Cognitive decline after hospitalization in a community population of older persons.

OBJECTIVE: To test the hypothesis that hospitalization in old age is associated with subsequent cognitive decline. METHODS: As part of a longitudinal population-based cohort study, 1,870 older residents of an urban community were interviewed at 3-year intervals for up to 12 years. The interview included a set of brief cognitive tests from which measures of global cognition, episodic memory, and executive function were derived. Information about hospitalization during the observation period was obtained from Medicare records. RESULTS: During a mean of 9.3 years, 1,335 of 1,870 persons (71.4%) were hospitalized at least once. In a mixed-effects model adjusted for age, sex, race, and education, the global cognitive score declined a mean of 0.031 unit per year before the first hospitalization compared with 0.075 unit per year thereafter, a more than 2.4-fold increase. The posthospital acceleration in cognitive decline was also evident on measures of episodic memory (3.3-fold increase) and executive function (1.7-fold increase). The rate of cognitive decline after hospitalization was not related to the level of cognitive function at study entry (r = 0.01, p = 0.88) but was moderately correlated with rate of cognitive decline before hospitalization (r = 0.55, p = 0.021). More severe illness, longer hospital stay, and older age were each associated with faster cognitive decline after hospitalization but did not eliminate the effect of hospitalization. CONCLUSION: In old age, cognitive functioning tends to decline substantially after hospitalization even after controlling for illness severity and prehospital cognitive decline.

Change in risk of Alzheimer disease over time.

OBJECTIVE: To assess whether the risk of incidence of Alzheimer disease (AD) varies over time. The increase in numbers of people at the oldest ages in the population will bring an increase in the number of people with AD. Projections of the size of the increase assume the risk of AD is constant. METHODS: All persons age 65 or older in a biracial, geographically defined area were invited to participate in a home interview every 3 years. From the approximately 10,000 participants, stratified random samples were selected for detailed clinical evaluation. At each cycle, individuals determined free of AD in a previous cycle, either by examination or by high score on cognitive function tests, were sampled in the subsequent cycle for evaluation for incident AD. The evaluations for disease were structured and uniform across time. These analyses include 1,695 subjects evaluated for incident disease from 1997 through 2008. RESULTS: AD developed in 360 participants. Change over time in risk of incident disease was assessed in logistic regression analyses including evaluation date and controlling for age, gender, education, race, interval from disease-free designation to evaluation for incident disease, and sample design. The time variable (in years) was not significant (odds ratio = 0.970, 95% confidence interval = 0.902 to 1.044). CONCLUSIONS: The null relation of evaluation date to disease incidence suggests no recent change in risk of AD over time, and supports this assumption for projections of AD.

Cognitive activity and the cognitive morbidity of Alzheimer disease.

OBJECTIVE: To test the hypothesis that frequent cognitive activity predicts slower cognitive decline before dementia onset in Alzheimer disease (AD) and faster decline thereafter. METHODS: As part of a longitudinal cohort study, older residents of a geographically defined population were assessed at 3-year intervals with brief cognitive performance tests from which a composite measure of global cognition was derived. After each wave of testing, a subset was sampled for clinical evaluation. The present analyses are based on 1,157 participants. They were free of dementia at study enrollment at which time they rated frequency of participation in common cognitively stimulating activities from which a previously validated summary measure was derived. They were sampled for clinical evaluation a mean of 5.6 years after enrollment and subsequently followed a mean of 5.7 years with brief cognitive performance testing at 3-year intervals. RESULTS: On clinical evaluation, 614 people had no cognitive impairment, 395 had mild cognitive impairment, and 148 had AD. During follow-up, the annual rate of global cognitive decline in persons without cognitive impairment was reduced by 52% (estimate = 0.029, SE = 0.010, p = 0.003) for each additional point on the cognitive activity scale. In the mild cognitive impairment group, cognitive decline rate was unrelated to cognitive activity (estimate = -0.019, SE = 0.018, p = 0.300). In AD, the mean rate of decline per year increased by 42% (estimate = 0.075, SE = 0.021, p < 0.001) for each point on the cognitive activity scale. CONCLUSION: Mentally stimulating activity in old age appears to compress the cognitive morbidity associated with AD by slowing cognitive decline before dementia onset and hastening it thereafter.

