High rates of undiagnosed vascular cognitive impairment among American Indian veterans

Epidemiology and prevalence of dementia and Alzheimer's disease in American Indians: Data from the Strong Heart Study

INTRODUCTION

Accurate epidemiologic estimates for dementia are lacking for American Indians, despite substantive social and health disparities.

METHODS

The Strong Heart Study, a population-based cohort of 11 American Indian tribes, conducted detailed cognitive testing and examinations over two visits approximately 7 years apart. An expert panel reviewed case materials for consensus adjudication of cognitive status (intact; mild cognitive impairment [MCI]; dementia; other impaired/not MCI) and probable etiology (Alzheimer's disease [AD], vascular bain injury [VBI], traumatic brain injury [TBI], other).

RESULTS

American Indians aged 70-95 years had 54% cognitive impairment including 10% dementia. VBI and AD were primary etiology approximately equal proportions (>40%). Apolipoprotein (APO) Eε4 carriers were more common among those with dementia (p = 0.040). Plasma pTau, glial fibrillary acidic protein (GFAP), and neurofilament light chain (NfL) were higher among those with cognitive impairment, but not amyloid beta (Aβ). Cognitive intact had mean 3MSE 92.2 (SD 6.4) and mean Montreal Cognitive Assessment (MoCA) score of 21.3 (SD 3.2).

DISCUSSION

This is the first population-based study to estimate the prevalence of vascular and Alzheimer's dementias in a population-based study of American Indians.

HIGHLIGHTS

The Strong Heart Study is a population-based cohort of American Indian tribes, conducted over 30+ years and three US geographic regions (Northern Plains, Southern Plains, Southwest). Our teams conducted detailed cognitive testing, neurological examination, and brain imaging over two visits approximately 7 years apart. An expert panel reviewed collected materials for consensus-based adjudication of cognitive status (intact; MCI; dementia; other impaired/not MCI) and probable underlying etiology (AD; VBI; TBI; other). In this cohort of American Indians aged 70-95, 54% were adjudicated with cognitive impairment, including approximately 35% MCI and 10% dementia. These data expand on prior reports from studies using electronic health records, which had suggested prevalence, and incidence of dementia in American Indians to be more comparable to the majority population or non-Hispanic White individuals, perhaps due to latent case undercounts in clinical settings. Vascular and neurodegenerative injuries were approximately equally responsible for cognitive impairment, suggesting that reduction of cardiovascular disease is needed for primary prevention. Traumatic injury was more prevalent than in other populations, and common among those in the "other/not MCI" cognitive impairment category. Mean scores for common dementia screening instruments-even among those adjudicated as unimpaired-were relatively low compared to other populations (mean unimpaired 3MSE 92.2, SD 6.4; mean unimpaired MoCA 21.3, SD 3.2), suggesting the need for cultural and environmental adaptation of common screening and evaluation instruments.

Risk, protective, and biomarkers of dementia in Indigenous peoples: A systematic review

INTRODUCTION

Dementia is an emergent health priority for Indigenous peoples worldwide, yet little is known about disease drivers and protective factors.

METHODS

Database searches were conducted in March 2022 to identify original publications on risk, protective, genetic, neuroradiological, and biological factors related to dementia and cognitive impairment involving Indigenous peoples.

RESULTS

Modifiable risk factors featured across multiple studies include childhood adversity, hearing loss, low education attainment, unskilled work history, stroke, head injury, epilepsy, diabetes, hypertension, hyperlipidemia, depression, low BMI, poor mobility, and continence issues. Non-modifiable risk factors included increasing age, sex, and genetic polymorphisms. Education, ex-smoking, physical and social activity, and engagement with cultural or religious practices were highlighted as potential protective factors. There is a paucity of research on dementia biomarkers involving Indigenous peoples.

DISCUSSION

Greater understanding of modifiable factors and biomarkers of dementia can assist in strength-based models to promote healthy ageing and cognition for Indigenous peoples.

