The Relationship of Hypertension in the Elderly to AD, Vascular Dementia, and Cognitive Function

Background: Hypertension at the age of 45 to 50 years may predispose to AD later in life. It is not known whether hypertension after age 65 years also contributes to AD risk, and its effect on cognitive function is also not fully understood. Methods: Data were analyzed from 1,259 Medicare recipients free of dementia in a longitudinal study covering a 7-year period (1991 to 1998). The effect of hypertension was first examined in relationship to the risk for incident AD and then to incident vascular dementia (VaD) using Cox proportional hazards models. Changes in performance over time on tasks of memory, language, and visuospatial/cognitive function were compared in those with and without hypertension using generalized estimating equations. Results: Of the 1,259 subjects, 731 (58.1%) had a history of hypertension associated with diabetes, stroke, and heart disease. A history of hypertension was not associated with an increased risk for AD (rate ratio [RR] 0.9, 95% CI 0.7 to 1.3) but was associated with an increased risk for VaD (1.8 [1.0 to 3.2]). Hypertension was not associated with changes in memory, language, and general cognitive function in normal individuals over time. Compared with individuals with neither hypertension nor heart disease, those with hypertension or heart disease alone had no increase in risk for VaD. However, when both were present, there was a threefold increase in risk for VaD. A sixfold increase in risk was observed when both hypertension and diabetes were present. Conclusions: Hypertension after age 65 years is not associated with AD and does not adversely affect memory, language, or general cognitive function. A history of hypertension may be an antecedent to VaD, particularly in the presence of heart disease or diabetes

Diagnosis of Dementia in a Heterogeneous Population: Development of a Neuropsychological Paradigm-Based Diagnosis of Dementia and Quantified Correction for the Effects of Education

A brief diagnostic battery of neuropsychological tests was developed for a large-scale epidemiological study of dementia. We operationally defined dementia as defective memory and defective performance in at least two other areas, including orientation, abstract reasoning, construction, and language. Criterion scores for defining defective performance on each test were developed. In a pilot study that used 51 different subjects with a working diagnosis based on physicians' assessment (ie, 32 demented and 29 nondemented subjects), the test-based diagnosis agreed with the working diagnosis in all but two cases. The test battery was then applied to 430 healthy elderly subjects. Eighteen percent of those with 8 or less years of education met criteria for dementia compared with 5% of those with more than 8 years of education. We computed educationcorrected scores for each test with the use of residuals from the regression of each test score on education. Based on corrected scores, 12 subjects were reclassified as nondemented and 11 as demented. Subjects who were reclassified as demented were significantly more impaired in activities of daily living than nondemented subjects who were not reclassified. Activities of daily living in subjects who were reclassified as nondemented did not differ from those in demented subjects who were not reclassified. These findings suggest that the neuropsychological battery may have utility in the diagnosis of dementia. However, neuropsychological performance may be influenced by education, and some form of adjustment, such as correction for activities of daily living, may be required in epidemiological studies

Consistency of Clinical Diagnosis in a Community-Based Longitudinal Study of Dementia and Alzheimer's Disease

We evaluated the consistency of the diagnosis of dementia in a multicultural, longitudinal community-based study of cognitive impairment and dementia. We diagnosed dementia using a fixed neuropsychological paradigm; the diagnosis also required historical evidence of functional impairment. In a sample of 656 subjects with at least one annual follow-up examination, dementia was confirmed at 1 year in 89% of the 304 subjects initially demented, and in 90% of the 136 subjects with the initial diagnosis of probable Alzheimer's disease (AD). The 34 initially demented subjects who failed to meet criteria for dementia at follow-up included 13 with an initial diagnosis of probable AD. All 34 still had evidence of cognitive impairment; this group was more likely to have a history of pulmonary disease, multiple medication use, or chronic alcohol use than other demented patients. Consistency of dementia diagnosis did not vary according to educational attainment or ethnic background. The use of a neuropsychological paradigm such as ours in large longitudinal studies of dementia may minimize interobserver diagnostic variability or diagnostic drift over time while contributing the benefits of a comprehensive cognitive evaluation to the diagnostic process

Incidence of AD in African-Americans, Caribbean Hispanics, and Caucasians in Northern Manhattan

Objective: To compare the incidence rates for AD among elderly African-American, Caribbean Hispanic, and white individuals and to determine whether coincident cerebrovascular disease contributes to the inconsistency in reported differences among ethnic groups. Methods: This was a population-based, longitudinal study over a 7-year period in the Washington Heights and Inwood communities of New York City. Annual incidence rates for AD were calculated and compared by ethnic group, and cumulative incidence adjusted for differences in education, diabetes, cardiovascular risk factors, and stroke was calculated. Results: The age-specific incidence rate for probable and possible AD was 1.3% (95% CI, 0.8 to 1.7) per person-year between the ages of 65 and 74 years, 4.0% (95% CI, 3.2 to 4.8) per person-year between ages 75 and 84 years, and 7.9% (95% CI, 5.5 to 10.5) per person-year for ages 85 and older. Compared to white individuals, the cumulative incidence of AD to age 90 years was increased twofold among African-American and Caribbean Hispanic individuals. Adjustment for differences in number of years of education, illiteracy, or a history of stroke, hypertension, heart disease, or diabetes did not change the disproportionate risks among the three ethnic groups. Conclusion: The incidence rate for AD was significantly higher among African-American and Caribbean Hispanic elderly individuals compared white individuals. The presence of clinically apparent cardiovascular or cerebrovascular disease did not contribute to the increased risk of disease. Because the proportion of African-American and Caribbean Hispanic individuals reaching ages 65 and older in the United States is increasing more rapidly than the proportion of white individuals, it is imperative that this disparity in health among the elderly be understood

