Identification of VaD and AD prodromes: the Cache County Study

Predicting the onset of Alzheimer's disease and related dementia using Electronic Health Records: Findings from the Cache County Study on Memory in Aging (1995-2008)

INTRODUCTION

Clinical notes, biomarkers, and neuroimaging have been proven valuable in dementia prediction models. Whether commonly available structured clinical data can predict dementia is an emerging area of research. We aimed to predict Alzheimer's disease (AD) and Alzheimer's disease related dementias (ADRD) in a well-phenotyped, population-based cohort using a machine learning approach. Methods Administrative healthcare data (k = 163 diagnostic features), in addition to Census/vital record sociodemographic data (k = 6 features), were linked to the Cache County Study (CCS, 1995-2008). Results Among successfully linked UPDB-CCS participants (n = 4206), 522 (12.4%) had incident AD/ADRD as per the CCS "gold standard" assessments. Random Forest models, with a 1-year prediction window, achieved the best performance with an Area Under the Curve (AUC) of 0.67. Accuracy declined for dementia subtypes: AD/ADRD (AUC = 0.65); ADRD (AUC = 0.49). DISCUSSION Commonly available structured clinical data (without labs, notes, or prescription information) demonstrate modest ability to predict AD/ADRD, corroborated by prior research.

Neuropsychological differential diagnosis of Alzheimer's disease and vascular dementia: a systematic review with meta-regressions

Introduction

Diagnostic classification systems and guidelines posit distinguishing patterns of impairment in Alzheimer's (AD) and vascular dementia (VaD). In our study, we aim to identify which diagnostic instruments distinguish them.

Methods

We searched PubMed and PsychInfo for empirical studies published until December 2020, which investigated differences in cognitive, behavioral, psychiatric, and functional measures in patients older than 64 years and reported information on VaD subtype, age, education, dementia severity, and proportion of women. We systematically reviewed these studies and conducted Bayesian hierarchical meta-regressions to quantify the evidence for differences using the Bayes factor (BF). The risk of bias was assessed using the Newcastle-Ottawa-Scale and funnel plots.

Results

We identified 122 studies with 17,850 AD and 5,247 VaD patients. Methodological limitations of the included studies are low comparability of patient groups and an untransparent patient selection process. In the digit span backward task, AD patients were nine times more probable (BF = 9.38) to outperform VaD patients (β g = 0.33, 95% ETI = 0.12, 0.52). In the phonemic fluency task, AD patients outperformed subcortical VaD (sVaD) patients (β g = 0.51, 95% ETI = 0.22, 0.77, BF = 42.36). VaD patients, in contrast, outperformed AD patients in verbal (β g = -0.61, 95% ETI = -0.97, -0.26, BF = 22.71) and visual (β g = -0.85, 95% ETI = -1.29, -0.32, BF = 13.67) delayed recall. We found the greatest difference in verbal memory, showing that sVaD patients outperform AD patients (β g = -0.64, 95% ETI = -0.88, -0.36, BF = 72.97). Finally, AD patients performed worse than sVaD patients in recognition memory tasks (β g = -0.76, 95% ETI = -1.26, -0.26, BF = 11.50).

Conclusion

Our findings show inferior performance of AD in episodic memory and superior performance in working memory. We found little support for other differences proposed by diagnostic systems and diagnostic guidelines. The utility of cognitive, behavioral, psychiatric, and functional measures in differential diagnosis is limited and should be complemented by other information. Finally, we identify research areas and avenues, which could significantly improve the diagnostic value of cognitive measures.

Normative Data for the Logical Memory Subtest of the Wechsler Memory Scale-IV in Middle-Aged and Elderly Korean People

OBJECTIVE

The purpose of this study is to identify the demographic variables that are affecting performances on the Logical Memory (LM) subtest included in the Korean version of the Wechsler Memory Scale (WMS)-IV and to provide normative data on the LM subtest for the middle-age and elderly Korean people.

METHODS

The participants were 435 non-demented adults aging from 50 to 90 and with the educational level ranging from 0 to 21 years.

RESULTS

Age and education were found to be significantly associated with performance on the LM subtest, while gender effect was not statistically significant. Therefore, we stratified the norm blocks by age and education. Age was divided into three groups: 50-59, 60-74, and 75-90 years. Education was stratified into three groups: 0-8 years, 9-12 years, and 13 years or more.

CONCLUSION

The normative data provided in the current study are expected to be useful in clinical and research settings to detect or define subtle changes in episodic memory in Korean adults and elderly, and can also be used for cross-cultural comparison of verbal episodic memory performance among elderly populations using different languages.