Cognitive decline in incident Alzheimer disease in a community population.

OBJECTIVE: To measure the cognitive consequences of incident Alzheimer disease (AD) in older African American and white subjects. METHODS: Data are from the Chicago Health and Aging Project, a longitudinal cohort study of older white and black persons residing in a geographically defined community. At 3-year intervals, the entire study population completed 4 brief cognitive tests, from which a previously established composite measure of global cognition was derived, and a subset underwent detailed clinical evaluation that supported clinical classification of mild cognitive impairment, dementia, and AD. We used mixed-effects models to examine change in cognitive function following the diagnostic evaluation. RESULTS: On clinical evaluation, 614 persons were found to have no cognitive impairment, 395 had mild cognitive impairment, and 149 had AD (88.5% mild); 10 persons with other dementias were excluded from analyses. During up to 11 years of observation following the clinical evaluation (mean = 5.5, SD = 2.5), the composite measure of global cognition declined a mean of 0.042 unit per year (SE = 0.008, p < 0.001) in those with no cognitive impairment. In comparison to the no cognitive impairment group, the annual rate of decline was increased more than twofold in mild cognitive impairment (estimate = 0.086, SE = 0.011, p < 0.001) and more than fourfold in AD (estimate = 0.173, SE = 0.020, p < 0.001). Results did not reliably vary by race, sex, or age. CONCLUSIONS: Alzheimer disease has a devastating impact on cognition, even in its prodromal stages, with comparable effects in African American and white persons.

Educational attainment and cognitive decline in old age.

BACKGROUND: Level of education is a well-established risk factor for Alzheimer disease but its relation to cognitive decline, the principal clinical manifestation of the disease, is uncertain. METHODS: More than 6,000 older residents of a community on the south side of Chicago were interviewed at approximately 3-year intervals for up to 14 years. The interview included administration of four brief tests of cognitive function from which a previously established composite measure of global cognition was derived. We estimated the associations of education with baseline level of cognition and rate of cognitive change in a series of mixed-effects models. RESULTS: In an initial analysis, higher level of education was related to higher level of cognition at baseline, but there was no linear association between education and rate of change in cognitive function. In a subsequent analysis with terms to allow for nonlinearity in education and its relation to cognitive decline, rate of cognitive decline at average or high levels of education was slightly increased during earlier years of follow-up but slightly decreased in later years in comparison to low levels of education. Findings were similar among black and white participants. Cognitive performance improved with repeated test administration, but there was no evidence that retest effects were related to education or attenuated education's association with cognitive change. CONCLUSIONS: The results suggest that education is robustly associated with level of cognitive function but not with rate of cognitive decline and that the former association primarily accounts for education's correlation with risk of dementia in old age.

Dietary niacin and the risk of incident Alzheimer's disease and of cognitive decline.

BACKGROUND: Dementia can be caused by severe niacin insufficiency, but it is unknown whether variation in intake of niacin in the usual diet is linked to neurodegenerative decline. We examined whether dietary intake of niacin was associated with incident Alzheimer's disease (AD) and cognitive decline in a large, prospective study. METHODS: This study was conducted in 1993-2002 in a geographically defined Chicago community of 6158 residents aged 65 years and older. Nutrient intake was determined by food frequency questionnaire. Four cognitive tests were administered to all study participants at 3 year intervals in a 6 year follow up. A total of 3718 participants had dietary data and at least two cognitive assessments for analyses of cognitive change over a median 5.5 years. Clinical evaluations were performed on a stratified random sample of 815 participants initially unaffected by AD, and 131 participants were diagnosed with 4 year incident AD by standardised criteria. RESULTS: Energy adjusted niacin intake had a protective effect on development of AD and cognitive decline. In a logistic regression model, relative risks (95% confidence intervals) for incident AD from lowest to highest quintiles of total niacin intake were: 1.0 (referent) 0.3 (0.1 to 0.6), 0.3 (0.1 to 0.7), 0.6 (0.3 to 1.3), and 0.3 (0.1 to 0.7) adjusted for age, sex, race, education, and ApoE e4 status. Niacin intake from foods was also inversely associated with AD (p for linear trend = 0.002 in the adjusted model). In an adjusted random effects model, higher food intake of niacin was associated with a slower annual rate of cognitive decline, by 0.019 standardised units (SU) per natural log increase in intake (mg) (p = 0.05). Stronger associations were observed in analyses that excluded participants with a history of cardiovascular disease (beta = 0.028 SU/year; p = 0.008), those with low baseline cognitive scores (beta = 0.023 SU/year; p = 0.02), or those with fewer than 12 years' education (beta = 0.035 SU/year; p = 0.002) CONCLUSION: Dietary niacin may protect against AD and age related cognitive decline.

