Geographically overlapping Alzheimer's disease registries: comparisons and implications

Impact of Recruitment Methods in Subjective Cognitive Decline

BACKGROUND

Recruitment methods can determine sample characteristics in mild cognitive impairment and Alzheimer's disease dementia, but little is known about its influence in subjective cognitive decline (SCD).

OBJECTIVE

To determine the influence of two types of recruitment methods in the characteristics of individuals with SCD.

METHODS

We select and compare clinical and neuropsychological features, and frequency of APOE ɛ4 allele of 326 subjects with SCD from two cohorts: Open House Initiative (OHI) versus Memory Unit (MU). A logistic regression analysis (LRA), using gender and years of education as covariates, was used to examine the neuropsychological variables.

RESULTS

The OHI sample were mostly women (75.9% versus 64.5%, p < 0.05), with higher educational level (12.15 [3.71] versus 10.70 [3.80] years, p = 0.001), and more family history of dementia (138 [62.7%] versus 44 [41.5%], p < 0.001) than the MU sample. Also, the OHI sample showed better overall neuropsychological performance than the MU sample, and after a LRA, this trend continued in automatic response inhibition capacity, abstract reasoning, and recognition memory. We did not find differences in age, depression history, and/or APOE ɛ4 allele frequency.

CONCLUSION

SCD subjects showed different demographic and neuropsychological characteristics depending on the recruitment method, which should be taken into account in the design of research studies with this target population.

Dementia registries around the globe and their applications: A systematic review

Patient registries are valuable tools helping to address significant challenges in research, care, and policy. Registries, well embedded in many fields of medicine and public health, are relatively new in dementia. This systematic review presents the current situation in regards to dementia registries worldwide. We identified 31 dementia registries operating on an international, national, or local level between 1986 and 2016. More than half of the registries aimed to conduct or facilitate research, including preclinical research registries and registries recruiting research volunteers. Other dementia registries collected epidemiological or quality of care data. We present evidence of practical and economic outcomes of registries for research, clinical practice and policy, and recommendations for future development. Global harmonization of recruitment methods and minimum data would facilitate international comparisons. Registries provide a positive return on investment; their establishment and maintenance require ongoing support by government, policy makers, research funding bodies, clinicians, and individuals with dementia and their caregivers.

Older Rural- and Urban-Dwelling Appalachian Adults With Mild Cognitive Impairment

PURPOSE

Mild cognitive impairment (MCI) is a well-recognized risk state for Alzheimer's disease and other dementias. MCI is rapidly increasing among older adults in general and has not yet been examined in older adults within the Appalachian region. Our objective was to compare MCI symptom severity among older rural and urban Appalachian adults with MCI at an initial neuropsychological testing visit.

METHODS

A cross-sectional, descriptive study of older Appalachian adults with MCI was conducted using data from the National Alzheimer's Coordinating Center Uniform Data Set. Symptom severity was conceptualized as neuropsychological composite scores across 4 cognitive domains and Clinical Dementia Rating-Sum of Boxes (CDR-SOB) score. For group comparisons, MANCOVA was used for cognitive domains and ANCOVA for CDR-SOB.

RESULTS

The sample (N = 289) was about half male (54.3%), predominantly white (91.7%), and living with others (83.5%), with a mean (±SD) 74.6 ± 6.2 years of age and 15.4 ± 3.0 years of education. Rural and urban groups differed significantly in years since onset of cognitive symptoms (2.98 ± 1.91 in rural and 3.89 ± 2.70 in urban adults, t[260] = -2.23, P = .03), but they did not differ across sociodemographic features or comorbid conditions. Rural and urban participants were similar across the 4 cognitive domains and CDR-SOB (P ≥ .05).

DISCUSSION

No differences were found between rural and urban Appalachian residents on MCI symptom severity. However, urban residents reported a longer time lapse from symptom identification to diagnosis than their rural counterparts. Future studies using more representative population samples of Appalachian and non-Appalachian adults will provide an important next step to identifying disparate cognitive health outcomes in this traditionally underserved region.

Importance of home study visit capacity in dementia studies

INTRODUCTION

The importance of home research study visit capacity in Alzheimer's disease (AD) studies is unknown.

