Prevalence of dementia disorders in the oldest-old: an autopsy study

Limbic-predominant age-related TDP-43 encephalopathy (LATE-NC): Co-pathologies and genetic risk factors provide clues about pathogenesis

Limbic-predominant age-related TDP-43 encephalopathy neuropathologic change (LATE-NC) is detectable at autopsy in more than one-third of people beyond age 85 years and is robustly associated with dementia independent of other pathologies. Although LATE-NC has a large impact on public health, there remain uncertainties about the underlying biologic mechanisms. Here, we review the literature from human studies that may shed light on pathogenetic mechanisms. It is increasingly clear that certain combinations of pathologic changes tend to coexist in aging brains. Although "pure" LATE-NC is not rare, LATE-NC often coexists in the same brains with Alzheimer disease neuropathologic change, brain arteriolosclerosis, hippocampal sclerosis of aging, and/or age-related tau astrogliopathy (ARTAG). The patterns of pathologic comorbidities provide circumstantial evidence of mechanistic interactions ("synergies") between the pathologies, and also suggest common upstream influences. As to primary mediators of vulnerability to neuropathologic changes, genetics may play key roles. Genes associated with LATE-NC include TMEM106B, GRN, APOE, SORL1, ABCC9, and others. Although the anatomic distribution of TDP-43 pathology defines the condition, important cofactors for LATE-NC may include Tau pathology, endolysosomal pathways, and blood-brain barrier dysfunction. A review of the human phenomenology offers insights into disease-driving mechanisms, and may provide clues for diagnostic and therapeutic targets.

2024 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease (AD), including prevalence and incidence, mortality and morbidity, use and costs of care and the ramifications of AD for family caregivers, the dementia workforce and society. The Special Report discusses the larger health care system for older adults with cognitive issues, focusing on the role of caregivers and non-physician health care professionals. An estimated 6.9 million Americans age 65 and older are living with Alzheimer's dementia today. This number could grow to 13.8 million by 2060, barring the development of medical breakthroughs to prevent or cure AD. Official AD death certificates recorded 119,399 deaths from AD in 2021. In 2020 and 2021, when COVID-19 entered the ranks of the top ten causes of death, Alzheimer's was the seventh-leading cause of death in the United States. Official counts for more recent years are still being compiled. Alzheimer's remains the fifth-leading cause of death among Americans age 65 and older. Between 2000 and 2021, deaths from stroke, heart disease and HIV decreased, whereas reported deaths from AD increased more than 140%. More than 11 million family members and other unpaid caregivers provided an estimated 18.4 billion hours of care to people with Alzheimer's or other dementias in 2023. These figures reflect a decline in the number of caregivers compared with a decade earlier, as well as an increase in the amount of care provided by each remaining caregiver. Unpaid dementia caregiving was valued at $346.6 billion in 2023. Its costs, however, extend to unpaid caregivers' increased risk for emotional distress and negative mental and physical health outcomes. Members of the paid health care and broader community-based workforce are involved in diagnosing, treating and caring for people with dementia. However, the United States faces growing shortages across different segments of the dementia care workforce due to a combination of factors, including the absolute increase in the number of people living with dementia. Therefore, targeted programs and care delivery models will be needed to attract, better train and effectively deploy health care and community-based workers to provide dementia care. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are almost three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 22 times as great. Total payments in 2024 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $360 billion. The Special Report investigates how caregivers of older adults with cognitive issues interact with the health care system and examines the role non-physician health care professionals play in facilitating clinical care and access to community-based services and supports. It includes surveys of caregivers and health care workers, focusing on their experiences, challenges, awareness and perceptions of dementia care navigation.

Interactions between vascular burden and amyloid-β pathology on trajectories of tau accumulation

Cerebrovascular pathology often co-exists with Alzheimer's disease pathology and can contribute to Alzheimer's disease-related clinical progression. However, the degree to which vascular burden contributes to Alzheimer's disease pathological progression is still unclear. This study aimed to investigate interactions between vascular burden and amyloid-β pathology on both baseline tau tangle load and longitudinal tau accumulation. We included 1229 participants from the Swedish BioFINDER-2 Study, including cognitively unimpaired and impaired participants with and without biomarker-confirmed amyloid-β pathology. All underwent baseline tau-PET (18F-RO948), and a subset (n = 677) underwent longitudinal tau-PET after 2.5 ± 1.0 years. Tau-PET uptake was computed for a temporal meta-region-of-interest. We focused on four main vascular imaging features and risk factors: microbleeds; white matter lesion volume; stroke-related events (infarcts, lacunes and haemorrhages); and the Framingham Heart Study Cardiovascular Disease risk score. To validate our in vivo results, we examined 1610 autopsy cases from an Arizona-based neuropathology cohort on three main vascular pathological features: cerebral amyloid angiopathy; white matter rarefaction; and infarcts. For the in vivo cohort, primary analyses included age-, sex- and APOE ɛ4-corrected linear mixed models between tau-PET (outcome) and interactions between time, amyloid-β and each vascular feature (predictors). For the neuropathology cohort, age-, sex- and APOE ɛ4-corrected linear models between tau tangle density (outcome) and an interaction between plaque density and each vascular feature (predictors) were performed. In cognitively unimpaired individuals, we observed a significant interaction between microbleeds and amyloid-β pathology on greater baseline tau load (β = 0.68, P < 0.001) and longitudinal tau accumulation (β = 0.11, P < 0.001). For white matter lesion volume, we did not observe a significant independent interaction effect with amyloid-β on tau after accounting for microbleeds. In cognitively unimpaired individuals, we further found that stroke-related events showed a significant negative interaction with amyloid-β on longitudinal tau (β = -0.08, P < 0.001). In cognitively impaired individuals, there were no significant interaction effects between cerebrovascular and amyloid-β pathology at all. In the neuropathology dataset, the in vivo observed interaction effects between cerebral amyloid angiopathy and plaque density (β = 0.38, P < 0.001) and between infarcts and plaque density (β = -0.11, P = 0.005) on tau tangle density were replicated. To conclude, we demonstrated that cerebrovascular pathology-in the presence of amyloid-β pathology-modifies tau accumulation in early stages of Alzheimer's disease. More specifically, the co-occurrence of microbleeds and amyloid-β pathology was associated with greater accumulation of tau aggregates during early disease stages. This opens the possibility that interventions targeting microbleeds may attenuate the rate of tau accumulation in Alzheimer's disease.

Apolipoprotein E Gene in α-Synucleinopathies: A Narrative Review

In this narrative review, we delved into the intricate interplay between Apolipoprotein E (APOE) alleles (typically associated with Alzheimer's disease-AD) and alpha-synucleinopathies (aS-pathies), involving Parkinson's disease (PD), Parkinson's disease dementia (PDD), dementia with Lewy bodies (DLB), and multiple-system atrophy (MSA). First, in-vitro, animal, and human-based data on the exacerbating effect of APOE4 on LB pathology were summarized. We found robust evidence that APOE4 carriage constitutes a risk factor for PDD-APOE2, and APOE3 may not alter the risk of developing PDD. We confirmed that APOE4 copies confer an increased hazard towards DLB, as well. Again APOE2 and APOE3 appear unrelated to the risk of conversion. Of note, in individuals with DLB APOE4, carriage appears to be intermediately prevalent between AD and PDD-PD (AD > DLB > PDD > PD). Less consistency existed when it came to PD; APOE-PD associations tended to be markedly modified by ethnicity. Finally, we failed to establish an association between the APOE gene and MSA. Phenotypic associations (age of disease onset, survival, cognitive-neuropsychiatric- motor-, and sleep-related manifestations) between APOE alleles, and each of the aforementioned conditions were also outlined. Finally, a synopsis of literature gaps was provided followed by suggestions for future research.

Alterations of White Matter Connectivity in Adults with Essential Hypertension

Purpose

To explore the topology of the white matter network in individuals with essential hypertension by graph theory.

Patients and Methods

T1-weighted image and diffusion tensor imaging (DTI) data from 43 patients diagnosed with essential hypertension (EHT) and 33 individuals with normotension (healthy controls, HCs) were incorporated in this cross-sectional study. Furthermore, structural networks were constructed by graph theory to calculate whole brain network characteristics and intracerebral node characteristics.

Results

Both EHT and HC groups displayed small-worldness in their structural networks. The area under the curve (AUC) of the small-worldness coefficient (σ) was higher in the EHT group compared to the HC group, whereas the AUC of assortativity was lower in the EHT group in contrast to the HC group. The nodal clustering coefficient (CP) and local efficiency (Eloc) of the EHT group decreased in the right dorsolateral superior frontal gyrus and the left medial superior frontal gyrus. These values increased in the left anterior cingulate and paracingulate gyrus. Furthermore, weight and body mass index (BMI) were positively correlated with σ.

Conclusion

The EHT group showed brain network separation and integration dysfunction. Weight and BMI were positively correlated with σ. The data acquired in this investigation implied that altered structural connectivity in the prefrontal region may be a potential neuroimaging marker in EHT patients.