Blood pressure and late-life cognitive function change: a biracial longitudinal population study.

OBJECTIVE: To examine the relation of blood pressure (BP) to subsequent decline in cognitive function among persons age 65 or over. METHODS: All persons age 65 or over in a geographically defined community were invited to participate in a longitudinal study of problems of the elderly. Interviews were conducted in the participants' homes and included two BP measures and four tests of cognitive function. Follow-up interviews 3 and 6 years after baseline repeated the cognitive function tests. These analyses included 4,284 individuals who had baseline and at least one follow-up measure of cognitive function. The average of z scores of the individual cognitive function tests was used as a global measure of cognitive function. RESULTS: In random effects analyses controlling for age, sex, education, and race, there was no significant linear association of either systolic or diastolic BP with 6-year change in global cognitive function score. There was no significant curvilinear association with systolic BP. In tests for a curvilinear association with diastolic BP, there was a suggestion of increased decline among those with low or high diastolic BP (p = 0.03 for the quadratic diastolic term). At baseline, 50% of participants took some type of medication affecting BP. CONCLUSION: In this community population where BP treatment was common, there was no association of either high systolic or high diastolic BP at the beginning of the observation interval with 6-year cognitive decline.

Annual incidence of Alzheimer disease in the United States projected to the years 2000 through 2050.

Alzheimer disease will affect increasing numbers of people as baby boomers (persons born between 1946 and 1964) age. This work reports projections of the incidence of Alzheimer disease(AD) that will occur among older Americans in the future. Education adjusted age-specific incidence rates of clinically diagnosed probable AD were obtained from stratified random samples of residents 65 years of age and older in a geographically defined community. These rates were applied to U.S. Census Bureau projections of the total U.S. population by age and sex to estimate the number of people newly affected each year. The annual number of incident cases is expected to more than double by the midpoint of the twenty-first century: from 377,000 (95% confidence interval = 159,000-595,000) in 1995 to 959,000 (95% confidence interval = 140,000-1,778,000) in 2050. The proportion of new onset cases who are age 85 or older will increase from 40% in 1995 to 62% in 2050 when the youngest of the baby boomers will attain that age. Without progress in preventing or delaying onset of Alzheimer disease, both the number of people with Alzheimer disease and the proportion of the total population affected will increase substantially.

Association of incident Alzheimer disease and blood pressure measured from 13 years before to 2 years after diagnosis in a large community study.

BACKGROUND: It is uncertain whether high blood pressure increases the risk of developing Alzheimer disease (AD). OBJECTIVE: To examine the association between incident AD and blood pressure measured up to 13 years before diagnosis. DESIGN: Longitudinal cohort study conducted from 1982 to 1988, with blood pressure measured every 3 years in home interviews, and in 1973 for a portion (60%) of the sample. SETTING: Community of East Boston, Mass. PARTICIPANTS: Six hundred thirty-four subjects 65 years or older and without AD were selected as a stratified random sample of participants of the East Boston Established Populations for Epidemiologic Studies of the Elderly. MAIN OUTCOME MEASURE: Alzheimer disease was diagnosed by a neurologist using a structured clinical evaluation. RESULTS: High blood pressure was not associated with an increased risk of AD in logistic regression models adjusted for age, sex, and level of education. There was no association with systolic pressure measured 13 years before diagnosis (odds ratio = 1.03/10 mm Hg; 95% confidence interval, 0.80-1.32) and an inverse association with systolic pressure measured 4 years before diagnosis (odds ratio = 0.82/10 mm Hg; 95% confidence interval, 0.72-0.95). Associations for diastolic pressure were in the same direction as those for systolic pressure except with wider confidence intervals. The odds ratios were not materially different with further adjustment for cardiovascular risk factors and diseases. CONCLUSION: In this large community study, high blood pressure was not associated with an increased risk of AD.