METHODS

All evaluations are from the prospective Adult Changes in Thought study. Based on analyses of factors associated with volunteering for a new in-clinic initiative, we analyzed AD risk factors and the relevance of neuropathologic findings for dementia comparing all data including home visits, and in-clinic data only. We performed bootstrapping to determine whether differences were greater than expected by chance.

RESULTS

Of the 1781 people enrolled during 1994-1996 with ≥1 follow-up, 1369 (77%) had in-clinic data, covering 61% of follow-up time. In-clinic data resulted in excluding 76% of incident dementia and AD cases. AD risk factors and the relevance of neuropathologic findings for dementia were both different with in-clinic data.

DISCUSSION

Limiting data collection in AD studies to research clinics alone likely reduces power and also can lead to erroneous inferences.

Cerebral cortical Aβ42 and PHF-τ in 325 consecutive brain autopsies stratified by diagnosis, location, and APOE

We used a novel approach to molecular quantification in standard fixed and embedded tissue to measure amyloid β 42 (Aβ(42)) and paired helical filament-τ (PHF-τ) in frontal, temporal, and parietal cortices from 325 consecutive brain autopsies collected as part of a population-based study of brain aging and incident dementia in the Seattle area. We observed significant effects of APOE ε4 on Aβ(42) levels in both diagnostic groups by disease stage and region. In contrast, we did not observe a significant effect of APOE ε4 on PHF-τ levels by disease stage in any region. Levels of Aβ(42) and PHF-τ in cerebral cortex were correlated more strongly in the Dementia group, and these measures had independent explanatory power for dementia beyond those of standard neuropathologic indices. Associations between Lewy body disease and Aβ(42) or PHF-τ levels and between Aβ(42) levels and microvascular brain injury suggested that these comorbid diseases enhanced the penetrance of Alzheimer disease. Our novel approach brings additional insights into the molecular pathogenesis of common causes of dementia and may serve as a platform for future studies pursuing associations between molecular changes in Alzheimer disease and genetic or environmental risk.

Comorbidity in dementia: update of an ongoing autopsy study

OBJECTIVES

To examine systemic and central nervous system (CNS) comorbidities of individuals with dementia evaluated during general autopsy.

DESIGN

Retrospective cohort study.

SETTING

A large tertiary academic medical center in Los Angeles, California.

PARTICIPANTS

Individuals with clinically and neuropathologically diagnosed dementia who received complete autopsies (n = 86) and individuals with dementia who received partial (brain only) autopsies (n = 132).

MEASUREMENTS

Information on cause of death and systemic and CNS comorbidities was obtained from autopsy reports and clinical information as available from the medical records. Findings were tabulated with respect to type of dementia, semiquantitative assessment of the severity of cerebral amyloid angiopathy, semiquantitative assessment of the severity of cerebrovascular disease, and evidence of ischemic damage in the brain.

RESULTS

Of 218 subjects with dementia, 175 (80.3%) had Alzheimer's disease alone or in combination with other lesions that might contribute to cognitive impairment, such as cerebrovascular disease and diffuse Lewy body disease (DLBD), 14 (6.4%) had frontotemporal dementia, and seven (3.2%) had isolated DLBD. The most common cause of death in participants with dementia was pneumonia (n = 57, 66.3%), followed by cardiovascular disease (n = 14, 16.3%). Eighteen subjects (20.9%) had lung disease, and 16 (18.6%) had evidence of an old or recent myocardial infarction. Clinically undiagnosed neoplasms included colonic adenocarcinoma, metastatic pulmonary neuroendocrine carcinoma, meningioma, and Schwannoma.

CONCLUSION

Significant comorbidities were discovered at autopsy in individuals with dementia. Understanding the causes of death and associated comorbidities in individuals with various subtypes of dementia is important in the assessment of end-of-life care in these individuals.

Comparison of imaging biomarkers in the Alzheimer Disease Neuroimaging Initiative and the Mayo Clinic Study of Aging

OBJECTIVE

To determine whether magnetic resonance imaging measurements observed in the Alzheimer Disease Neuroimaging Initiative (ADNI) convenience sample differ from those observed in the Mayo Clinic Study of Aging (MCSA) population-based sample.

DESIGN

Comparison of 2 samples.

SETTING

Fifty-nine recruiting sites for the ADNI in the United States and Canada and the MCSA, a population-based cohort in Olmsted County, Minnesota.