Association of Glycemic Variability With Imaging Markers of Vascular Burden, β-Amyloid, Brain Atrophy, and Cognitive Impairment

BACKGROUND AND OBJECTIVE

We aimed to investigate the association between glycemic variability (GV) and neuroimaging markers of white matter hyperintensities (WMH), beta-amyloid (Aβ), brain atrophy, and cognitive impairment.

METHODS

This was a retrospective cohort study that included participants without dementia from a memory clinic. They all had Aβ PET, brain MRI, and standardized neuropsychological tests and had fasting glucose (FG) levels tested more than twice during the study period. We defined GV as the intraindividual visit-to-visit variability in FG levels. Multivariable linear regression and logistic regression were used to identify whether GV was associated with the presence of severe WMH and Aβ uptake with DM, mean FG levels, age, sex, hypertension, and presence of APOE4 allele as covariates. Mediation analyses were used to investigate the mediating effect of WMH and Aβ uptake on the relationship between GV and brain atrophy and cognition.

RESULTS

Among the 688 participants, the mean age was 72.2 years, and the proportion of female participants was 51.9%. Increase in GV was predictive of the presence of severe WMH (coefficient [95% CI] 1.032 [1.012-1.054]; p = 0.002) and increased Aβ uptake (1.005 [1.001-1.008]; p = 0.007). Both WMH and increased Aβ uptake partially mediated the relationship between GV and frontal-executive dysfunction (GV → WMH → frontal-executive; direct effect, -0.319 [-0.557 to -0.080]; indirect effect, -0.050 [-0.091 to -0.008]) and memory dysfunction (GV → Aβ → memory; direct effect, -0.182 [-0.338 to -0.026]; indirect effect, -0.067 [-0.119 to -0.015]), respectively. In addition, increased Aβ uptake completely mediated the relationship between GV and hippocampal volume (indirect effect, -1.091 [-2.078 to -0.103]) and partially mediated the relationship between GV and parietal thickness (direct effect, -0.00101 [-0.00185 to -0.00016]; indirect effect, -0.00016 [-0.00032 to -0.000002]).

DISCUSSION

Our findings suggest that increased GV is related to vascular and Alzheimer risk factors and neurodegenerative markers, which in turn leads to subsequent cognitive impairment. Furthermore, GV can be considered a potentially modifiable risk factor for dementia prevention.

An inclusive study of recent advancements in Alzheimer's disease: A comprehensive review

Alzheimer's disease (AD) has remained elusive in revealing its pathophysiology and mechanism of development. In this review paper, we attempt to highlight several theories that abound about the exact pathway of AD development. The number of cases worldwide has prompted a constant flow of research to detect high-risk patients, slow the progression of the disease and discover improved methods of treatment that may prove effective. We shall focus on the two main classes of drugs that are currently in use; and emerging ones with novel mechanisms that are under development. As of late there has also been increased attention towards factors that were previously thought to be unrelated to AD, such as the gut microbiome, lifestyle habits, and diet. Studies have now shown that all these factors make an impact on AD progression, thus bringing to our attention more areas that could hold the key to combating this disease. This paper covers all the aforementioned factors concisely. We also briefly explore the relationship between mental health and AD, both before and after the diagnosis of the disease.

When prion disease Isn't suspected: prion disease as the cause of terminal decline in chronic mixed dementia

Alzheimer's Disease (AD) is the most common cause of dementia, although multiple pathologies are found in nearly half of the cases with clinically diagnosed AD. Prion diseases, such as Creutzfeldt-Jakob disease (CJD), are rare causes of dementia and typically manifest as a rapidly progressive dementia, where symptom onset to dementia most often occurs over the course of months. In this brief report, we describe a patient's typically progressive dementia with a precipitous decline at the end of their life who, on neuropathological evaluation, was found to have multiple neurodegenerative proteinopathies as well as spongiform encephalopathy due to CJD. This case of unsuspected CJD highlights a rare, but epidemiologically important, cause of sudden decline in well-established neurodegenerative dementias.

2023 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease, including prevalence and incidence, mortality and morbidity, use and costs of care, and the overall impact on family caregivers, the dementia workforce and society. The Special Report examines the patient journey from awareness of cognitive changes to potential treatment with drugs that change the underlying biology of Alzheimer's. An estimated 6.7 million Americans age 65 and older are living with Alzheimer's dementia today. This number could grow to 13.8 million by 2060 barring the development of medical breakthroughs to prevent, slow or cure AD. Official death certificates recorded 121,499 deaths from AD in 2019, and Alzheimer's disease was officially listed as the sixth-leading cause of death in the United States. In 2020 and 2021, when COVID-19 entered the ranks of the top ten causes of death, Alzheimer's was the seventh-leading cause of death. Alzheimer's remains the fifth-leading cause of death among Americans age 65 and older. Between 2000 and 2019, deaths from stroke, heart disease and HIV decreased, whereas reported deaths from AD increased more than 145%. This trajectory of deaths from AD was likely exacerbated by the COVID-19 pandemic in 2020 and 2021. More than 11 million family members and other unpaid caregivers provided an estimated 18 billion hours of care to people with Alzheimer's or other dementias in 2022. These figures reflect a decline in the number of caregivers compared with a decade earlier, as well as an increase in the amount of care provided by each remaining caregiver. Unpaid dementia caregiving was valued at $339.5 billion in 2022. Its costs, however, extend to family caregivers' increased risk for emotional distress and negative mental and physical health outcomes - costs that have been aggravated by COVID-19. Members of the paid health care workforce are involved in diagnosing, treating and caring for people with dementia. In recent years, however, a shortage of such workers has developed in the United States. This shortage - brought about, in part, by COVID-19 - has occurred at a time when more members of the dementia care workforce are needed. Therefore, programs will be needed to attract workers and better train health care teams. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are almost three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 22 times as great. Total payments in 2023 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $345 billion. The Special Report examines whether there will be sufficient numbers of physician specialists to provide Alzheimer's care and treatment now that two drugs are available that change the underlying biology of Alzheimer's disease.

Incidence of Parkinson disease in North America

Parkinson disease (PD) is the second most common age-related neurodegenerative condition diagnosed in North America. We recently demonstrated, using multiple epidemiological data sources, that the prevalence of PD diagnoses was greater than previously reported and currently used for clinical, research, and policy decision-making. Prior PD incidence estimates have varied, for unclear reasons. There is a need for improved estimates of PD incidence, not only for care delivery planning and future policy but also for increasing our understanding of disease risk. The objective of this study was thus to investigate the incidence of Parkinson disease across five epidemiological cohorts in North America in a common year, 2012. The cohorts contained data on 6.7 million person-years of adults ages 45 and older, and 9.3 million person-years of adults ages 65 and older. Our estimates of age-sex-adjusted incidence of PD ranged from 108 to 212 per 100,000 among persons ages 65 and older, and from 47 to 77 per 100,00 among persons ages 45 and older. PD incidence increased with age and was higher among males. We also found persistent spatial clustering of incident PD diagnoses in the U.S. PD incidence estimates varied across our data sources, in part due to case ascertainment and diagnosis methods, but also possibly due to the influence of population factors (prevalence of genetic risk factors or protective markers) and geographic location (exposure to environmental toxins). Understanding the source of these variations will be important for health care policy, research, and care planning.

Cerebrospinal fluid catecholamines in Alzheimer's disease patients with and without biological disease

Noradrenergic and dopaminergic neurons are involved in cognitive functions, relate to behavioral and psychological symptoms in dementia and are affected in Alzheimer's disease (AD). Amyloid plaques (A), neurofibrillary tangles (T) and neurodegeneration (N) hallmarks the AD neuropathology. Today, the AT(N) pathophysiology can be assessed through biomarkers. Previous studies report cerebrospinal fluid (CSF) catecholamine concentrations in AD patients without biomarker refinement. We explored if CSF catecholamines relate to AD clinical presentation or neuropathology as reflected by CSF biomarkers. CSF catecholamines were analyzed in AD patients at the mild cognitive impairment (MCI; n = 54) or dementia stage (n = 240) and in cognitively unimpaired (n = 113). CSF biomarkers determined AT status and indicated synaptic damage (neurogranin). The AD patients (n = 294) had higher CSF noradrenaline and adrenaline concentrations, but lower dopamine concentrations compared to the cognitively unimpaired (n = 113). AD patients in the MCI and dementia stage of the disease had similar CSF catecholamine concentrations. In the CSF neurogranin positively associated with noradrenaline and adrenaline but not with dopamine. Adjusted regression analyses including AT status, CSF neurogranin, age, gender, and APOEε4 status verified the findings. In restricted analyses comparing A+T+ patients to A-T- cognitively unimpaired, the findings for CSF adrenaline remained significant (p < 0.001) but not for CSF noradrenaline (p = 0.07) and CSF dopamine (p = 0.33). There were no differences between A+T+ and A-T- cognitively unimpaired. Thus, we find alterations in CSF catecholamines in symptomatic AD and the CSF adrenergic transmitters to increase simultaneously with synaptic damage as indexed by CSF neurogranin.

