemisphere when measured by laser speckle contrast analysis technology. Importantly, enzyme-linked immunosorbent assay revealed that the levels of insoluble Aβ40 and Aβ42 were significantly lower in the hippocampus of the pericyte-injected hemisphere of the APP/PS1 mice than that of the contralateral side. Consistently, immunohistochemical analysis demonstrated that the pericyte implantation reduced Aβ deposition in the hippocampus. When brain slices from the APP/PS1 mice were incubated with C3H/10T1/2 cell-derived pericytes, Aβ42 levels were significantly reduced in a manner that depends on the expression of a major Aβ endocytic receptor, the low-density lipoprotein receptor-related protein 1 (LRP1). While LRP1 mediated the cellular uptake of Aβ in the pericytes, the amounts of major Aβ-degrading enzymes were not affected by LRP1 knockdown. Together, our findings indicate that mesenchymal stem cell-derived pericytes have the capacity to reduce brain Aβ and related pathology, and suggest that cell-based therapy through transplantation of pericytes may be a promising approach to prevent and/or treat AD.

Motoric Cognitive Risk Syndrome: Predictor of Dementia and Age-Related Negative Outcomes

Cognitive disorders represent a leading cause of disability in the aging population, of which dementia has the highest global burden. Early signs of dementia such as slow gait and memory complaints are known to present well before the overt manifestation of the disease. Motoric cognitive risk (MCR) syndrome characterized by the simultaneous presence of gait disturbances and memory complaints in older subjects has been proposed to study the close interactions between the physical and cognitive domains as well as a possible approach to identify individuals at increased risk of dementia. In addition, studies have shown MCR as a predictor of other negative outcomes in older adults, including disability, falls and death. However, the concept of MCR is still in its early stage and approach to the syndrome is still not well established. This review aims to put together the various aspects of MCR syndrome including its pathophysiology, diagnosis, epidemiology, and relationship with other geriatric conditions.

Weighting and standardization of frequencies to determine prevalence of AD imaging biomarkers

OBJECTIVE

To estimate the prevalence of elevated brain amyloid and reduced cortical thickness (as a marker for neurodegeneration) in a defined population.

METHODS

Mayo Clinic Study of Aging participants underwent MRI to assess a composite Alzheimer disease (AD) signature cortical thickness measure and PET to assess brain amyloid accumulation. Participants were characterized as having elevated amyloid (A+/A-), reduced cortical thickness (N+/N-), and A+N+, A+N-, A-N+, or A-N-. The prevalence of AD biomarkers was derived by adjusting for nonparticipation and standardizing to the Olmsted County, Minnesota, population.

RESULTS

Among 1,646 participants without dementia (mean age 70.8 years; 53.2% men), the prevalence (95% confidence interval) of amyloidosis was 21.1% (19.1%-23.2%): women, 24.3%; men, 17.5%. The prevalence of reduced cortical thickness was 28.9% (26.4%-31.5%): women, 27.9%; men, 30.2%. The prevalence estimates of biomarker categories were as follows: A-N-: 61.4%; A+N-: 9.7%; A-N+: 17.4%; and A+N+: 11.5%, and varied by sex and by APOE ε4 carrier status. In men, prevalence estimates were as follows: A-N-: 62.6%; A+N-: 7.3%; A-N+: 19.9%; and A+N+: 10.2%. In women, prevalence estimates were as follows: A-N-: 60.4%; A+N-: 11.7%; A-N+: 15.3%; and A+N+: 12.6%. In ε4 carriers, prevalence estimates were as follows: A-N-: 54.6%; A+N-: 16.6%; A-N+: 12.4%; and A+N+: 16.4%. In non-ε4 carriers, prevalence estimates were as follows: A-N-: 63.3%; A+N-: 6.9%; A-N+: 19.9%; and A+N+: 10.0%.

CONCLUSIONS

These prevalence estimates are important for understanding age-related trends in amyloid positivity and AD signature cortical thickness in the population, and for potentially projecting the future burden of biomarkers in elderly persons.