Further Examination of the Candidate Genes in Chromosome 12p13 Locus for Late-Onset Alzheimer Disease

A broad region on chromosome 12p13 has been intensely investigated for novel genetic variants associated with Alzheimer disease (AD). We examined this region with 23 microsatellite markers using 124 North European (NE) families and 209 Caribbean Hispanic families with late-onset AD (FAD). Significant evidence for linkage was present in a 5-cM interval near 20 cM in both the NE FAD (LOD = 3.5) and the Caribbean Hispanic FAD (LOD = 2.2) datasets. We further investigated these families and an independent NE case-control dataset using 14 single nucleotide polymorphisms (SNPs). The initial screening of the region at approximately 20 cM in the NE case-control dataset revealed significant association between AD and seven SNPs in several genes, with the strongest result for rs2532500 in TAPBPL (p = 0.006). For rs3741916 in GAPDH, the C allele, rather than the G allele as was observed by Li et al. (Proc Natl Acad Sci U S A 101(44):15688-15693, 2004), was the risk allele. When the two family datasets were examined, none of the SNPs were significant in NE families, but two SNPs were associated with AD in Caribbean Hispanics: rs740850 in NCAPD2 (p = 0.0097) and rs1060620 in GAPDH (p = 0.042). In a separate analysis combining the Caribbean Hispanic families and NE cases and controls, rs740850 was significant after correcting for multiple testing (empirical p = 0.0048). Subsequent haplotype analyses revealed that two haplotype sets-haplotype C-A at SNPs 6-7 within NCAPD2 in Caribbean Hispanics, and haplotypes containing C-A-T at SNPs 8-10 within GAPDH in Caribbean Hispanic family and NE case-control datasets-were associated with AD. Taken together, these SNPs may be in linkage disequilibrium with a pathogenic variant(s) on or near NCAPD2 and GAPD

Fine Mapping of 10q and 18q for Familial Alzheimer's Disease in Caribbean Hispanics

Familial Alzheimer's disease (AD [MIM 104300]) has been a focus of intense investigation, primarily in Caucasian families from Europe and North America families. Although the late-onset form of familial AD, beginning after age 65 years, has been linked to regions on chromosomes 10q and 12p, the specific genetic variants have not yet been consistently identified. Using a unique cohort of families of Caribbean Hispanics ancestry, we screened the genome using 340 markers on 490 family members from 96 families with predominantly late-onset AD. We observed the strongest support for linkage on 18q (LOD=3.14). However, 17 additional markers (chromosomes 1-6, 8, 10, 12, and 14) exceeded a two-point LOD score of 1.0 under the affecteds-only autosomal dominant model or affected sibpair model. As we previously reported the fine-mapping effort on 12p showing modest evidence of linkage, we focused our fine-mapping efforts on two other candidate regions in the current report, namely 10q and 18q. We added 31 family members and eight additional Caribbean Hispanic families to fine map 10q and 18q. With additional microsatellite markers, the evidence for linkage for 18q strengthened near 112 cM, where the two-point LOD score for D18S541 was 3.37 and the highest NPL score in that region was 3.65 (P=0.000177). This narrow region contains a small number of genes expressed in the brain. However, at 10q (134-138 cM), the NPL score decreased from 3.15 (P=0.000486) to 2.1 (P=0.0218), but two broad peaks remained overlapping with previously reported peaks. Our results provide modest support for linkage on 10q and 12p in this cohort of Caribbean Hispanic families with familial Alzheimer's disease, and strong evidence for a new locus on 18

Diagnosis of Dementia in a Heterogeneous Population: Development of a Neuropsychological Paradigm-Based Diagnosis of Dementia and Quantified Correction for the Effects of Education

A brief diagnostic battery of neuropsychological tests was developed for a large-scale epidemiological study of dementia. We operationally defined dementia as defective memory and defective performance in at least two other areas, including orientation, abstract reasoning, construction, and language. Criterion scores for defining defective performance on each test were developed. In a pilot study that used 51 different subjects with a working diagnosis based on physicians' assessment (ie, 32 demented and 29 nondemented subjects), the test-based diagnosis agreed with the working diagnosis in all but two cases. The test battery was then applied to 430 healthy elderly subjects. Eighteen percent of those with 8 or less years of education met criteria for dementia compared with 5% of those with more than 8 years of education. We computed educationcorrected scores for each test with the use of residuals from the regression of each test score on education. Based on corrected scores, 12 subjects were reclassified as nondemented and 11 as demented. Subjects who were reclassified as demented were significantly more impaired in activities of daily living than nondemented subjects who were not reclassified. Activities of daily living in subjects who were reclassified as nondemented did not differ from those in demented subjects who were not reclassified. These findings suggest that the neuropsychological battery may have utility in the diagnosis of dementia. However, neuropsychological performance may be influenced by education, and some form of adjustment, such as correction for activities of daily living, may be required in epidemiological studies