2022 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease (AD), including incidence and prevalence, mortality and morbidity, use and costs of care, and the overall impact on family caregivers, the dementia workforce and society. The Special Report discusses consumers' and primary care physicians' perspectives on awareness, diagnosis and treatment of mild cognitive impairment (MCI), including MCI due to Alzheimer's disease. An estimated 6.5 million Americans age 65 and older are living with Alzheimer's dementia today. This number could grow to 13.8 million by 2060 barring the development of medical breakthroughs to prevent, slow or cure AD. Official death certificates recorded 121,499 deaths from AD in 2019, the latest year for which data are available. Alzheimer's disease was officially listed as the sixth-leading cause of death in the United States in 2019 and the seventh-leading cause of death in 2020 and 2021, when COVID-19 entered the ranks of the top ten causes of death. Alzheimer's remains the fifth-leading cause of death among Americans age 65 and older. Between 2000 and 2019, deaths from stroke, heart disease and HIV decreased, whereas reported deaths from AD increased more than 145%. More than 11 million family members and other unpaid caregivers provided an estimated 16 billion hours of care to people with Alzheimer's or other dementias in 2021. These figures reflect a decline in the number of caregivers compared with a decade earlier, as well as an increase in the amount of care provided by each remaining caregiver. Unpaid dementia caregiving was valued at $271.6 billion in 2021. Its costs, however, extend to family caregivers' increased risk for emotional distress and negative mental and physical health outcomes - costs that have been aggravated by COVID-19. Members of the dementia care workforce have also been affected by COVID-19. As essential care workers, some have opted to change jobs to protect their own health and the health of their families. However, this occurs at a time when more members of the dementia care workforce are needed. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are almost three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 22 times as great. Total payments in 2022 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $321 billion. A recent survey commissioned by the Alzheimer's Association revealed several barriers to consumers' understanding of MCI. The survey showed low awareness of MCI among Americans, a reluctance among Americans to see their doctor after noticing MCI symptoms, and persistent challenges for primary care physicians in diagnosing MCI. Survey results indicate the need to improve MCI awareness and diagnosis, especially in underserved communities, and to encourage greater participation in MCI-related clinical trials.

Pathological changes within the cerebral vasculature in Alzheimer's disease: New perspectives

Cerebrovascular disease underpins vascular dementia (VaD), but structural and functional changes to the cerebral vasculature contribute to disease pathology and cognitive decline in Alzheimer's disease (AD). In this review, we discuss the contribution of cerebral amyloid angiopathy and non‐amyloid small vessel disease in AD, and the accompanying changes to the density, maintenance and remodelling of vessels (including alterations to the composition and function of the cerebrovascular basement membrane). We consider how abnormalities of the constituent cells of the neurovascular unit – particularly of endothelial cells and pericytes – and impairment of the blood‐brain barrier (BBB) impact on the pathogenesis of AD. We also discuss how changes to the cerebral vasculature are likely to impair Aβ clearance – both intra‐periarteriolar drainage (IPAD) and transport of Aβ peptides across the BBB, and how impaired neurovascular coupling and reduced blood flow in relation to metabolic demand increase amyloidogenic processing of APP and the production of Aβ. We review the vasoactive properties of Aβ peptides themselves, and the probable bi‐directional relationship between vascular dysfunction and Aβ accumulation in AD. Lastly, we discuss recent methodological advances in transcriptomics and imaging that have provided novel insights into vascular changes in AD, and recent advances in assessment of the retina that allow in vivo detection of vascular changes in the early stages of AD.

Cognitive decline and diabetes: a systematic review of the neuropathological correlates accounting for cognition at death

Given conflicting findings in epidemiologic studies, we determined the relative contributions of different neuropathologies to the excess risk of cognitive decline in diabetes mellitus (DM) through a systematic review of the literature. Included studies compared subjects with and without DM and reported neuropathological outcomes accounting for cognition at death. Data on Alzheimer's disease (AD) pathology, cerebrovascular disease and non-vascular, non-AD pathology were extracted from each study. Eleven studies (n=6 prospective cohorts, n=5 retrospective post-mortem series, total n=6330) met inclusion criteria. All 11 studies quantified AD changes and 10/11 measured cerebrovascular disease: macroscopic lesions (n=9), microinfarcts (n=8), cerebral amyloid angiopathy (CAA, n=7), lacunes (n=6), white matter disease (n=5), haemorrhages (n=4), microbleeds (n=1), hippocampal microvasculature (n=1). Other pathology was infrequently examined. No study reported increased AD pathology in DM, three studies showed a decrease (n=872) and four (n= 4018) showed no difference, after adjustment for cognition at death. No study reported reduced cerebrovascular pathology in DM. Three studies (n=2345) reported an increase in large infarcts, lacunes and microinfarcts. One study found lower cognitive scores in DM compared to non-DM subjects despite similar cerebrovascular and AD-pathology load suggesting contributions from other neuropathological processes. In conclusion, lack of an association between DM and AD-related neuropathology was consistent across studies, irrespective of methodology. In contrast to AD, DM was associated with increased large and small vessel disease. Data on other pathologies such as non-AD neurodegeneration, and blood-brain-barrier breakdown were lacking. Further studies evaluating relative contributions of different neuropathologies to the excess risk of DM are needed.

Potential Roles of Glucagon-Like Peptide-1 and Its Analogues in Dementia Targeting Impaired Insulin Secretion and Neurodegeneration

Dementia is a chronic, irreversible condition marked by memory loss, cognitive decline, and mental instability. It is clinically related to various progressive neurological diseases, including Parkinson’s disease, Alzheimer’s disease, and Huntington’s. The primary cause of neurological disorders is insulin desensitization, demyelination, oxidative stress, and neuroinflammation accompanied by various aberrant proteins such as amyloid-β deposits, Lewy bodies accumulation, tau formation leading to neurofibrillary tangles. Impaired insulin signaling is directly associated with amyloid-β and α-synuclein deposition, as well as specific signaling cascades involved in neurodegenerative diseases. Insulin dysfunction may initiate various intracellular signaling cascades, including phosphoinositide 3-kinase (PI3K), c-Jun N-terminal kinases (JNK), and mitogen-activated protein kinase (MAPK). Neuronal death, inflammation, neuronal excitation, mitochondrial malfunction, and protein deposition are all influenced by insulin. Recent research has focused on GLP-1 receptor agonists as a potential therapeutic target. They increase glucose-dependent insulin secretion and are beneficial in neurodegenerative diseases by reducing oxidative stress and cytokine production. They reduce the deposition of abnormal proteins by crossing the blood-brain barrier. The purpose of this article is to discuss the role of insulin dysfunction in the pathogenesis of neurological diseases, specifically dementia. Additionally, we reviewed the therapeutic target (GLP-1) and its receptor activators as a possible treatment of dementia.

Agreement Between Automated and Manual MRI Volumetry in Alzheimer's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Automated magnetic resonance imaging (MRI) volumetry is a promising tool to evaluate regional brain volumes in dementia and especially Alzheimer's disease (AD).

PURPOSE

To compare automated methods and the gold standard manual segmentation in measuring regional brain volumes on MRI across healthy controls, patients with mild cognitive impairment, and patients with dementia due to AD.

STUDY TYPE

Systematic review and meta-analysis.

DATA SOURCES

MEDLINE, Embase, and PsycINFO were searched through October 2021.

FIELD STRENGTH

1.0 T, 1.5 T, or 3.0 T.

ASSESSMENT

Two review authors independently identified studies for inclusion and extracted data. Methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2).

STATISTICAL TESTS

Standardized mean differences (SMD; Hedges' g) were pooled using random-effects meta-analysis with robust variance estimation. Subgroup analyses were undertaken to explore potential sources of heterogeneity. Sensitivity analyses were conducted to examine the impact of the within-study correlation between effect estimates on the meta-analysis results.

RESULTS

Seventeen studies provided sufficient data to evaluate the hippocampus, lateral ventricles, and parahippocampal gyrus. The pooled SMD for the hippocampus, lateral ventricles, and parahippocampal gyrus were 0.22 (95% CI -0.50 to 0.93), 0.12 (95% CI -0.13 to 0.37), and -0.48 (95% CI -1.37 to 0.41), respectively. For the hippocampal data, subgroup analyses suggested that the pooled SMD was invariant across clinical diagnosis and field strength. Subgroup analyses could not be conducted on the lateral ventricles data and the parahippocampal gyrus data due to insufficient data. The results were robust to the selected within-study correlation value.

DATA CONCLUSION

While automated methods are generally comparable to manual segmentation for measuring hippocampal, lateral ventricle, and parahippocampal gyrus volumes, wide 95% CIs and large heterogeneity suggest that there is substantial uncontrolled variance. Thus, automated methods may be used to measure these regions in patients with AD but should be used with caution.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 3.

Regression-Based Normative Data for Independent and Cognitively Active Spanish Older Adults: Free and Cued Selective Reminding Test, Rey-Osterrieth Complex Figure Test and Judgement of Line Orientation

The aim of this work was to develop normative data for neuropsychological tests for the assessment of independent and cognitively active Spanish older adults over 55 years of age.