Is the risk of developing Alzheimer's disease greater for women than for men?

A large proportion of people with Alzheimer's disease (AD) are women; however, it is not clear whether this is due to higher risk of disease or solely to the larger number of women alive at ages when AD is common. Beginning in 1982, two stratified random samples of people aged > or =65 years in East Boston, Massachusetts underwent detailed, structured clinical evaluation for prevalent (467 people) and incident (642 people from a cohort previously ascertained to be disease-free) probable AD. The prevalence sample was followed for mortality for up to 11 years (through December 1992). The age-specific incidence of AD did not differ significantly by sex (for men vs. women, odds ratio = 0.92; 95% confidence interval (CI): 0.51, 1.67). Controlled for age, prevalence also did not differ significantly by sex (for men vs. women, odds ratio = 1.29; 95% CI: 0.67, 2.48). The increase in risk of mortality due to AD did not vary by sex. The odds ratio for women with AD compared with women without AD was 2.07 (95% CI: 1.21, 3.56). For men, the odds ratio was 2.22 (95% CI: 1.02, 4.81). These findings suggest that the excess number of women with AD is due to the longer life expectancy of women rather than sex-specific risk factors for the disease.

Comparison of informal caregiving by black and white older adults in a community population.

OBJECTIVES: To examine the prevalence of informal caregiving and demographic factors associated with caregiving time in older community residents and compare caregiving prevalence and time spent providing care by black and white residents. DESIGN: A cross-sectional, population-based study. SETTING: The study was conducted as part of the Chicago Health and Aging Project (CHAP) in a geographically defined community of black and white residents aged 65 and older. PARTICIPANTS: Participants were 5,924 community residents (61.4% black; 38.6% white) who answered questions about informal caregiving responsibilities during a structured interview about a broad range of health and social factors. METHODS: Data were collected during an in-home interview. Multiple logistic and linear regression models were used to examine the association between caregiving and race, gender, age, marital status, and education. RESULTS: More than 16% of residents had provided care to others during the previous 12 months, and 10.3% were currently providing care. Compared with whites, blacks were 30% more likely to be caregivers, spent almost 13 more hours each week in caregiving activities, and were more likely to assist friends. The probability of caregiving increased significantly with age for married persons, decreased with age for unmarried persons, and was lower for men compared with women. The time spent providing care each week increased significantly with age for married persons and did not differ between men and women. CONCLUSIONS: Although physicians and other healthcare providers typically view older people as the recipients of informal care, individuals older than age 65 provide a substantial amount of care to others with health problems and disability. Most research has focused on the needs of young and middle-aged caregivers, and little is known about the needs of these older caregivers. Future research should use sampling strategies that provide adequate numbers of white and non-white participants for meaningful comparisons. This will permit identification of racial and cultural differences in caregiving so that interventions can be tailored to specific groups.

Decline of language among women and men with Alzheimer's disease.

Previous research raises the possibility that gender differences occur in language function in Alzheimer's disease, but this hypothesis has not been evaluated systematically in longitudinal studies. The authors examined the association of gender with rate of decline in language and other cognitive functions among 410 persons with Alzheimer's disease. Participants were recruited from a dementia clinic and followed for up to 5 annual evaluations. Follow-up participation among survivors exceeded 90%. Decline in a composite score based on 8 language tests was evaluated in random effects models with age, education, and race controlled. Annual decline was 0.71 standard units (95% confidence interval [CI] = 0.62-0.79) for women and 0.74 units (95% CI = 0.61-0.86) for men, not a significant difference. Decline on the individual language tests and on composite measures of memory, perception, and global cognition also indicated no significant association with gender. These results suggest that Alzheimer's disease affects language and other cognitive functions similarly in women and men.

The cross-sectional association between blood pressure and Alzheimer's disease in a biracial community population of older persons.