PATIENTS

Cognitively normal subjects and amnestic subjects with mild cognitive impairment were selected from the ADNI convenience cohort and MCSA population-based cohort. A simple random sample of subjects from both cohorts in the same age range was selected, and a second sample applied matching for age, sex, educational level, apolipoprotein E genotype, and Mini-Mental State Examination score.

MAIN OUTCOME MEASURES

Baseline hippocampal volumes and annual percentage of decline in hippocampal volume.

RESULTS

In the population-based sample, MCSA subjects were older, had less education, performed worse on the Mini-Mental State Examination, and had a family history of Alzheimer disease less often than did ADNI subjects. Baseline hippocampal volumes were larger in ADNI compared with MCSA cognitively normal subjects in the random sample, although no differences were observed after matching. Rates of decline in hippocampal volume were greater in the ADNI compared with the MCSA for cognitively normal subjects and those with amnestic mild cognitive impairment, even after matching.

CONCLUSIONS

Rates of decline in hippocampal volume suggest that ADNI subjects have a more aggressive brain pathologic process than MCSA subjects and hence may not be representative of the general population. These findings have implications for treatment trials that use ADNI-like recruitment mechanisms and for studies validating new diagnostic criteria for Alzheimer disease in its various stages.

Passive case-finding for Alzheimer's disease and dementia in two U.S. communities

Passive surveillance for disease is a public health approach that relies on documentation available within existing health records for the region or community being studied. Its two primary advantages over active case-finding are the lower cost of research and the lower burden on the population under study. The effectiveness of passive case-finding depends on the comprehensiveness of the healthcare coverage in a given community and the adequacy of the available medical records. The Rochester Epidemiology Project has permitted dementia case detection for Olmsted County, Minnesota, using a medical records-linkage system. These data were compared with case ascertainment using direct assessment of individuals in an epidemiological study of the same community. At the Group Health Research Institute, investigators compared dementia and Alzheimer's disease cases detected using an electronic medical record database search with those identified by a parallel active case-finding study. In this article, the advantages and disadvantages of passive case-finding were discussed, and the following conclusion was drawn: the purpose of the study being conducted should determine the case-finding approach that is to be used.

Visual hallucinations in dementia: a prospective community-based study with autopsy

OBJECTIVE

Several studies have demonstrated that specific neuropathologic features may be associated with the presence of visual hallucinations in dementia patients, but the clinical usefulness of these studies has been limited because their subjects were selected on the basis of neuropathologic findings rather than clinical presentations. This study seeks to investigate the demographic, clinical, and neuropathologic features of community-based dementia subjects with and without visual hallucations.

DESIGN

A prospective examination of the clinical and neuropathologic correlates of visual hallucinations in community-based dementia subjects.

PARTICIPANTS

One hundred forty-eight subjects with sufficient clinical and neuropathologic data from a community-based incident dementia autopsy case series.

RESULTS

Subjects were classified according to the presence or absence of visual hallucinations and subjects with visual hallucinations (N = 27) were younger at intake and more likely to exhibit agitation, delusions, and apathy than subjects without visual hallucinations (N = 121). Subjects with visual hallucinations were also more likely than subjects without visual hallucinations to have Lewy-related pathology (LRP) (78% versus 45%). In addition, a higher frequency of visual hallucinations was observed in subjects with neocortical LRP than subjects with limbic-, amygdala-, or brainstem-predominant LRP. Although Alzheimer disease with concomitant LRP was the most common neuropathologic subtype in the visual hallucinations-positive group (59%), the frequency of subjects with Alzheimer disease pathology did not differ significantly between those with and without visual hallucinations (74% versus 62%).

CONCLUSIONS

Subjects with visual hallucinations were more likely to have concomitant postural and gait disturbance, additional neuropsychiatric symptoms, and neocortical LRP than subjects without visual hallucinations. Visual hallucinations accompanying dementia have distinct clinical and neuropathologic characteristics that are important for prognosis and clinical management.