METHODS

regression-based normative data were calculated from a sample of 103 nondepressed independent community-dwelling adults aged 55 or older (66% women). The raw data for the Free and Cued Selective Reminding Test (FCSRT), the Rey-Osterrieth Complex Figure Test (ROCF) and the Judgement of Line Orientation Test (JLO) were regressed on age, sex and education. The model predicting the FCSRT delayed-recall (FCSRT-Del) scores also included the FCSRT immediate-recall (FCSRT-Imm) scores. The model predicting the ROCF immediate-recall (ROCF-Imm) scores included the ROCF copy-trial (ROCF-C) scores, and the model predicting the ROCF delayed-recall (ROCF-Del) scores included both the ROCF-C and the ROCF-Imm scores. In order to identify low scores, z-scores were used to determine the discrepancy between the observed and the predicted scores. The base rates of the low scores for both the SABIEX normative data and the published normative data obtained from the general population were compared.

RESULTS

the effects of the different sociodemographic variables (age, sex and education) varied throughout the neuropsychological measures. Despite finding similar proportions of low scores between the normative data sets, the agreement was irrelevant or only fair-to-good.

CONCLUSIONS

the normative data obtained from the general population might not be sensitive enough to identify low scores in cognitively active older adults, incorrectly classifying them as cognitively normal compared to the less active population.

Histopathological Analysis of Cerebrovascular Lesions Associated With Aging

Cerebrovascular disease (CVD) has been associated with cognitive impairment. Yet, our understanding of vascular contribution to cognitive decline has been limited by heterogeneity of definitions and assessment, as well as its occurrence in cognitively healthy aging. Therefore, we aimed to establish the natural progression of CVD associated with aging. We conducted a retrospective observational study of 63 cognitively healthy participants aged 19-84 years selected through the histological archives of the CHU de Québec. Assessment of CVD lesions was performed independently by 3 observers blinded to clinical data using the Vascular Cognitive Impairment Neuropathology Guidelines (VCING). We found moderate to almost perfect interobserver agreement for most regional CVD scores. Atherosclerosis (ρ = 0.758) and arteriolosclerosis (ρ = 0.708) showed the greatest significant association with age, followed by perivascular hemosiderin deposits (ρ = 0.432) and cerebral amyloid angiopathy (CAA; ρ = 0.392). Amyloid and tau pathologies were both associated with higher CVD load, but only CAA remained significantly associated with amyloid plaques after controlling for age. Altogether, these findings support the presence of multiple CVD lesions in the brains of cognitively healthy adults, the burden of which increases with age and can be quantified in a reproducible manner using standardized histological scales such as the VCING.

The identification of established modifiable mid-life risk factors for cardiovascular disease which contribute to cognitive decline: Korean Longitudinal Study of Aging (KLoSA)

INTRODUCTION

We explored how different chronic diseases, risk factors, and protective factors highly associated with cardiovascular diseases (CVD) are associated with dementia or Mild Cognitive Impairment (MCI) in Korean elders, with a focus on those that manifest in mid-life.

METHODS

A CVD-free cohort (n = 4289) from the Korean Longitudinal Study of Aging was selected to perform Cox mixed-effects proportional hazard regressions. Eighteen control variables with strong associations to CVD were chosen as explanatory variables, and Mini-Mental State Examination (MMSE) score cut-off for dementia and MCI were used as outcome variables.

RESULTS

The statistically significant (P < 0.05) adverse factors that contribute in developing dementia were age (aHR 1.07, 1.05-1.09), Centre for Epidemiological Studies Depression Scale (CESD-10) (aHR 1.17, 1.12-1.23), diagnosis with cerebrovascular disease (aHR 3.73, 1.81-7.66), living with diabetes (aHR 2.30, 1.22-4.35), and living with high blood pressure (HBP) (aHR 2.05, 1.09-3.87). In contrast, the statistically significant protective factors against developing dementia were current alcohol consumption (aHR 0.67, 0.46-0.99), higher educational attainment (aHR 0.36, 0.26-0.56), and regular exercise (aHR 0.37, 0.26-0.51). The factors with a statistically significant adverse association with progression to MCI were age (aHR 1.02, 1.01-1.03) and CESD-10 (aHR 1.17, 1.14-1.19). In contrast, the statistically significant protective factors against developing MCI were BMI (aHR 0.96, 0.94-0.98), higher educational attainment (aHR 0.33, 0.26-0.43), and regular exercise (aHR 0.83, 0.74-0.92).

CONCLUSION

In lieu of the protective factor of MCI and dementia, implementing regular exercise routine well before mid-life and cognitive decline is significant, with adjustments made for those suffering from health conditions, so they can continue exercising despite their morbidity. Further attention in diabetes care and management is needed for patients who already show decline in cognitive ability as it is likely that their MCI impacts their ability to manage their existing chronic conditions, which may adversely affect their cognitive ability furthermore.

Cerebrospinal fluid catecholamines in delirium and dementia

Dopamine and noradrenaline are functionally connected to delirium and have been targets for pharmacological interventions but the biochemical evidence to support this notion is limited. To study the CSF levels of dopamine, noradrenaline and the third catecholamine adrenaline in delirium and dementia, these were quantified in three patient cohorts: (i) cognitively normal elderly patients (n = 122); (ii) hip fracture patients with or without delirium and dementia (n = 118); and (iii) patients with delirium precipitated by another medical condition (medical delirium, n = 26). Delirium was assessed by the Confusion Assessment Method. The hip fracture cohort had higher CSF levels of noradrenaline and adrenaline than the two other cohorts (both P < 0.001). Within the hip fracture cohort those with delirium (n = 65) had lower CSF adrenaline and dopamine levels than those without delirium (n = 52, P = 0.03, P = 0.002). Similarly, the medical delirium patients had lower CSF dopamine levels than the cognitively normal elderly (P < 0.001). Age did not correlate with the CSF catecholamine levels. These findings with lower CSF dopamine levels in hip fracture- and medical delirium patients challenge the theory of dopamine excess in delirium and question use of antipsychotics in delirium. The use of alpha-2 agonists with the potential to reduce noradrenaline release needs further examination.

Global Cardiovascular Risk Profile and Cerebrovascular Abnormalities in Presymptomatic Individuals with CADASIL or Autosomal Dominant Alzheimer's Disease

BACKGROUND

Cardiovascular risk factors increase the risk of developing dementia, including Alzheimer's disease and vascular dementia.

OBJECTIVE

Studying individuals with autosomal dominant mutations leading to the early onset of dementia, this study examines the effect of the global cardiovascular risk profile on early cognitive and neuroimaging features of Alzheimer's disease and vascular dementia.

METHODS

We studied 85 non-demented and stroke-free individuals, including 20 subjects with Presenilin1 (PSEN1) E280A mutation leading to the early onset of autosomal dominant Alzheimer's disease (ADAD), 20 subjects with NOTCH3 mutations leading to cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) and to the early onset of vascular dementia, and 45 non-affected family members (non-carriers). All subjects underwent clinical and neuropsychological evaluations and an MRI. The global cardiovascular risk profile was estimated using the office-based Framingham Cardiovascular Risk Profile (FCRP) score.

RESULTS

In individuals with CADASIL, a higher FCRP score was associated with a reduced hippocampal volume (B = -0.06, p < 0.05) and an increased severity of cerebral microbleeds (B = 0.13, p < 0.001), lacunes (B = 0.30, p < 0.001), and perivascular space enlargement in the basal ganglia (B = 0.50, p < 0.05). There was no significant association between the FCRP score and neuroimaging measures in ADAD or non-carrier subjects. While the FCRP score was related to performance in executive function in non-carrier subjects (B = 0.06, p < 0.05), it was not significantly associated with cognitive performance in individuals with CADASIL or ADAD.

CONCLUSION

Our results suggest that individuals with CADASIL and other forms of vascular cognitive impairment might particularly benefit from early interventions aimed at controlling cardiovascular risks.

The impact of demographic, clinical, genetic, and imaging variables on tau PET status

PURPOSE

A substantial proportion of amyloid-β (Aβ)+ patients with clinically diagnosed Alzheimer's disease (AD) dementia and mild cognitive impairment (MCI) are tau PET-negative, while some clinically diagnosed non-AD neurodegenerative disorder (non-AD) patients or cognitively unimpaired (CU) subjects are tau PET-positive. We investigated which demographic, clinical, genetic, and imaging variables contributed to tau PET status.

METHODS

We included 2338 participants (430 Aβ+ AD dementia, 381 Aβ+ MCI, 370 non-AD, and 1157 CU) who underwent [18F]flortaucipir (n = 1944) or [18F]RO948 (n = 719) PET. Tau PET positivity was determined in the entorhinal cortex, temporal meta-ROI, and Braak V-VI regions using previously established cutoffs. We performed bivariate binary logistic regression models with tau PET status (positive/negative) as dependent variable and age, sex, APOEε4, Aβ status (only in CU and non-AD analyses), MMSE, global white matter hyperintensities (WMH), and AD-signature cortical thickness as predictors. Additionally, we performed multivariable binary logistic regression models to account for all other predictors in the same model.

RESULTS

Tau PET positivity in the temporal meta-ROI was 88.6% for AD dementia, 46.5% for MCI, 9.5% for non-AD, and 6.1% for CU. Among Aβ+ participants with AD dementia and MCI, lower age, MMSE score, and AD-signature cortical thickness showed the strongest associations with tau PET positivity. In non-AD and CU participants, presence of Aβ was the strongest predictor of a positive tau PET scan.