BACKGROUND: The relation of blood pressure to Alzheimer's disease (AD) is complex because both an association of high blood pressure with increased risk of the disease and lower blood pressure as a consequence of the disease are possible. METHODS: We examined the cross-sectional association of blood pressure and AD in the Chicago Health and Aging Project (CHAP), a study of a geographically defined, biracial community. After in-home interviews with 6.162 residents > or =65 years, a stratified random sample of 729 participants was clinically evaluated; 709 had blood pressures measured, and 243 were diagnosed with AD. RESULTS: In logistic regression models adjusted for age, sex, education, and race there was no association between blood pressure measured as a continuous variable and Alzheimer's disease. In categorical analyses, however, prevalence of Alzheimer's disease was significantly higher among persons with low systolic pressure (<130 mmHg) compared with the referent group of 130-139 mmHg (odds ratio [OR] = 2.2, 95% confidence interval [CI]: 1.2,4.1), and with low diastolic pressure (<70 mmHg) compared to the referent of 70-79 mmHg (OR = 1.8, 95% CI: I. 1,3.1). High systolic and diastolic categories were not statistically different from the referent group, although there was some evidence that the associations differed by race. The odds ratios changed little with further adjustment for apolipoprotein E genotype, antihypertensive medications, body mass, stroke, diabetes, and heart disease. CONCLUSION: These findings are consistent with previous studies showing associations between low blood pressure and AD, but longitudinal studies are needed to characterize cause-and-effect associations.

Methodological issues in the study of cognitive decline.

In recent years, epidemiologists have given increased attention to cognition, especially to the dementing illnesses that occur in old age. Central to this study is the measurement of change in cognition as opposed to cognition measured at a single point in time. This article addresses conceptual and methodological issues in the study of changes in cognitive function, including: 1) difficulties encountered with the use of single measurements of cognition and the importance of measuring changes in cognition; 2) sources of measurement variation and its potential effects; 3) the importance of careful modeling of age and education; 4) considerations in categorizing outcomes or combining the results of cognitive tests; and 5) the benefits of using multiple-outcome statistical models.

Current and remote blood pressure and cognitive decline.

CONTEXT: Previous studies raise the possibility that blood pressure (BP) in middle age predicts later cognitive decline. OBJECTIVE: To examine prospectively the relationship of BP with level of and change in cognitive function in the elderly. DESIGN: Longitudinal, population-based study comprising subjects enrolled in the East Boston component of the Established Populations for the Epidemiologic Study of the Elderly (EPESE) (1982-1983) and the Hypertension Detection and Follow-Up Program (HDFP) (1973-1974). SETTING: East Boston, Mass. PARTICIPANTS: Of the 3657 participants in the EPESE with baseline BP measurements, 2068 also participated in the HDFP. Subjects were aged 65 to 102 years at baseline in the EPESE and had mental status and memory assessed at baseline and 3 and 6 years. MAIN OUTCOME MEASURES: Numbers of errors on the Short Portable Mental Status Questionnaire and the East Boston Memory Test and rates of change in these numbers of errors. Subjects had BP measured both at baseline in the EPESE and 9 years before, as part of the HDFP. RESULTS: In analyses adjusted for age, sex, and education, there was no strong linear association between BP and cognition. The associations found were fairly small in magnitude, and varied according to which test was used to measure cognition. There was little evidence for an effect of BP on change in cognitive function with either test, or for an effect on level of function on the memory test. In analyses of level of mental status questionnaire performance, however, elevated systolic BP (> or =160 mm Hg) 9 years before baseline was associated with a 14% (95% confidence interval [CI], 4%-25%) increase in error rate, relative to the referent (130-139 mm Hg). Baseline systolic BP had a U-shaped association with the number of errors; error rates were 9% higher compared with the referent group among those with systolic BP lower than 130 mm Hg (95% CI, 1%-17%) and 7% greater (95% CI, 0%-15%) among those with elevated systolic BP. Diastolic BP 9 years before baseline also had a U-shaped association with errors on the mental status questionnaire. CONCLUSION: The findings do not suggest a linear association of BP with cognitive decline, but they are consistent with a more complex relationship between BP and cognition than previously appreciated.

Vitamin E and vitamin C supplement use and risk of incident Alzheimer disease.