A T1 and DTI fused 3D corpus callosum analysis in MCI subjects with high and low cardiovascular risk profile

Understanding the extent to which vascular disease and its risk factors are associated with prodromal dementia, notably Alzheimer's disease (AD), may enhance predictive accuracy as well as guide early interventions. One promising avenue to determine this relationship consists of looking for reliable and sensitive in-vivo imaging methods capable of characterizing the subtle brain alterations before the clinical manifestations. However, little is known from the imaging perspective about how risk factors such as vascular disease influence AD progression. Here, for the first time, we apply an innovative T1 and DTI fusion analysis of 3D corpus callosum (CC) on mild cognitive impairment (MCI) populations with different levels of vascular profile, aiming to de-couple the vascular factor in the prodromal AD stage. Our new fusion method successfully increases the detection power for differentiating MCI subjects with high from low vascular risk profiles, as well as from healthy controls. MCI subjects with high and low vascular risk profiles showed differed alteration patterns in the anterior CC, which may help to elucidate the inter-wired relationship between MCI and vascular risk factors.

Impact of aerobic exercise on neurobehavioral outcomes

Numerous studies have examined the relationship between physical activity and cognitive function, demonstrating that greater physical activity is associated with lower incidence of cognitive impairment in later life. Due to an increasingly large number of older adults at risk for cognitive impairment, the relationship between physical activity and cognition has garnered increasing public health relevance and multiple randomized trials have demonstrated that exercise interventions among sedentary adults improve cognitive performance in multiple domains of function. This article will examine the relationship between physical activity and cognitive function by reviewing several different areas of literature, including the prevalence of cognitive impairment, assessment methods, observational studies examining physical activity and cognition, and intervention studies. The present review is intended to provide a historical tutorial of existing literature linking physical activity, exercise, and cognitive function among both healthy and clinical populations.

Can lifestyle modification improve neurocognition? Rationale and design of the ENLIGHTEN clinical trial

BACKGROUND

Risk factors for cardiovascular disease (CVD) not only increase the risk for clinical CVD events, but also are associated with a cascade of neurophysiologic and neuroanatomic changes that increase the risk of cognitive impairment and dementia. Although epidemiological studies have shown that exercise and diet are associated with lower CVD risk and reduced incidence of dementia, no randomized controlled trial (RCT) has examined the independent effects of exercise and diet on neurocognitive function among individuals at risk for dementia. The ENLIGHTEN trial is a RCT of patients with CVD risk factors who also are characterized by subjective cognitive complaints and objective evidence of neurocognitive impairment without dementia (CIND) STUDY DESIGN: A 2 by 2 design will examine the independent and combined effects of diet and exercise on neurocognition. 160 participants diagnosed with CIND will be randomly assigned to 6 months of aerobic exercise, the DASH diet, or a combination of both exercise and diet; a (control) group will receive health education but otherwise will maintain their usual dietary and activity habits. Participants will complete comprehensive assessments of neurocognitive functioning along with biomarkers of CVD risk including measures of blood pressure, glucose, endothelial function, and arterial stiffness.

CONCLUSION

The ENLIGHTEN trial will (a) evaluate the effectiveness of aerobic exercise and the DASH diet in improving neurocognitive functioning in CIND patients with CVD risk factors; (b) examine possible mechanisms by which exercise and diet improve neurocognition; and (c) consider potential moderators of treatment, including subclinical CVD.

A homopolymer polymorphism in the TOMM40 gene contributes to cognitive performance in aging

INTRODUCTION

A highly polymorphic T homopolymer was recently found to be associated with late-onset Alzheimer's disease risk and age of onset.

OBJECTIVE

To explore the effects of the polymorphic polyT tract (rs10524523, referred as '523') on cognitive performance in cognitively healthy elderly individuals.

METHODS

One hundred eighty-one participants were recruited from local independent-living retirement communities. Informed consent was obtained, and participants completed demographic questionnaires, a conventional paper-and-pencil neuropsychological battery, and the computerized Cambridge Neuropsychological Test Automated Battery (CANTAB). Saliva samples were collected for determination of the TOMM40 '523' (S, L, VL) and the apolipoprotein E (APOE) (ɛ2, 3, 4) genotypes. From the initial sample of 181 individuals, 127 were eligible for the association analysis. Participants were divided into three groups based on '523' genotypes (S/S, S/L-S/VL, and L/L-L/VL-VL/VL). Generalized linear models were used to evaluate the association between the '523' genotypes and neuropsychological test performance. Analyses were adjusted for age, sex, education, depression, and APOE ɛ4 status. A planned subanalysis was undertaken to evaluate the association between '523' genotypes and test performance in a sample restricted to APOE ɛ3 homozygotes.