Consortium to Establish a Registry for Alzheimer's Disease (CERAD): the first twenty years

The Consortium to Establish a Registry for Alzheimer's Disease (CERAD) was funded by the National Institute on Aging in 1986 to develop standardized, validated measures for the assessment of Alzheimer's disease (AD). The present report describes the measures that CERAD developed during its first decade and their continued use in their original and translated forms. These measures include clinical, neuropsychological, neuropathologic, and behavioral assessments of AD and also assessment of family history and parkinsonism in AD. An approach to evaluating neuroimages did not meet the standards desired. Further evaluations that could not be completed because of lack of funding (but where some materials are available) include evaluation of very severe AD and of service use and need by patient and caregiver. The information that was developed in the U.S. and abroad permits standardized assessment of AD in clinical practice, facilitates epidemiologic studies, and provides information valuable for individual and public health planning. CERAD materials and data remain available for those wishing to use them.

Prevalence of cognitive impairment without dementia in the United States

BACKGROUND

Cognitive impairment without dementia is associated with increased risk for disability, increased health care costs, and progression to dementia. There are no population-based prevalence estimates of this condition in the United States.

OBJECTIVE

To estimate the prevalence of cognitive impairment without dementia in the United States and determine longitudinal cognitive and mortality outcomes.

DESIGN

Longitudinal study from July 2001 to March 2005.

SETTING

In-home assessment for cognitive impairment.

PARTICIPANTS

Participants in ADAMS (Aging, Demographics, and Memory Study) who were age 71 years or older drawn from the nationally representative HRS (Health and Retirement Study). Of 1770 selected individuals, 856 completed initial assessment, and of 241 selected individuals, 180 completed 16- to 18-month follow-up assessment.

MEASUREMENTS

Assessments, including neuropsychological testing, neurologic examination, and clinical and medical history, were used to assign a diagnosis of normal cognition, cognitive impairment without dementia, or dementia. National prevalence rates were estimated by using a population-weighted sample.

RESULTS

In 2002, an estimated 5.4 million people (22.2%) in the United States age 71 years or older had cognitive impairment without dementia. Prominent subtypes included prodromal Alzheimer disease (8.2%) and cerebrovascular disease (5.7%). Among participants who completed follow-up assessments, 11.7% with cognitive impairment without dementia progressed to dementia annually, whereas those with subtypes of prodromal Alzheimer disease and stroke progressed at annual rates of 17% to 20%. The annual death rate was 8% among those with cognitive impairment without dementia and almost 15% among those with cognitive impairment due to medical conditions.

LIMITATIONS

Only 56% of the nondeceased target sample completed the initial assessment. Population sampling weights were derived to adjust for at least some of the potential bias due to nonresponse and attrition.

CONCLUSION

Cognitive impairment without dementia is more prevalent in the United States than dementia, and its subtypes vary in prevalence and outcomes.

Empiric refinement of the pathologic assessment of Lewy-related pathology in the dementia patient

Lewy-related pathology (LRP) is a common pathologic finding at autopsy in dementia patients. Recently criteria for categorizing types of LRP in dementia patients were published, though these criteria have yet to be systematically applied to large dementia samples. We examined a large (n = 208) referral-based autopsy sample for LRP, and applied the published criteria for LRP categorization to these cases. We found almost half (49%) of LRP positive cases from this sample were not classifiable. However, modifying the published criteria by reducing the number of regions requiring examination, allowing more variability in LRP severity scores within specific brain regions, and adding an amygdala predominant category permitted classification of 97% of LRP positive cases from the referral-based sample. Application of the modified criteria to an unrelated community-based autopsy sample (n = 226) allowed classification of 96% of LRP positive cases. Modest modifications in the published criteria permit a significantly greater number of dementia cases with LRP to be classified. In addition, this modification allows for more limited sampling of brain regions for classification of LRP. We propose that these modified criteria for the categorization of LRP be utilized in patients with a history of dementia.

Predicting lewy body pathology in a community-based sample with clinical diagnosis of Alzheimer's disease

Accurate antemortem prediction of Lewy body pathology in patients with dementia is problematic. This study generates a model that better predicts Lewy body pathology in community-based patients with clinical Alzheimer's disease. Lewy body pathology was detected in 80 of 152 participants (52.6%) with an initial diagnosis of probable Alzheimer's disease. In a stepwise logistic regression model, female gender, lower education, being married, bradykinesia, hallucinations, and absence of irritability predicted the greatest likelihood of Lewy body pathology. The predictive model correctly diagnosed Lewy body pathology with an estimated sensitivity of 75%, specificity of 68%, and accuracy of 72%; the area under the receiver operating characteristic curve was 0.75. In a community-based autopsy sample, this predictive model confirmed parkinsonism and hallucinations as important predictors of Lewy body pathology in patients with clinical Alzheimer's disease. The model also identified other demographic and clinical characteristics that might enhance the prediction of Lewy body pathology.