The Role of Methionine-Rich Diet in Unhealthy Cerebrovascular and Brain Aging: Mechanisms and Implications for Cognitive Impairment

As aging societies in the western world face a growing prevalence of vascular cognitive impairment and Alzheimer's disease (AD), understanding their underlying causes and associated risk factors becomes increasingly critical. A salient concern in the western dietary context is the high consumption of methionine-rich foods such as red meat. The present review delves into the impact of this methionine-heavy diet and the resultant hyperhomocysteinemia on accelerated cerebrovascular and brain aging, emphasizing their potential roles in cognitive impairment. Through a comprehensive exploration of existing evidence, a link between high methionine intake and hyperhomocysteinemia and oxidative stress, mitochondrial dysfunction, inflammation, and accelerated epigenetic aging is drawn. Moreover, the microvascular determinants of cognitive deterioration, including endothelial dysfunction, reduced cerebral blood flow, microvascular rarefaction, impaired neurovascular coupling, and blood-brain barrier (BBB) disruption, are explored. The mechanisms by which excessive methionine consumption and hyperhomocysteinemia might drive cerebromicrovascular and brain aging processes are elucidated. By presenting an intricate understanding of the relationships among methionine-rich diets, hyperhomocysteinemia, cerebrovascular and brain aging, and cognitive impairment, avenues for future research and potential therapeutic interventions are suggested.

The Burden of Dementia Spectrum Disorders and Associated Comorbid and Demographic Features

Dementia spectrum disorders (DSDs) are a major cause of mortality and disability worldwide. DSDs encompass a large group of medical conditions that all ultimately lead to major functional and cognitive decline and disability. Demographic and comorbid conditions that are associated with DSDs have significant prognostic and preventive implications. In this article, we will discuss the global and regional burden of DSDs and cover key demographic and clinical conditions linked with DSDs. In the absence of disease-modifying treatments, the role of primary prevention has become more prominent. Implementation of preventive measures requires an understanding of predisposing and exacerbating factors.

Educational and Clinical Associations With Longitudinal Cognitive Function and Brain Imaging in American Indians: The Strong Heart Study

BACKGROUND AND OBJECTIVES

Little is known about incidence of vascular and Alzheimer dementias in American Indians.

METHODS

We conducted a large, heterogeneous, population-based, longitudinal cohort study of brain aging in community-dwelling American Indians aged 64-95 years from 11 tribes across 3 states, with neurologic examinations, 1.5T MRI, and extensive cognitive testing. Visit 1 in 2010-2013 (n = 817) and visit 2 in 2017-2019 (n = 403) included all willing, surviving participants. Standardized cognitive tests at both visits included Modified Mini-Mental Status Examination (MMSE), Wechsler Adult Intelligence Scale digit symbol coding (WAIS), Controlled Oral Word Association (COWA), and California Verbal Learning Test short form (CVLT). Test materials added at follow-up included Wide Range Achievement (reading) Test (WRAT) and National Alzheimer Coordinating Center Uniform Data Set cognitive battery (v3 form C2), including Montreal Cognitive Assessment (MoCA). MRI neuroradiologists coded infarcts, hemorrhages, white matter hyperintensities, sulcal atrophy, and ventricle enlargement.

RESULTS

The mean time between examinations was 6.7 years (SD 1.1, range 3.8-9.1 years). Years of formal education had modest correlation with WRAT reading score (r = 0.45). Prevalence and incidence (respectively) of infarcts were 32% and 12.8/1,000 person-years (PYs) hemorrhages 6% and 4.4/1000 PY worsening sulci 74% and 19.0/1000 PY worsening ventricle 79% and 30.1/1000 PY worsening leukoaraiosis 44% and 26.1/1000 PY. Linear losses per year in cognitive scores were 0.6% MMSE, 1.2% WAIS, 0.6% COWA, and 2.2% CVLT. The mean MoCA scores were 18.9 (SD 4.3).