RESULTS

The S homozygotes performed better, although not significantly, than the S/L-S/VL and the VL/L-L/VL-VL/VL genotype groups on measures associated with memory (CANTAB Paired Associates Learning, Verbal Recognition Memory free recall) and executive function (CANTAB measures of Intra-Extra Dimensional Set Shift). Follow-up analysis of APOE ɛ3 homozygotes only showed that the S/S group performed significantly better than the S/VL group on measures of episodic memory (CANTAB Paired Associates Learning and Verbal Recognition Memory free recall), attention (CANTAB Rapid Visual Information Processing latency), and executive function (Digit Symbol Substitution). The S/S group performed marginally better than the VL/VL group on Intra-Extra Dimensional Set Shift. None of the associations remained significant after applying a Bonferroni correction for multiple testing.

CONCLUSIONS

Results suggest important APOE-independent associations between the TOMM40 '523' polymorphism and specific cognitive domains of memory and executive control that are preferentially affected in early-stage Alzheimer's disease.

Verbal fluency and awareness of functional deficits in early-stage dementia

Assessment of activities of daily living is an important element in the diagnosis of dementia, with research suggesting a link between functional ability and cognition. We investigated the relationship between self- and informant ratings of instrumental activities of daily living (iADL) and verbal executive functioning in early-stage dementia. A total of 96 people with early-stage Alzheimer's disease or vascular or mixed dementia and their carers completed the Functional Activities Questionnaire; people with dementia also completed a test of letter fluency. Letter fluency was associated with self-ratings of iADL, while informant ratings of iADL were associated with the age and Mini-Mental State Examination score of the person with dementia. Self-ratings of perceived functioning suggested significantly less impairment than informant ratings. Those with impaired letter fluency rated themselves as having greater difficulties in iADLs than those who performed better. People with early-stage dementia vary in their subjective level of awareness of their iADL functioning, and difficulties with language production may contribute to better awareness of iADL impairments.

Epidemiology of cognitive aging and Alzheimer's disease: contributions of the cache county utah study of memory, health and aging

Epidemiological studies of Alzheimer's disease (AD) provide insights into changing public health trends and their contribution to disease incidence. The current chapter considers how the population-based approach has contributed to our understanding of lifetime exposures that contribute to later disease risk and may act to modify onset of symptoms. We focus on the findings from a recent survey of an exceptionally long-lived population, the Cache County Utah Study of Memory, Health, and Aging. This study is confined to a single geographic population has allowed estimation of the genetic and environmental influences on AD expression across the expected human lifespan of 95+ years. Given the emphasis of this text on the behavioral neurosciences of aging, we highlight within the current chapter the particular contributions of this population-based study to the neuropsychology of aging and AD. We also discuss hypotheses generated from this survey with respect to factors that may either accelerate or delay symptom onset in AD and the conditions that appear to be associated with successful cognitive aging.

Validity of the montreal cognitive assessment (MoCA) as a screening test for mild cognitive impairment (MCI) in a cardiovascular population

While rates of mild cognitive impairment (MCI) are relatively high in populations with cardiovascular diseases and risk factors, screening tests for MCI have not been evaluated in this patient group. This study investigated the sensitivity and specificity of the Montreal Cognitive Assessment (MoCA) tool for detecting MCI in 110 patients (mean age 67.9 + 11.7 years; 60% female) recruited from hospital cardiovascular outpatient clinics. Mean MoCA performance was relatively low (22.8 + 3.8) in this group, with 72.1% of participants scoring below the recommended cutoff for cognitive impairment (<26). The presence of MCI was determined using the Neuropsychological Assessment Battery Screening Module (NAB-SM). Both amnestic MCI and multiple-domain MCI were identified. The optimum MoCA cutoff for detecting MCI in this group was <24. At this cutoff, the MoCA's sensitivity for detecting amnestic MCI was 100% and for multiple-domain MCI it was 83.3%. Specificity rates for amnestic MCI and multiple-domain MCI were 50.0% and 52% respectively. The poor specificity of the MoCA suggests that it will have limited value as a screening test for MCI in settings where the overall prevalence of MCI is low.

Cognitive impairment predicts functional capacity in dementia-free patients with cardiovascular disease

BACKGROUND AND RESEARCH OBJECTIVE

A high proportion of elderly people with cardiovascular diseases and risk factors have mild forms of cognitive impairment, the functional impact of which is poorly understood. The aim of this study was to determine whether subtle cognitive impairment contributes to limitations in instrumental activities of daily living in this group and whether this association is independent of physical comorbidity and other potentially confounding factors.