Evaluation of selection bias in an incident-based dementia autopsy case series

Neuropathological (np) relative frequency estimates of dementia may be biased if the autopsied subjects are not representative of all dementia subjects within a target population. We identified characteristics that differed between autopsied and non-autopsied subjects from an incident-based dementia case series and compared autopsy-based estimates of the relative frequency of np diagnoses before and after adjusting for potential selection bias. Clinically demented subjects who were autopsied (n = 206), had died but were not autopsied (n = 271), were still alive (n = 71), or had dropped out of the study (n = 82) were included. Compared with non-autopsied subjects, autopsied subjects were more likely to be Caucasian, educated beyond high school, and married. They also tended to have a lower baseline Mini-Mental State Examination score and were more likely to have a clinical diagnosis of Alzheimer disease (AD) than non-autopsied subjects. Neuropathological AD with Lewy bodies (LB) had the largest crude relative frequency estimate at 38% of the autopsy sample, followed by 25% for AD with vascular lesions, 13% for pure AD, 13% for LB (with or without vascular lesions), and 8% for pure vascular pathologies. Adjustment for potential sources of selection bias had little effect on relative frequency estimates, suggesting that np diagnoses in the autopsied subjects provide reasonable dementia relative frequency estimates among all clinically demented cases in this series.

Effect of vascular lesions on cognition in Alzheimer's disease: a community-based study

OBJECTIVES

To investigate whether clinical and neuropathological differences exist between Alzheimer's disease (AD) cases with and without vascular lesions neuropathologically diagnosed using Consortium to Establish a Registry for Alzheimer's Disease (CERAD) criteria.

DESIGN

Descriptive observational study.

SETTING

A community-based registry that identified incident dementia cases.

PARTICIPANTS

Of the 124 subjects with available clinical and neuropathological assessments, 30 had AD lesions alone, and 18 had AD with vascular lesions. Patients with other neuropathological findings were excluded.

MEASUREMENTS

Dependent measures included demographic, clinical, and neuropathological characteristics. Neuropathological diagnoses were made using the CERAD criteria and Braak and Braak staging.

RESULTS

Of the 124 autopsied cases, 85 cases were diagnosed with neuropathological AD. Of these, 30 had pathology consistent with "pure" AD, whereas 18 had AD pathology with significant vascular lesions (AD/V). There were no differences in age, sex, or education between groups. AD/V cases had higher baseline and final Mini-Mental State Examination (MMSE) scores than pure AD cases, but after adjusting for education, differences in MMSE scores were not statistically significant. The AD/V group had significantly lower Braak staging than the pure AD group, after adjusting for education and final MMSE scores.

CONCLUSION

In this comparison study of AD cases with and without vascular lesions, AD/V cases had less severe AD pathology than those with AD alone, indicating that cerebrovascular disease likely contributes to the severity of cognitive impairment in those with AD. Controlling for vascular risk factors in patients with AD may have a significant effect on severity of dementia.

Clinico-neuropathological correlation of Alzheimer's disease in a community-based case series

OBJECTIVES

Most clinico-neuropathological correlative studies of Alzheimer's Disease (AD) are based on research cohorts that are not necessarily generalizable to patients seen in the general medical community. In this study, we examine the accuracy of the criteria used in diagnosing AD in a community-based case series of patients with memory complaints.

DESIGN AND PARTICIPANTS

Clinical and neuropathological diagnoses were obtained from 134 patients evaluated for dementia who subsequently underwent autopsy.

SETTING

Subjects who exhibited new symptoms of dementia and were enrolled in the University of Washington/Group Health Cooperative Alzheimer's Disease Patient Registry were eligible for this study.

MEASUREMENTS

Clinico-pathological correlation was performed using NINCDS-ADRDA (National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association) and CERAD (Consortium to Establish a Registry for Alzheimer's Disease) criteria.