Oxidative stress may play a role in neurologic disease. The present study examined the relation between use of vitamin E and vitamin C and incident Alzheimer disease in a prospective study of 633 persons 65 years and older. A stratified random sample was selected from a disease-free population. At baseline, all vitamin supplements taken in the previous 2 weeks were identified by direct inspection. After an average follow-up period of 4.3 years, 91 of the sample participants with vitamin information met accepted criteria for the clinical diagnosis of Alzheimer disease. None of the 27 vitamin E supplement users had Alzheimer disease compared with 3.9 predicted based on the crude observed incidence among nonusers (p = 0.04) and 2.5 predicted based on age, sex, years of education, and length of follow-up interval (p = 0.23). None of the 23 vitamin C supplement users had Alzheimer disease compared with 3.3 predicted based on the crude observed incidence among nonusers (p = 0.10) and 3.2 predicted adjusted for age, sex, education, and follow-up interval (p = 0.04). There was no relation between Alzheimer disease and use of multivitamins. These data suggest that use of the higher-dose vitamin E and vitamin C supplements may lower the risk of Alzheimer disease.

Education and other measures of socioeconomic status and risk of incident Alzheimer disease in a defined population of older persons.

OBJECTIVE: To assess the relations of 3 measures of socioeconomic status (education, occupational prestige, and income) to risk of incident clinically diagnosed Alzheimer disease (AD). DESIGN: Cohort study with an average observation of 4.3 years. SETTING: East Boston, Mass. a geographically defined community. PARTICIPANTS: A stratified random sample of 642 community residents 65 years of age and older who were free of AD at baseline. MAIN OUTCOME MEASURE: Clinical diagnosis of probable AD according to standard criteria, using structured uniform evaluation. RESULTS: The relations of the 3 measures of socioeconomic status to risk of disease were assessed using logistic regression analyses. In individual analyses, fewer years of formal schooling, lower income, and lower occupational status each predicted risk of incident AD; risk of disease decreased by approximately 17% for each year of education. In an analysis including all 3 measures, the effect of education on risk for disease remained approximately the same, but the effects of the other 2 measures were somewhat less and did not attain formal statistical significance, compared with separate analysis of each measure. CONCLUSIONS: Markers of lower socioeconomic status predict risk of developing incident AD. The mechanism of this relation is uncertain, but the possibility that it reflects unidentified and potentially reversible risk factors for the disease deserves careful investigation.

Why Alzheimer's disease is a women's health issue.

Alzheimer's disease is not typically included on the list of important women's health issues. Yet Alzheimer's disease is indeed a women's disease. Not only do more women than men have Alzheimer's disease, but women also provide a disproportionate amount of the informal community care for people with the disease. The prevalence of Alzheimer's disease increases dramatically with age and is highest among those 85 years of age and older. Women make up 72% of the US population over age 85 and, therefore, are the group most affected by the disease. By the year 2050, the number of people with Alzheimer's disease will more than double from approximately 4 million to 10 million, and 70% of these people will be age 85 or older. Although the symptoms and course of Alzheimer's disease may be similar in women and men, social and economic factors may produce a greater burden of disease among women, particularly with respect to the types and quality of health care services they receive, because women generally have the most limited social and financial resources. As the population ages, typical patients with Alzheimer's disease will be much older, frailer, and will have more functional impairments and chronic diseases than the patients most physicians see today. Future research needs to focus on identifying modifiable risk factors and effective treatments for Alzheimer's disease, and on determining the appropriate types of community-based and institutional services required to care for those with the illness as well as their families.

Concordance between direct observation and staff rating of behavior in nursing home residents with Alzheimer's disease.

This study examined concordance between staff ratings and direct observations of behavior in 177 nursing home residents with Alzheimer's disease. During a structured interview, the staff member who had the most frequent contact with each resident completed three standardized behavioral rating scales. Direct observation of behavior (60 observations per resident) was conducted concurrently by trained nonparticipant observers using a structured time-sampling technique. We found moderate agreement between the two sources for the occurrence of 12 target behaviors during the monitoring period, but generally low agreement regarding the frequency of these behaviors. Discrepancies regarding occurrence of behavior were non-random with a higher rate of detection by direct observation. Thus, the practical advantages of staff ratings of behavior in institutional settings may be partly offset by some reduction in the accuracy of enumeration.