Relative Rates of Dementia by Multiple Case Definitions, over Two Prevalence Periods, in Three Cultural Groups

The North Manhattan Aging Project registry, using both Reporting and Survey Components, identifies dementia cases among Latino, African-American, and non-Latino white sociocultural groups (9,349 persons 65 years of age or older) in contiguous census tracts. During a 2-year prevalence period of the reporting component, 1,592 persons were reported to the Registry and screened with five widely used brief cognitive measures; 844 were evaluated in a “clinical core,” and 452 met research criteria for dementia, covering all subtypes, according to DSM-III-R criteria. Thirteen different case definitions for dementia were applied to the sociocultural groups at three levels of educational achievement, examining for associations with rates of dementia cases and controlling for age. The following findings were robust across case definitions: sociocultural membership was not associated, but lower education was associated, with increased rates of recorded dementia; however, the patterns of the association with education varied across sociocultural groups

The Apoe-Epsilon4 Allele and the Risk of Alzheimer Disease among African Americans, Whites, and Hispanics

CONTEXT: Although the association between Alzheimer disease (AD) and the apolipoprotein E epsilon4 (APOE-epsilon4) allele has been confirmed worldwide, it appears to be inconsistent among African Americans, Hispanics, and Nigerians. OBJECTIVE: To investigate the association between the APOE-epsilon4 allele and AD in elderly African Americans, Hispanics, and whites. DESIGN: Prospective, population-based, longitudinal study over a 5-year period (1991-1996). SETTING: The Washington Heights-Inwood community of New York City. PARTICIPANTS: A total of 1079 Medicare recipients without AD or a related disorder at baseline. MAIN OUTCOME MEASURES: Risk of clinically diagnosed AD in the 3 ethnic groups and among individuals with and without an APOE-epsilon4 allele. RESULTS: Compared with individuals with the APOE-epsilon3/epsilon3 genotype, the relative risk (RR) of AD associated with 1 or more copies of the APOE-epsilon4 allele was significantly increased among whites (RR, 2.5; 95% confidence interval [CI], 1.1-6.4), but not among African Americans (RR, 1.0; 95% CI, 0.6-1.6) or Hispanics (RR, 1.1; 95% CI, 0.7-1.6). In the absence of the APOE-epsilon4 allele, the cumulative risks of AD to age 90 years, adjusted for education and sex, were 4 times higher for African Americans (RR, 4.4; 95% CI, 2.3-8.6) and 2 times higher for Hispanics (RR, 2.3; 95% CI, 1.2-4.3) than for whites. In the presence of an APOE-epsilon4 allele, the cumulative risk of AD to age 90 years was similar for individuals in all 3 ethnic groups. CONCLUSION: The presence of an APOE-epsilon4 allele is a determinant of AD risk in whites, but African Americans and Hispanics have an increased frequency of AD regardless of their APOE genotype. These results suggest that other genes or risk factors may contribute to the increased risk of AD in African Americans and Hispanics

The Association Between Genetic Variants in SORL1 and Alzheimer Disease in an Urban, Multiethnic, Community-Based Cohort

Objective: To investigate the association between Alzheimer disease (AD) and variant alleles in SORL1 using a series of single nucleotide polymorphisms (SNPs) in an urban, multiethnic, community-based population. Design: We used a nested case-control analysis in a population-based, prospective study of aging and dementia in Medicare recipients, 65 years and older. Setting: Northern Manhattan, NY. Participants: There were 296 patients with probable AD and 428 healthy, elderly controls. The participants were African American (34%), Caribbean Hispanic (51%), or non-Hispanic white (15%). Main Outcome Measures: We genotyped all 29 SNPs in SORL1 that were examined in the earlier report. We assessed allelic association with AD using standard case-control methods, which included apolipoprotein E genotype as a covariate. Results: Several individual SNPs and SNP haplotypes were significantly associated with AD in this prospectively collected community-based cohort, confirming the previously reported positive association of SORL1 with AD. Single nucleotide polymorphism 12, near the 5′ region, was associated with AD in African American and Hispanic individuals. Two SNPs in the 3′ region were also associated with AD in African American (SNP 26) and non-Hispanic white (SNP 20) individuals. A single haplotype in the 3′ region was associated with AD in Hispanic individuals. However, several different haplotypes were associated with AD in African American and white individuals, including the TTC haplotypes at SNPs 23 through 25 (P = .035), which was significantly associated with AD in the North European white individuals in our previous report. Conclusions: This study confirms the association between genetic variants in SORL1 and AD. While the associations observed in these data sets overlap with those previously reported, the finding of novel SNP and haplotype associations suggests that there may be extensive allelic heterogeneity in SORL1. Broad regions of the SORL1 gene will therefore need to be scrutinized for functional pathogenic variants