RESULTS

Ninety-five of the 134 cases studied met CERAD neuropathological criteria for AD. The sensitivity of NINCDS-ADRDA "probable AD" was 83% (diagnosing AD correctly) and overall clinical diagnostic accuracy was 75%. However, there was a high rate of additional neuropathological findings. Only 34 of the 94 cases had pure AD on neuropathology, whereas the remainder frequently had coexisting vascular or Parkinson's disease lesions.

CONCLUSIONS

This study of a large series of community-based incident dementia cases provides a way of judging the adequacy of currently available clinical diagnostic criteria. It also shows that co-existing neuropathological findings are common in community-based AD.

Alzheimer's disease symptom severity in blacks and whites

OBJECTIVE

In order to determine whether there are racial differences in Alzheimer's Disease (AD) symptom severity and vascular comorbidities, we compared African-American (black) and Caucasian (white) patients with AD from similar socioeconomic backgrounds at the time the disease was first recognized.

DESIGN

Cross-sectional observational study from a population-based dementia registry.

PARTICIPANTS

Patients were enrolled from an HMO base population of 23,000 persons more than age 60 in Seattle, Washington. This study examines 453 subjects with probable AD (38 blacks (mean age 76.5, SD 6.4), and 415 whites (mean age 79.7, SD 6.7)).

MEASUREMENTS

Measured were patient demographics, age at onset of AD, AD symptom duration, Mini-Mental State Exam (MMSE) score, Blessed Dementia Rating Scale, presence of psychiatric symptoms, and vascular comorbidities.

RESULTS

Blacks had significantly lower mean cognitive scores (MMSE = 17.2, SD 5.6) compared with whites (MMSE = 20.2, SD 5.2, unpaired t test P < .01). The significant racial difference in MMSE scores persisted after controlling for education, duration of AD symptoms, age, and ADL impairment. Blacks and whites did not differ significantly regarding gender distribution, education level, income, or percent with early age of onset of AD. No statistically significant race-related differences were found in impairments in activities of daily living or symptoms of paranoia, hallucinations, or agitation. Blacks had significantly higher rates of hypertension (56%) compared with whites (34%) (Fisher's exact test, P = .013), but the rates of stroke and ischemic heart disease were similar.

CONCLUSIONS

Despite uniform detection methods and controlling for reported duration of dementia symptoms, measured cognitive impairment is significantly more severe when AD is recognized in blacks compared with whites. The significantly higher prevalence of hypertension among black AD cases was not associated with excess cerebrovascular disease comorbidity. This study highlights a need for normative measurements of cognitive function in minority AD groups in order to distinguish differential cognitive symptom severity from possible measurement bias.

Impact of sample selection on APOE epsilon 4 allele frequency: a comparison of two Alzheimer's disease samples

OBJECTIVE

In a highly selected sample of unrelated Alzheimer's disease (AD) patients, we found that the APOE epsilon 4 allele frequency was higher than previously reported. Differing selection and ascertainment criteria may lead to these differences. To address this possibility, we compared the epsilon 4 allele frequency in two samples of AD patients selected from the same geographical area.

SETTING AND PARTICIPANTS

Cases (n = 55) and controls (n = 99) from a research clinic-based sample were compared with subjects (n = 537) from a community-based AD patient sample. The samples consisted of unrelated cases who met NINCDS/ADRDA criteria for probable AD.

DESIGN AND MEASUREMENTS

Clinical characteristics and APOE genotype data were obtained from AD cases and controls from both samples.

RESULTS

Frequency of APOE epsilon 4 allele in the research cases compared with the community cases (0.45 vs 0.36) was nearly significant. We compared demographic and clinical characteristics that might account for this difference and found that the research cases were younger, had an earlier age of onset, and had more advanced disease than the community cases. After onset age was controlled, there was no overall difference between epsilon 4 allele frequency of the two samples.

CONCLUSIONS

We found that the epsilon 4 allele frequency tended to be higher in the research AD sample compared the community-based sample. The two samples differed in several demographic and clinical characteristics. We conclude that research-based samples may lead to enrollment of younger patients with more severe disease who have higher APOE epsilon 4 allele load. This potential selection bias must be considered in the interpretation of studies of APOE allele frequency.