CONCLUSION

We identified several demographic, clinical, and neurobiological factors that are important to explain the variance in tau PET retention observed across the AD pathological continuum, non-AD neurodegenerative disorders, and cognitively unimpaired persons.

How can dementia and disability be prevented in older adults: where are we today and where are we going?

Ageing of the population, together with population growth, has brought along an ample increase in the number of older individuals living with dementia and disabilities. Dementia is the main cause of disability in old age, and promoting healthy brain ageing is considered as a key element in diminishing the burden of age-related disabilities. The World Health Organization recently launched the first risk reduction guidelines for cognitive impairment and dementia. According to recent estimates, approximately 40% of dementia cases worldwide could be attributable to 12 modifiable risk factors: low education; midlife hypertension and obesity; diabetes, smoking, excessive alcohol use, physical inactivity, depression, low social contact, hearing loss, traumatic brain injury and air pollution indicating clear prevention potential. Dementia and physical disability are closely linked with shared risk factors and possible shared underlying mechanisms supporting the possibility of integrated preventive interventions. FINGER trial was the first large randomized controlled trial indicating that multidomain lifestyle-based intervention can prevent cognitive and functional decline amongst at-risk older adults from the general population. Within the World-Wide FINGERS network, the multidomain FINGER concept is now tested and adapted worldwide proving evidence and tools for effective and easily implementable preventive strategies. Close collaboration between researchers, policymakers and healthcare practitioners, involvement of older adults and utilization of new technologies to support self-management is needed to facilitate the implementation of the research findings. In this scoping review, we present the current scientific evidence in the field of dementia and disability prevention and discuss future directions in the field.

Genetic Counselling Improves the Molecular Characterisation of Dementing Disorders

Dementing disorders are a complex group of neurodegenerative diseases characterised by different, but often overlapping, pathological pathways. Genetics have been largely associated with the development or the risk to develop dementing diseases. Recent advances in molecular technologies permit analyzing of several genes in a small time, but the interpretation analysis is complicated by several factors: the clinical complexity of neurodegenerative disorders, the frequency of co-morbidities, and the high phenotypic heterogeneity of genetic diseases. Genetic counselling supports the diagnostic path, providing an accurate familial and phenotypic characterisation of patients. In this review, we summarise neurodegenerative dementing disorders and their genetic determinants. Genetic variants and associated phenotypes will be divided into high and low impact, in order to reflect the pathologic continuum between multifactorial and mendelian genetic factors. Moreover, we report a molecular characterisation of genes associated with neurodegenerative disorders with cognitive impairment. In particular, the high frequency of rare coding genetic variants in dementing genes strongly supports the role of geneticists in both, clinical phenotype characterisation and interpretation of genotypic data. The smart application of exome analysis to dementia patients, with a pre-analytical selection on familial, clinical, and instrumental features, improves the diagnostic yield of genetic test, reduces time for diagnosis, and allows a rapid and personalised management of disease.

Pathobiological Subtypes of Alzheimer Disease

Alzheimer disease (AD), the most common form of dementia, is a heterogenous disorder with various pathobiological subtypes. In addition to the 4 major subtypes based on the distribution of tau pathology and brain atrophy (typical, limbic predominant, hippocampal sparing, and minimal atrophy [MA]), several other clinical variants showing distinct regional patterns of tau burden have been identified: nonamnestic, corticobasal syndromal, primary progressive aphasia, posterior cortical atrophy, behavioral/dysexecutive, and mild dementia variants. Among the subtypes, differences were found in age at onset, sex distribution, cognitive status, disease duration, APOE genotype, and biomarker levels. The patterns of key network destructions parallel the tau and atrophy patterns of the AD subgroups essentially. Interruption of key networks, in particular the default-mode network that is responsible for cognitive decline, is consistent in hetero-genous AD groups. AD pathology is often associated with co-pathologies: cerebrovascular lesions, Lewy pathology, and TDP-43 proteinopathies. These mixed pathologies essentially influence the clinical picture of AD and may accel-erate disease progression. Unraveling the heterogeneity among the AD spectrum entities is important for opening a window to pathogenic mechanisms affecting the brain and enabling precision medicine approaches as a basis for developing preventive and ultimately successful disease-modifying therapies for AD.

Multidomain Interventions to Prevent Cognitive Impairment, Alzheimer's Disease, and Dementia: From FINGER to World-Wide FINGERS

Alzheimer’s disease (AD) and dementia are a global public health priority, and prevention has been highlighted as a pivotal component in managing the dementia epidemic. Modifiable risk factors of dementia and AD include lifestyle-related factors, vascular and metabolic disorders, and psychosocial factors. Randomized controlled clinical trials (RCTs) are needed to clarify whether modifying such factors can prevent or postpone cognitive impairment and dementia in older adults. Given the complex, multifactorial, and heterogeneous nature of late-onset AD and dementia, interventions targeting several risk factors and mechanisms simultaneously may be required for optimal preventive effects. The Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) is the first large, long-term RCT to demonstrate that a multidomain lifestyle-based intervention ameliorating vascular and lifestyle-related risk factors can preserve cognitive functioning and reduce the risk of cognitive decline among older adults at increased risk of dementia. To investigate the multidomain intervention in other populations and diverse cultural and geographical settings, the World-Wide FINGERS (WW-FINGERS) network was recently launched (https://alz.org/wwfingers). Within this network, new FINGER-type trials with shared core methodology, but local culture and context-specific adaptations, will be conducted in several countries. The WW-FINGERS initiative facilitates international collaborations, provides a platform for testing multidomain strategies to prevent cognitive impairment and dementia, and aims at generating high-quality scientific evidence to support public health and clinical decision-making. Furthermore, the WW-FINGERS network can support the implementation of preventive strategies and translation of research findings into practice.

2021 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease (AD), including incidence and prevalence, mortality and morbidity, use and costs of care, and the overall impact on caregivers and society. The Special Report discusses the challenges of providing equitable health care for people with dementia in the United States. An estimated 6.2 million Americans age 65 and older are living with Alzheimer's dementia today. This number could grow to 13.8 million by 2060 barring the development of medical breakthroughs to prevent, slow or cure AD. Official death certificates recorded 121,499 deaths from AD in 2019, the latest year for which data are available, making Alzheimer's the sixth-leading cause of death in the United States and the fifth-leading cause of death among Americans age 65 and older. Between 2000 and 2019, deaths from stroke, heart disease and HIV decreased, whereas reported deaths from AD increased more than 145%. This trajectory of deaths from AD was likely exacerbated in 2020 by the COVID-19 pandemic. More than 11 million family members and other unpaid caregivers provided an estimated 15.3 billion hours of care to people with Alzheimer's or other dementias in 2020. These figures reflect a decline in the number of caregivers compared with a decade earlier, as well as an increase in the amount of care provided by each remaining caregiver. Unpaid dementia caregiving was valued at $256.7 billion in 2020. Its costs, however, extend to family caregivers' increased risk for emotional distress and negative mental and physical health outcomes - costs that have been aggravated by COVID-19. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are more than three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 23 times as great. Total payments in 2021 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $355 billion. Despite years of efforts to make health care more equitable in the United States, racial and ethnic disparities remain - both in terms of health disparities, which involve differences in the burden of illness, and health care disparities, which involve differences in the ability to use health care services. Blacks, Hispanics, Asian Americans and Native Americans continue to have a higher burden of illness and lower access to health care compared with Whites. Such disparities, which have become more apparent during COVID-19, extend to dementia care. Surveys commissioned by the Alzheimer's Association recently shed new light on the role of discrimination in dementia care, the varying levels of trust between racial and ethnic groups in medical research, and the differences between groups in their levels of concern about and awareness of Alzheimer's disease. These findings emphasize the need to increase racial and ethnic diversity in both the dementia care workforce and in Alzheimer's clinical trials.

Concomitant neurodegenerative pathologies contribute to the transition from mild cognitive impairment to dementia

INTRODUCTION

The aged brain frequently exhibits multiple pathologies, rather than a single hallmark pathology (pure pathology [PurP]), ranging from low/intermediate levels of additional pathology (LowP) to mixed severe pathology (mixed SevP). We investigated the frequency of PurP, LowP, and mixed SevP, and the impact of additional LowP on cognition.

METHODS

Data came from 670 cases from the Brains for Dementia research program. Cases were categorized into PurP, mixed SevP, or a main disease with additional LowP; 508 cases had a clinical dementia rating.

RESULTS

69.9% of cases had LowP, 22.7% had PurP, and 7.5% had mixed SevP. Additional LowP increased the likelihood of having mild dementia versus mild cognitive impairment (MCI) by almost 20-fold (odds ratio = 19.5).

DISCUSSION

Most aged individuals have multiple brain pathologies. The presence of one additional LowP can significantly worsen cognitive decline, increasing the risk of transitioning from MCI to dementia 20-fold. Multimorbidity should be considered in dementia research and clinical studies.