The Decrease of Uch-L1 Activity Is a Common Mechanism Responsible for Aβ 42 Accumulation in Alzheimer's and Vascular Disease

Alzheimer’s disease (AD) is a multifactorial pathology causing common brain spectrum disorders in affected patients. These mixed neurological disorders not only include structural AD brain changes but also cerebrovascular lesions. The main aim of the present issue is to find the factors shared by the two pathologies. The decrease of ubiquitin C-terminal hydrolase L1 (Uch-L1), a major neuronal enzyme involved in the elimination of misfolded proteins, was observed in ischemic injury as well as in AD, but its role in the pathogenesis of AD is far to be clear. In this study we demonstrated that Uch-L1 inhibition induces BACE1 up-regulation and increases neuronal and apoptotic cell death in control as well as in transgenic AD mouse model subjected to Bengal Rose, a light-sensitive dye inducing that induces a cortical infarction through photo-activation. Under the same conditions we also found a significant activation of NF-κB. Thus, the restoration of Uch-L1 was able to completely prevent both the increase in BACE1 protein levels and the amount of cell death. Our data suggest that the Uch-L1-mediated BACE1 up-regulation could be an important mechanism responsible for Aβ peptides accumulation in vascular injury and indicate that the modulation of the activity of this enzyme could provide new therapeutic strategies in AD.

Cognitive behavioral therapy (CBT) for preventing Alzheimer's disease

This review provides the rationale for implementing cognitive behavioral therapy (CBT) for the prevention of Alzheimer's disease (AD). There are known risk factors associated with the development of AD, some of which may be ameliorated with CBT. We posit that treating the risk factors of inactivity, poor diet, hyposmia and anosmia, sleep disorders and lack of regularly engaged challenging cognitive activity will modify the physiology of the brain sufficiently to avoid the accumulation of excess proteins, including amyloid beta, causal events in the development of AD. Further, the successful treatment of the listed risk factors is well within our technology to do so and, even further, it is cost effective. Also, there is considerable scientific literature to support the proposition that, if implemented by well-established practices, CBT will be effective and will be engaged by those of retirement age. That is, we present a biologically informed CBT for the prevention of the development of AD, i.e., an aspect of applied behavioral neuroscience.

Blood-Brain Barrier Dysfunction and the Pathogenesis of Alzheimer's Disease

Brain capillary endothelial cells form the blood-brain barrier (BBB), which is covered with basement membranes and is also surrounded by pericytes and astrocyte end-feet in the neurovascular unit. The BBB tightly regulates the molecular exchange between the blood flow and brain parenchyma, thereby regulating the homeostasis of the central nervous system (CNS). Thus, dysfunction of the BBB is likely involved in the pathogenesis of several neurological diseases, including Alzheimer’s disease (AD). While amyloid-β (Aβ) deposition and neurofibrillary tangle formation in the brain are central pathological hallmarks in AD, cerebrovascular lesions and BBB alteration have also been shown to frequently coexist. Although further clinical studies should clarify whether BBB disruption is a specific feature of AD pathogenesis, increasing evidence indicates that each component of the neurovascular unit is significantly affected in the presence of AD-related pathologies in animal models and human patients. Conversely, since some portions of Aβ are eliminated along the neurovascular unit and across the BBB, disturbing the pathways may result in exacerbated Aβ accumulation in the brain. Thus, current evidence suggests that BBB dysfunction may causatively and consequently contribute to AD pathogenesis, forming a vicious cycle between brain Aβ accumulation and neurovascular unit impairments during disease progression.

Rho-associated protein kinases as therapeutic targets for both vascular and parenchymal pathologies in Alzheimer's disease

The causes of late-onset Alzheimer's disease are unclear and likely multifactorial. Rho-associated protein kinases (ROCKs) are ubiquitously expressed signaling messengers that mediate a wide array of cellular processes. Interestingly, they play an important role in several vascular and brain pathologies implicated in Alzheimer's etiology, including hypertension, hypercholesterolemia, blood-brain barrier disruption, oxidative stress, deposition of vascular and parenchymal amyloid-beta peptides, tau hyperphosphorylation, and cognitive decline. The current review summarizes the functions of ROCKs with respect to the various risk factors and pathologies on both sides of the blood-brain barrier and present support for targeting ROCK signaling as a multifactorial and multi-effect approach for the prevention and amelioration of late-onset Alzheimer's disease. This article is part of the Special Issue "Vascular Dementia".

The Exceptional Vulnerability of Humans to Alzheimer's Disease

Like many humans, non-human primates deposit copious misfolded Aβ protein in the brain as they age. Nevertheless, the complete behavioral and pathologic phenotype of Alzheimer's disease, including Aβ plaques, neurofibrillary (tau) tangles, and dementia, has not yet been identified in a non-human species. Recent research suggests that the crucial link between Aβ aggregation and tauopathy is somehow disengaged in aged monkeys. Understanding why Alzheimer's disease fails to develop in species that are biologically proximal to humans could disclose new therapeutic targets in the chain of events leading to neurodegeneration and dementia.