SUBJECTS AND METHODS

Two hundred and nineteen nondemented patients were recruited from cardiovascular and diabetic hospital outpatient clinics. Functional dependence was assessed using the self-report version of the instrumental activities of daily living scale. Cognitive ability was assessed using the Montreal Cognitive Assessment (MoCA). Demographic and clinical information was collected via interview and a review of hospital records. Standard logistic regression was performed to identify factors independently associated with functional status.

RESULTS

Five variables (sex, cardiovascular disease burden, non-cardiovascular disease burden, cognitive status, and age) were independently associated with an increased likelihood of requiring assistance with 1 or more everyday activities. The likelihood of needing assistance increased 2.05 times (95% confidence interval [CI], 1.59-2.79) for each additional cardiovascular diagnosis present and 1.12 times (95% CI, 1.01-1.27) for every point lower on MoCA. Thus, in comparison to a person with a perfect MoCA score, a person who scored in the cognitively impaired range (<23) was 7.7 (CI, 7.07-8.89) times more likely to report that he/she required assistance with an everyday activity.

CONCLUSION

Cognitive impairments appear to reduce the ability to independently carry out routine daily tasks in patients with cardiovascular diseases and risk factors. Cognition should therefore be considered along with physical symptoms when assessing and responding to the support needs of this group.

Modifying dementia risk and trajectories of cognitive decline in aging: the Cache County Memory Study

The Cache County Study of Memory, Health, and Aging, more commonly referred to as the "Cache County Memory Study (CCMS)" is a longitudinal investigation of aging and Alzheimer's disease (AD) based in an exceptionally long-lived population residing in northern Utah. The study begun in 1994 has followed an initial cohort of 5,092 older individuals (many over age 84) and has examined the development of cognitive impairment and dementia in relation to genetic and environmental antecedents. This article summarizes the major contributions of the CCMS towards the understanding of mild cognitive disorders and AD across the lifespan, underscoring the role of common health exposures in modifying dementia risk and trajectories of cognitive change. The study now in its fourth wave of ascertainment illustrates the role of population-based approaches in informing testable models of cognitive aging and Alzheimer's disease.

Beyond mild cognitive impairment: vascular cognitive impairment, no dementia (VCIND)

Identifying the causes of dementia is important in the search for effective preventative and treatment strategies. The concept of mild cognitive impairment (MCI), as prodromal dementia, has been useful but remains controversial since in population-based studies it appears to be a limited predictor of progression to dementia. Recognising the relative contribution of neurodegenerative and vascular causes, as well as their interrelationship, may enhance predictive accuracy. The concept of vascular cognitive impairment (VCI) has been introduced to describe the spectrum of cognitive change related to vascular causes from early cognitive decline to dementia. A recent review of this concept highlighted the need for diagnostic criteria that encompass the full range of the VCI construct. However, very little is known regarding the mildest stage of VCI, generally termed 'vascular cognitive impairment, no dementia' (VCIND). Whether mild cognitive change in the context of neurodegenerative pathologies is distinct from that in the context of cerebrovascular diseases is not known. This is key to the definition of VCIND and whether it is possible to identify this state. Distinguishing between vascular (that is, VCIND) and non-vascular (that is, MCI) cognitive disorders and determining how well each might predict dementia may not be possible due to the overlap in pathologies observed in the older population. Here, we review the concept of VCIND in an effort to identify recent developments and areas of controversy in nosology and the application of VCIND for screening individuals at increased risk of dementia secondary to vascular disease and its risk factors.

Neuropsychological performance in advanced age: influences of demographic factors and Apolipoprotein E: findings from the Cache County Memory Study

The Cache County Study of Memory in Aging (CCMS) is an epidemiological study of Alzheimer's disease (AD), mild cognitive disorders, and aging in a population of exceptionally long-lived individuals (7th to 11th decade). Observation of population members without dementia provides an opportunity for establishing the range of normal neurocognitive performance in a representative sample of the very old. We examined neurocognitive performance of the normal participants undergoing full clinical evaluations (n = 507) and we tested the potential modifying effects of apolipoprotein E (APOE) genotype, a known genetic risk factor for the later development of AD. The results indicate that advanced age and low education are related to lower test scores across nearly all of the neurocognitive measures. Gender and APOE epsilon4 both had negligible and inconsistent influences, affecting only isolated measures of memory and expressive speech (in case of gender). The gender and APOE effects disappeared once age and education were controlled. The study of this exceptionally long-lived population provides useful normative information regarding the broad range of "normal" cognition seen in advanced age. Among elderly without dementia or other cognitive impairment, APOE does not appear to exert any major effects on cognition once other demographic influences are controlled.