Brain arteriolosclerosis

Brain arteriolosclerosis (B-ASC), characterized by pathologic arteriolar wall thickening, is a common finding at autopsy in aged persons and is associated with cognitive impairment. Hypertension and diabetes are widely recognized as risk factors for B-ASC. Recent research indicates other and more complex risk factors and pathogenetic mechanisms. Here, we describe aspects of the unique architecture of brain arterioles, histomorphologic features of B-ASC, relevant neuroimaging findings, epidemiology and association with aging, established genetic risk factors, and the co-occurrence of B-ASC with other neuropathologic conditions such as Alzheimer's disease and limbic-predominant age-related TDP-43 encephalopathy (LATE). There may also be complex physiologic interactions between metabolic syndrome (e.g., hypertension and inflammation) and brain arteriolar pathology. Although there is no universally applied diagnostic methodology, several classification schemes and neuroimaging techniques are used to diagnose and categorize cerebral small vessel disease pathologies that include B-ASC, microinfarcts, microbleeds, lacunar infarcts, and cerebral amyloid angiopathy (CAA). In clinical-pathologic studies that factored in comorbid diseases, B-ASC was independently associated with impairments of global cognition, episodic memory, working memory, and perceptual speed, and has been linked to autonomic dysfunction and motor symptoms including parkinsonism. We conclude by discussing critical knowledge gaps related to B-ASC and suggest that there are probably subcategories of B-ASC that differ in pathogenesis. Observed in over 80% of autopsied individuals beyond 80 years of age, B-ASC is a complex and under-studied contributor to neurologic disability.

Reciprocal Incremental Value of 18F-FDG-PET and Cerebrospinal Fluid Biomarkers in Mild Cognitive Impairment Patients Suspected for Alzheimer's Disease and Inconclusive First Biomarker

BACKGROUND

In Alzheimer's disease (AD) diagnosis, both cerebrospinal fluid (CSF) biomarkers and FDG-PET sometimes give inconclusive results.

OBJECTIVE

To evaluate the incremental diagnostic value of FDG-PET over CSF biomarkers, and vice versa, in patients with mild cognitive impairment (MCI) and suspected AD, in which the first biomarker resulted inconclusive.

METHODS

A consecutive series of MCI patients was retrospectively selected from two Memory Clinics where, as per clinical routine, either the first biomarker choice is FDG-PET and CSF biomarkers are only used in patients with uninformative FDG-PET, or vice versa. We defined criteria of uncertainty in interpretation of FDG-PET and CSF biomarkers, according to current evidence. The final diagnosis was established according to clinical-neuropsychological follow-up of at least one year (mean 4.4±2.2).

RESULTS

When CSF was used as second biomarker after FDG-PET, 14 out of 36 (39%) received informative results. Among these 14 patients, 11 (79%) were correctly classified with respect to final diagnosis, thus with a relative incremental value of CSF over FDG-PET of 30.6%. When FDG-PET was used as second biomarker, 26 out of 39 (67%) received informative results. Among these 26 patients, 15 (58%) were correctly classified by FDG-PET with respect to final diagnosis, thus with a relative incremental value over CSF of 38.5%.

CONCLUSION

Our real-world data confirm the added values of FDG-PET (or CSF) in a diagnostic pathway where CSF (or FDG-PET) was used as first biomarkers in suspected AD. These findings should be replicated in larger studies with prospective enrolment according to a Phase III design.

Effects of Electronic Nicotine Delivery Systems and Cigarettes on Systemic Circulation and Blood-Brain Barrier: Implications for Cognitive Decline

Electronic nicotine delivery systems (often known as e-cigarettes) are a novel tobacco product with growing popularity, particularly among younger demographics. The implications for public health are twofold, as these products may represent a novel source of tobacco-associated disease but may also provide a harm reduction strategy for current tobacco users. There is increasing recognition that e-cigarettes impact vascular function across multiple organ systems. Herein, we provide a comparison of evidence regarding the role of e-cigarettes versus combustible tobacco in vascular disease and implications for blood-brain barrier dysfunction and cognitive decline. Multiple non-nicotinic components of tobacco smoke have been identified in e-cigarette aerosol, and their involvement in vascular disease is discussed. In addition, nicotine and nicotinic signaling may modulate peripheral immune and endothelial cell populations in a highly context-dependent manner. Direct preclinical evidence for electronic nicotine delivery system-associated neurovascular impairment is provided, and a model is proposed in which non-nicotinic elements exert a proinflammatory effect that is functionally antagonized by the presence of nicotine.

β-Amyloid and tau biomarkers and clinical phenotype in dementia with Lewy bodies

OBJECTIVE

In a multicenter cohort of probable dementia with Lewy bodies (DLB), we tested the hypothesis that β-amyloid and tau biomarker positivity increases with age, which is modified by APOE genotype and sex, and that there are isolated and synergistic associations with the clinical phenotype.

METHODS

We included 417 patients with DLB (age 45-93 years, 31% women). Positivity on β-amyloid (A+) and tau (T+) biomarkers was determined by CSF β-amyloid_1-42 and phosphorylated tau in the European cohort and by Pittsburgh compound B and AV-1451 PET in the Mayo Clinic cohort. Patients were stratified into 4 groups: A-T-, A+T-, A-T+, and A+T+.

RESULTS

A-T- was the largest group (39%), followed by A+T- (32%), A+T+ (15%), and A-T+ (13%). The percentage of A-T- decreased with age, and A+ and T+ increased with age in both women and men. A+ increased more in APOE ε4 carriers with age than in noncarriers. A+ was the main predictor of lower cognitive performance when considered together with T+. T+ was associated with a lower frequency of parkinsonism and probable REM sleep behavior disorder. There were no significant interactions between A+ and T+ in relation to the clinical phenotype.

CONCLUSIONS

Alzheimer disease pathologic changes are common in DLB and are associated with the clinical phenotype. β-Amyloid is associated with cognitive impairment, and tau pathology is associated with lower frequency of clinical features of DLB. These findings have important implications for diagnosis, prognosis, and disease monitoring, as well as for clinical trials targeting disease-specific proteins in DLB.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that in patients with probable DLB, β-amyloid is associated with lower cognitive performance and tau pathology is associated with lower frequency of clinical features of DLB.

Increased blood BACE1 activity as a potential common pathogenic factor of vascular dementia and late onset Alzheimer's disease

Late onset Alzheimer disease (LOAD) is traditionally considered as a separate disease from vascular dementia (VAD). However, growing evidence suggests that β-amyloid (Aβ) accumulation, that initiates LOAD-related neurodegeneration, is preceded by vascular events. Previous in vitro studies showed that β-secretase 1 (BACE1), the key-enzyme of amyloidogenesis, is upregulated by cerebrovascular insult; moreover, its activity is increased both in brain and serum of LOAD patients. We aimed to investigate whether BACE1 serum activity is altered also in dementias related, or not, to cerebrovascular disease. Thus, we evaluated serum BACE1 activity in a sample of individuals, including patients with LOAD (n. 175), VAD (n. 40), MIXED (LOAD/VAD) dementia (n. 123), other types of dementia (n. 56), and healthy Controls (n. 204). We found that BACE1 was significantly higher not only in LOAD (+ 30%), but also in VAD (+ 35%) and MIXED dementia (+ 22%) (p < 0.001 for all), but not in the other types of dementia (+ 10%). Diagnostic accuracy was 77% for LOAD, 83% for VAD, and 77% for MIXED dementia. In conclusion, we showed for the first time that the increase in peripheral BACE1 activity is a common feature of LOAD and VAD, thus underlying a further pathogenic link between these two forms of dementia.

Neuropathological assessment of the Alzheimer spectrum

Alzheimer disease (AD), the most common form of dementia globally, classically defined a clinicopathological entity, is a heterogenous disorder with various pathobiological subtypes, currently referred to as Alzheimer continuum. Its morphological hallmarks are extracellular parenchymal β-amyloid (amyloid plaques) and intraneuronal (tau aggregates forming neurofibrillary tangles) lesions accompanied by synaptic loss and vascular amyloid deposits, that are essential for the pathological diagnosis of AD. In addition to "classical" AD, several subtypes with characteristic regional patterns of tau pathology have been described that show distinct clinical features, differences in age, sex distribution, biomarker levels, and patterns of key network destructions responsible for cognitive decline. AD is a mixed proteinopathy (amyloid and tau), frequently associated with other age-related co-pathologies, such as cerebrovascular lesions, Lewy and TDP-43 pathologies, hippocampal sclerosis, or argyrophilic grain disease. These and other co-pathologies essentially influence the clinical picture of AD and may accelerate disease progression. The purpose of this review is to provide a critical overview of AD pathology, its defining pathological substrates, and the heterogeneity among the Alzheimer spectrum entities that may provide a broader diagnostic coverage of this devastating disorder as a basis for implementing precision medicine approaches and for ultimate development of successful disease-modifying drugs for AD.

Incremental Value of CSF Biomarkers in Clinically Diagnosed AD and Non-AD Dementia

Background: Cerebrospinal fluid (CSF) biomarkers are used to diagnose Alzheimer disease (AD), especially in atypical clinical presentations. No consensus currently exists regarding cut-off values. This study aimed, firstly, to define optimal cut-off values for CSF biomarkers, and secondly, to investigate the most relevant diagnostic strategy for AD based on CSF biomarker combinations.