DISCUSSION

These are the first data on longitudinal cognitive and imaging changes in American Indians and first reports of Alzheimer disease-related features. The mean scores in MoCA were similar or lower than standard cutoffs used to diagnose dementia in other racial/ethnic groups, suggesting that standardized cognitive tests may not perform well in this population. Test validation, adaptation, and score adjustment are warranted. Years of education were a poor proxy for premorbid function, suggesting novel methods for cognitive score contextualization is also needed in this population. Evaluation of selective survival suggests attrition from death, and frailty should be accounted for in causal analyses. Overall, these data represent a unique opportunity to examine neurology topics of critical importance to an understudied population.

Volume, scope, and consideration of ethical issues in Indigenous cognitive impairment and dementia research: A systematic scoping review of studies published between 2000-2021

INTRODUCTION

High quality research involving Indigenous people with cognitive impairment and dementia is critical for informing evidence-based policy and practice. We examined the volume, scope and ethical considerations of research related to dementia with Indigenous populations globally from January 2000-December 2021.

METHODS

Studies were included if they were published in English from 2000 to 2021 and provided original data that focused on cognitive impairment or dementia in any Indigenous population.

RESULTS

The search yielded 13,009 papers of which, 76 met inclusion criteria. The overall number of papers increased over time. Studies were mostly conducted in Australia with Aboriginal and Torres Strait Islander people (n = 30; 39%). Twenty-six papers directly involved Indigenous participants with cognitive impairment or dementia. Of these studies, ethics approval was commonly required from two or more committees (n = 23, 88.5%). Ethical and legal governance frameworks were rarely discussed.

DISCUSSION

There is a clear need for further robust studies examining cognitive impairment and dementia with Indigenous populations. Future research should consider the ethical aspects of involving Indigenous participants with cognitive impairment in research.

Vascular cognitive impairment and dementia: An early career researcher perspective

The field of vascular contributions to cognitive impairment and dementia (VCID) is evolving rapidly. Research in VCID encompasses topics aiming to understand, prevent, and treat the detrimental effects of vascular disease burden in the human brain. In this perspective piece, early career researchers (ECRs) in the field provide an overview of VCID, discuss past and present efforts, and highlight priorities for future research. We emphasize the following critical points as the field progresses: (a) consolidate existing neuroimaging and fluid biomarkers, and establish their utility for pharmacological and non-pharmacological interventions; (b) develop new biomarkers, and new non-clinical models that better recapitulate vascular pathologies; (c) amplify access to emerging biomarker and imaging techniques; (d) validate findings from previous investigations in diverse populations, including those at higher risk of cognitive impairment (e.g., Black, Hispanic, and Indigenous populations); and (e) conduct randomized controlled trials within diverse populations with well-characterized vascular pathologies emphasizing clinically meaningful outcomes.

Prenatal cigarette smoke exposure slightly alters neurobehavioral development in neonatal rats: Implications for developmental origins of health and disease (DoHAD)

Numerous studies indicate that smoking during pregnancy exerts harmful effects on fetal brain development. The aim of this study was to determine the influence of maternal smoking during pregnancy on the early physical and neurobehavioral development of newborn rats. Wistar rats were subjected to whole-body smoke exposure for 2 × 40 min daily from the day of mating until day of delivery. For this treatment, a manual closed-chamber smoking system and 4 research cigarettes per occasion were used. After delivery the offspring were tested daily for somatic growth, maturation of facial characteristics and neurobehavioral development until three weeks of age. Motor coordination tests were performed at 3 and 4 weeks of age. We found that prenatal cigarette smoke exposure did not alter weight gain or motor coordination. Critical physical reflexes indicative of neurobehavioral development (eyelid reflex, ear unfolding) appeared significantly later in pups prenatally exposed to smoke as compared to the control group. Prenatal smoke exposure also resulted in a delayed appearance of reflexes indicating neural maturity, including hind limb grasping and forelimb placing reflexes. In conclusion, clinically relevant prenatal exposure to cigarette smoke results in slightly altered neurobehavioral development in rat pups. These findings suggest that chronic exposure of pregnant mothers to cigarette smoke (including passive smoking) results in persisting alterations in the developing brain, which may have long-lasting consequences supporting the concept of developmental origins of health and disease (DoHAD).