Methods: A total of 380 patients were prospectively included: 140 with AD, 240 with various neurological diagnoses (non-AD). CSF biomarkers were measured using ELISA. Univariate and multivariate analyses were performed using random forest and logistic regression approaches.

Results: Univariate receiver operating curve curves analysis of T-Tau, P-Tau₁₈₁, Aβ₄₂, Aβ₄₀ concentrations, and Aβ₄₂/Aβ₄₀ ratio levels showed AD cut-off values of ≥355, ≥57, ≤706, ≥10,854, and ≤0.059 ng/L, respectively. Multivariate analysis using random forest and logistic regression found that the algorithm based on P-Tau₁₈₁, Aβ₄₂ concentrations and Aβ₄₂/Aβ₄₀ ratio yielded the best discrimination between AD and non-AD populations. The cross-validation technique of the final model showed a mean accuracy of 0.85 and a mean AUC of 0.89.

Conclusion: This study confirms that the Aβ₄₂/Aβ₄₀ ratio was more useful than the Aβ₄₀ concentration in discriminating AD from non-AD populations in daily practice. These results indicate that the Aβ₄₂/Aβ₄₀ ratio should be assessed in all cases, independently of Aβ₄₂ concentrations.

CSF total tau/α-synuclein ratio improved the diagnostic performance for Alzheimer's disease as an indicator of tau phosphorylation

Background

Recently, several studies suggested potential involvements of α-synuclein in Alzheimer’s disease (AD) pathophysiology. Higher concentrations of α-synuclein were reported in cerebrospinal fluid (CSF) of AD patients with a positive correlation towards CSF tau, indicating its possible role in AD. We analyzed the CSF biomarkers to verify whether α-synuclein could be an additional supported biomarker in AD diagnosis.

Methods

In this cross-sectional study, CSF samples of 71 early-onset AD, 34 late-onset AD, 11 mild cognitive impairment, 17 subjective cognitive decline, 45 Parkinson’s disease, and 32 healthy control (HC) were collected. CSF amyloid-β1-42 (A), total tau (N), and phosphorylated tau181 (T) were measured by commercial ELISA kits, and in-house ELISA kit was developed to quantify α-synuclein. The cognitive assessments and amyloid-PET imaging were also performed.

Results

CSF α-synuclein manifested a tendency to increase in AD and to decreased in Parkinson’s disease compared to HC. The equilibrium states of total tau and α-synuclein concentrations were changed significantly in AD, and the ratio of total tau/α-synuclein (N/αS) was dramatically increased in AD than HC. Remarkably, N/αS revealed a strong positive correlation with tau phosphorylation rate. Also, the combination of N/αS with amyloid-β1-42/phosphorylated tau181 ratio had the best diagnosis performance (AUC = 0.956, sensitivity = 96%, specificity = 87%). In concordance analysis, N/αS showed the higher diagnostic agreement with amyloid-β1-42 and amyloid-PET. Analysis of biomarker profiling with N/αS had distinctive characteristics and clustering of each group. Especially, among the group of suspected non-Alzheimer’s disease pathophysiology, all A−T+N+ patients with N/αS+ were reintegrated into AD.

Conclusions

The high correlation of α-synuclein with tau and the elevated N/αS in AD supported the involvement of α-synuclein in AD pathophysiology. Importantly, N/αS improved the diagnostic performance, confirming the needs of incorporating α-synuclein as a biomarker for neurodegenerative disorders. The incorporation of a biomarker group [N/αS] could contribute to provide better understanding and diagnosis of neurodegenerative disorders.

Cognitive impairment in Parkinson's disease is multifactorial: A neuropsychological study

BACKGROUND

In Parkinson's disease, mild cognitive impairment and dementia are associated with α-synuclein deposition and spread. However, coexistent Alzheimer's disease and cerebrovascular disease are common at autopsy, and may affect cognition. Our objective was to map cognitive impairment in Parkinson's disease to these different causes using clinical assessment.

METHODS

Neuropsychological testing was performed in a cross-sectional sample of cognitively impaired patients with Parkinson's disease. The pattern of deficits in varying cognitive domains was mapped to the presentations that typify different diseases. Data were analysed by an expert multidisciplinary panel, referencing diagnostic criteria, to reach a consensus diagnosis for the cognitive dysfunction.

RESULTS

There were 45 participants with Parkinson's disease and cognitive impairment, 73.3% male, mean age 69.1 years (SD 8.3). Twenty-seven (60.0%) had mild cognitive impairment, and 18 had dementia (40.0%). Cognitive impairment was primarily attributable to Lewy body disease alone in 19 of 45 patients (42.2%), to Lewy body disease plus Alzheimer's in 14 of 45 (31.1%), to Lewy body plus cerebrovascular disease in 6 of 45 (13.3%), and to Lewy body plus Alzheimer's and cerebrovascular disease in 1 of 45 (2.2%). The cognitive decline was not primarily Lewy-related in 5 of 45 patients (11.1%); in 4 of 45 (8.9%), it was primarily attributable to Alzheimer's disease, and 1 of 45 (2.2%) had behavioural-variant frontotemporal dementia.

CONCLUSION

Neuropsychological testing identifies distinct patterns of cognitive impairment in Parkinson's disease that provide clear pointers to comorbid disease processes, the most common being Alzheimer's disease. This approach may prove useful in clinical practice and has implications for clinical trials that target α-synuclein.

APOE ε4 genotype-dependent cerebrospinal fluid proteomic signatures in Alzheimer's disease

Background

Aggregation of amyloid β into plaques in the brain is one of the earliest pathological events in Alzheimer’s disease (AD). The exact pathophysiology leading to dementia is still uncertain, but the apolipoprotein E (APOE) ε4 genotype plays a major role. We aimed to identify the molecular pathways associated with amyloid β aggregation using cerebrospinal fluid (CSF) proteomics and to study the potential modifying effects of APOE ε4 genotype.

Methods

We tested 243 proteins and protein fragments in CSF comparing 193 subjects with AD across the cognitive spectrum (65% APOE ε4 carriers, average age 75 ± 7 years) against 60 controls with normal CSF amyloid β, normal cognition, and no APOE ε4 allele (average age 75 ± 6 years).

Results

One hundred twenty-nine proteins (53%) were associated with aggregated amyloid β. APOE ε4 carriers with AD showed altered concentrations of proteins involved in the complement pathway and glycolysis when cognition was normal and lower concentrations of proteins involved in synapse structure and function when cognitive impairment was moderately severe. APOE ε4 non-carriers with AD showed lower expression of proteins involved in synapse structure and function when cognition was normal and lower concentrations of proteins that were associated with complement and other inflammatory processes when cognitive impairment was mild. Repeating analyses for 114 proteins that were available in an independent EMIF-AD MBD dataset (n = 275) showed that 80% of the proteins showed group differences in a similar direction, but overall, 28% effects reached statistical significance (ranging between 6 and 87% depending on the disease stage and genotype), suggesting variable reproducibility.

Conclusions

These results imply that AD pathophysiology depends on APOE genotype and that treatment for AD may need to be tailored according to APOE genotype and severity of the cognitive impairment.

Genetic architecture of common non-Alzheimer's disease dementias

Frontotemporal dementia (FTD), dementia with Lewy bodies (DLB) and vascular dementia (VaD) are the most common forms of dementia after Alzheimer’s disease (AD). The heterogeneity of these disorders and/or the clinical overlap with other diseases hinder the study of their genetic components. Even though Mendelian dementias are rare, the study of these forms of disease can have a significant impact in the lives of patients and families and have successfully brought to the fore many of the genes currently known to be involved in FTD and VaD, starting to give us a glimpse of the molecular mechanisms underlying these phenotypes. More recently, genome-wide association studies have also pointed to disease risk-associated loci. This has been particularly important for DLB where familial forms of disease are very rarely described. In this review we systematically describe the Mendelian and risk genes involved in these non-AD dementias in an effort to contribute to a better understanding of their genetic architecture, find differences and commonalities between different dementia phenotypes, and uncover areas that would benefit from more intense research endeavors.

Transcranial Doppler could help to differentiate the types of dementia? A pilot study when CSF biomarkers are not available

Our objective was to find a mean flow velocity (MFV) cut-off point to differentiate between normal and cognitive impaired patients using Clinical Dementia Rating (CDR) as a comparison method. To evaluate MFV (in cm/s) and pulsatility index (PI) from the left middle cerebral artery (MCA) and basilar artery using transcranial Doppler in a pilot study from an outpatient cognition unit and compare with cognitively normal older adults (at the age of sixty or older) from the Geriatric Ambulatory of Fluminense Federal University. We hypothesized that there is a MFV and PI cut-off point to potentially distinguish between normal and impaired cognition. Sixty-one patients with cognitive decline, including 18 with amnestic mild cognitive impairment (aMCI), 31 with probable Alzheimer disease (AD), 12 with vascular dementia (VD), and 10 cognitively normal older adults were included in the study. Patients with dementia (both AD and VD, p < 0.01) and aMCI (p < 0.05) had lower MFV than the control group in the MCA (32.2 cm/s, 31.9 cm/s, and 36.6 cm/s, respectively) and dementia patients had higher PI compared to control (AD and VD, both p < 0.05). Basilar MFV showed to be no difference between the patients and the control group. A cut off value of 39.1 cm/s was found in a ROC curve (area under de curve value 0.85, 95% CI 0.75-0.95) for mean MCA MFV to be predictive of cognitive impairment (CDR ≥ 0.5). In this study, the values of MCA MFV below 39.1 cm/s were predictive of cognitive impairment according to CDR. TCD is an inexpensive method that could be used in a clinical scenario to help differentiate normal cognition from cognitive decline. Multicentric and longitudinal studies should be done to validate that.

Epidemiology of neurological diseases in older adults

Neurological diseases refer to the diseases that target the nervous system (brain, spine or nerves). They are the second leading cause of death, and the first cause of severe long-term disability in the world. The prevalence of most neurological diseases increases sharply with age, and age also modulates the impact of risk factors, clinical presentation and the natural course of these diseases. Longitudinal population-based studies provide useful insights for a better understanding of the specificities of neurological diseases in older adults by assessment of a wide range of risk factors. Rapid population aging, especially in low-income countries, presents challenges in terms of health and social care. A multidisciplinary approach is necessary to find solutions to tackle the burden of neurological diseases in older adults.

Cambridge Cognitive Examination and Hachinski Ischemic Score as predictors of MRI confirmed pathology in dementia: A cross-sectional study

AIMS AND BACKGROUND

Dementia is diagnosed through a combination of clinical assessment, cognitive assessment tools and neuroimaging. The aim of this retrospective, naturalistic study was to explore the association between the clinical assessment tools used in a memory clinic and the findings of Magnetic Resonance Imaging (MRI) scans in patients with dementia.

METHODS

Data were collected through routine clinical practice for all patients assessed at a memory assessment clinic in East Sussex, UK. Included patients had an MRI scan and received a formal diagnosis of dementia. Multinomial logistic regression was used to investigate the associations between atrophy on MRI with age, gender, Cambridge Cognitive Examination (CAMCOG) and Hachinski Ischemic Score (HIS). Ordinal logistic regression was used to study the associations between vascular findings on MRI with age, gender, CAMCOG and HIS. Because of the distribution of HIS scores a cut-off of 1 or greater was used in the regression analysis.

RESULTS

Male gender was associated with an increased likelihood of moderate atrophy (relative risk ratio (RRR) = 1.99, 95% confidence interval (CI) = 1.04-3.82), severe atrophy (RRR = 3.04, 95% CI = 1.38-6.68) and regional atrophy (RRR = 2.25, 95% CI = 1.26-4.00) on MRI. An increase of one point on the CAMCOG was associated with a decreased risk of regional atrophy (RRR = 0.98, 95% CI = 0.96-1.00) on MRI. There were no significant associations between age, or HIS, and atrophy on MRI. An increase in age of one year was associated with an increase in severity of vascular pathology reported on MRI (OR = 1.08, 95% CI = 1.05-1.12). Male gender was associated with reduced severity of vascular pathology reported on MRI (OR = 0.53, 95% CI = 0.36-0.78). There were no associations between CAMCOG, or HIS, and vascular pathology on MRI.

DISCUSSION

Our data show that CAMCOG was associated with MRI findings of regional atrophy and vascular pathology was greater in older patients. We highlight the importance of using a multi-modal approach to dementia diagnosis.

The Effect of Chronic Cerebral Hypoperfusion on Blood-Brain Barrier Permeability in a Transgenic Alzheimer's Disease Mouse Model (PS1V97L)

The blood-brain barrier (BBB) can restrict the therapeutic effects of Alzheimer's disease (AD) medications. While a large number of AD drug treatment trials targeting BBB dynamics have emerged, most have failed due to insufficient permeability. Furthermore, a subset of AD cases, which also feature chronic hypoperfusion are complicated by BBB deficits. We used a mouse model of AD with chronic hypoperfusion-transgenic mice (PS1V97L) with right common carotid artery ligation. In this model, we assessed how chronic cerebral hypoperfusion changed the pathophysiological processes that increase BBB permeability. Compared with control mice, AD mice with chronic hypoperfusion revealed significantly upregulated expression of the receptor for advanced glycation end products (RAGE) on the BBB. Upregulated RAGE caused increased accumulation of amyloid-β (Aβ) in the brain in these mice. Upregulation of RAGE (or binding to Aβ) can promote activation of the NF-κB pathway and enhance oxidative stress and increase the release of pro-inflammatory factors. These factors promoted the reduction of tight junction proteins between the endothelial cells in the BBB and increased its permeability. These findings suggest that the transporter RAGE dysregulation on the BBB initiates a series of pathophysiological processes which lead to increased BBB permeability. Taken together, we have shown that chronic hypoperfusion can serve to enhance and aggravate the BBB impairment in AD.

Summative Effects of Vascular Risk Factors on the Progression of Alzheimer Disease

OBJECTIVES

To investigate the summative effects of vascular risk factors (VRFs) on the progression of Alzheimer disease (AD).

DESIGN

Longitudinal follow-up cohort study.

SETTING

AD patients from two teaching hospitals in Taiwan with 3-year follow-ups.

PARTICIPANTS

A total of 330 AD patients with a mean age of 80.7 years, a mean Mini-Mental State Examination (MMSE) score 18.7, and a mean Clinical Dementia Rating Sum of Boxes (CDRSB) score of 6.9.

MEASUREMENTS

All patients completed a clinically functional assessment and a neuropsychological test battery at baseline and yearly follow-ups. The VRF burden was combined into a summative VRF index at baseline (ie, having one, two, or more VRFs); VRFs included coronary heart disease, cardiac arrhythmia, hypertension, cerebrovascular disease, diabetes mellitus, obesity, smoking, and physical inactivity. The generalized estimating equation (GEE) method was used to analyze the correlations between the VRFs and longitudinal MMSE and CDRSB changes.

RESULTS

The results of the GEE adjusted for age, years of education, sex, disease duration, baseline MMSE score, time, apolipoprotein E (APOE) ε4 carrier status, use of medications (acetylcholinesterase inhibitors or N-methyl-D-aspartate receptor antagonists), and hospitalization rates and showed that patients with more than three VRFs had more rapid cognitive decline than patients without VRFs (MMSE, P = .02; CDRSB, P = .001) as well as patients with three or fewer VRFs (MMSE, P = .009; CDRSB, P = .02). Subsequent analyses of APOE ε4 carriers with more than three VRFs also showed their more rapid cognitive decline compared with patients without VRFs (MMSE, P = .02; CDRSB, P = .001) and patients with three or fewer VRFs (MMSE, P = .009; CDRSB, P = .02), but no significant difference was found in APOE ε4 noncarriers.

CONCLUSION

Multiple VRFs have summative effects on the progression of AD, especially in APOE ε4 carriers. J Am Geriatr Soc 68:129-136, 2019.

Lifestyle interventions to prevent cognitive impairment, dementia and Alzheimer disease

Research into dementia prevention is of paramount importance if the dementia epidemic is to be halted. Observational studies have identified several potentially modifiable risk factors for dementia, including hypertension, dyslipidaemia and obesity at midlife, diabetes mellitus, smoking, physical inactivity, depression and low levels of education. Randomized clinical trials are needed that investigate whether interventions targeting these risk factors can reduce the risk of cognitive decline and dementia in elderly adults, but such trials are methodologically challenging. To date, most preventive interventions have been tested in small groups, have focused on a single lifestyle factor and have yielded negative or modest results. Given the multifactorial aetiology of dementia and late-onset Alzheimer disease, multidomain interventions that target several risk factors and mechanisms simultaneously might be necessary for an optimal preventive effect. In the past few years, three large multidomain trials (FINGER, MAPT and PreDIVA) have been completed. The FINGER trial showed that a multidomain lifestyle intervention can benefit cognition in elderly people with an elevated risk of dementia. The primary results from the other trials did not show a statistically significant benefit of preventive interventions, but additional analyses among participants at risk of dementia showed beneficial effects of intervention. Overall, results from these three trials suggest that targeting of preventive interventions to at-risk individuals is an effective strategy. This Review discusses the current knowledge of lifestyle-related risk factors and results from novel trials aiming to prevent cognitive decline and dementia. Global initiatives are presented, including the World Wide FINGERS network, which aims to harmonize studies on dementia prevention, generate high-quality scientific evidence and promote its implementation.

A Particularly Tragic Case of Possible Alzheimer's Disease, that of Marshal Pétain

After World War I and more particularly in June 1940, the prestige of French Marshal Philippe Pétain, considered as the winning general the battle of Verdun, was very high. He became President of Council while the French army was unable to stop the German offensives. But five years later he was sentenced to death for high treason. By rereading his bibliography from a medical perspective, it is possible to find multiple suggestive events and to affirm a posteriori Pétain suffered from a neurodegenerative disorder, whose first signs appeared in the 1930s, suggestive of Alzheimer's disease, which had an impact on French politics. The modern medical knowledge of this disease casts a new light on the behavior of Petain during the last war.