Research

Pilot Projects

Title: Environmental Contributions to Accelerated Physiologic Aging
Investigators: Frank Gilliland
Project Description:  The aim of this project is to develop preliminary data to study the contribution of ambient particulate matter to inflammatory responses in young adults.  Based on a growing body of evidence that supports the hypothesis that chronic inflammatory processes are related to accelerated aging as well as to diseases that are important contributors to mortality rates, the objectives of this research on the environmental contribution to aging are: 1) to identify environmental contributors to inflammatory processes involved in aging as measured by age related phenotypes; 2) to assess susceptibility factors for the effects of environmental exposures on chronic inflammation; and 3) to identify groups if young adults who are at the highest risk for accelerated physiologic aging based on patterns of exposure and systemic inflammation.  This project builds on the resources of the TROY study, a study of air pollution, respiratory health and atherosclerosis, which will assess 800 USC freshmen recruited for the study. Health and sociodemographic data will be collected, along with biological markers for analyses. The objective of this project is to develop preliminary data to support an R01 grant application to investigate the contribution of ambient air pollution to accelerated physiologic aging mediated by inflammatory responses in young adults. This study is related to other Center work focused on the lifetime effects of inflammation and is using a portable sonogram to assess intima-media thickness of the carotid artery in the field.

Title: Inflammation, Hemostasis and Acculturation in the Multiethnic Study of Atherosclerosis (MESA)
Investigators: Leo Morales
Project Description: What effects acculturation processes have on cardiovascular risk factors in the foreign-born over time spent living in the United States and over generations is unclear and an area of ongoing research. This study investigates the relationship of acculturation to two novel cardiovascular disease risk factors  inflammation and hemostasis  among Latino and Asian immigrants. Baseline data from the Multiethnic Study of Atherosclerosis (MESA), a rich new data source on older Latinos and Asians, will be analyzed using multivariate methods. MESA is unique in having detailed biometric, social and behavioral data on a large number of older Latino and Asian immigrants making this research possible. The findings will serve as the basis for a larger research proposal to NIA.

Title: Migrant-Nonmigrant Differentials in Cardiovascular Risk Factors in China
Investigators: Peifeng Hu and William M. Mason (with Thom McDade)
Project Description:  The primary aims of this project are to examine migrant-nonmigrant differentials in cardiovascular risk factors and explore the extent to which these differentials might be associated with differences in psychosocial stress, health behaviors, and access to health care.  In this study, data from a 2007 national probability sample of migrants and nonmigrants in China will be analyzed.  This project will be the first study to integrate psychosocial and biological information in the explorations of potential differentials in cardiovascular risk factors across migrant and non-migrant populations in China.  Findings from the study will lead to new RO1 funding to measure biomarkers on stored specimens and to further examine longitudinal relations between migration and health in China.   This project is developing capability of assaying dried blood spots in a lab in Beijing China.  We are hoping to provide this capability for the China HRS blood spots.
Publications: The pre-test data from 197 participants in 10 different townships throughout China have been used to compare migrants to permanent urban residents.  Both rural-to-urban migrants and rural non-migrants in China have higher risk of recent respiratory infections, after adjustment for age, sex, education, smoking, health insurance, number of chronic medical conditions, hazardous working environment, and housing characteristics.  The manuscript describing these findings has just been submitted to the Journal of Epidemiology and Community Health.  Hu also found an association between migration status and self-rated health.  Using permanent urban residents as the reference group, the multiply-adjusted odd ratios of having fair or poor self-rated health were 3.18 (95% CI: 1.17  8.70) for rural non-migrants and 2.21 (95% CI: 0.81  6.25) for rural-to-urban migrants.  The manuscript summarizing these results is currently in preparation.
Related Grants: Dr. Hu is planning to submit a R21 application in June of 2008 to further expand the assay capability at the Capital Medical University and conduct multiple bioassays (including C-reactive protein, total and HDL cholesterols, and hemoglobin) on approximately 3,000 dried blood spot specimens from the “Internal Migration and Health in China” project.
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Title: The effect of childhood experience on adult height differences in identical twins: implications for aging
Investigators: Wendy Cozen, Thomas M. Mack
Project Description: This study investigates the relationship between adult height and health using data from twins in order to control for genetic and nutritional factors.  In this pilot study questions on early childhood exposure to infections are linked to adult height. Further it tests the hypothesis that height is related to childhood experience, in a case-control study of healthy identical twins discordant for height by at least 1 inch. The data are based on both members of 213 healthy identical twin pairs born from 1968 to 1982 from the population-based California Twin Program (CTS) who reported a difference of at least 1 inch in height. The answers are validated by interviewing their mother, asking similar questions about their early experience. Questions include information on childhood infections, contact with pets, fecal-oral exposures, day care and school attendance, growth, diet, exercise, and onset of puberty.  This project provides another approach to the issue of the effect of inflammation on lifetime health.

Title:  Antioxidant and Inflammatory Mechanisms Affecting Cognitive and Physical Functioning
Investigator:  Peifeng Hu
Project Description: This pilot examined simultaneously the effects of serum beta-carotene level and inflammation burden on subsequent mortality. It also examined the role of beta-carotene and APOE in affecting cognitive functioning .  The hypothesis was that there would be a link between adverse levels of serum beta-carotene level and inflammation factors and deterioration in physical and cognitive functioning among older persons.  We also hypothesized that low beta-carotene level and high inflammation burden wouldl independently predict functioning change and there will be a synergistic effect between the two in their association with higher subsequent overall mortality.  An additional hypothesis is that the presence of APOE4 alleles would interact with the level of antioxidant status to affect cognitive functioning. The primary finding was that among high functioning older persons, the effect of low serum beta-carotene level on cognitive decline is confined to those who have APOE 4 alleles, suggesting a genetic influence on the effect of low antioxidant status.
Publications:  Two publications have come out of this work:
Hu P, Bretsky P, Crimmins EM, Guralnik JM, Reuben DB, Seeman TE. The effects of serum beta-carotene levels on decline of cognitive function in high-functioning older persons with or without apolipoprotein E 4 alleles. MacArthur Studies of Successful Aging: Journal of Gerontol: Mel Sci. 200661, 616-620.
Hu P, Reuben DB, Crimmins EM, Harris TB, Huang MH, Seeman TE. The effects of serum beta-carotene concentration and burden of inflammation on all-cause mortality risk in high-functioning older persons: MacArthur studies of successful aging. J Gerontol:Med Sci. 2004;59:849-54.
Related Grants: Based on the results of the pilot project Hu has received grant K32 AG021029.

Title: Education as a Modifier of Rate of Change among Those with Memory Complaints and Mild Cognitive Dysfunction
Investigator:  Wendy Mack    
Project Description: The long run purpose of this study is to evaluate the protective effect of education and other indicators of mental ability or "mental exercise" against cognitive decline. The pilot research examined whether education relates to the timing of shifts from nondemented to mild cognitive impairment and from mild cognitive impairment to dementia, and from diagnosed dementia to death. The hypothesis is that people with higher education will drop faster once they start to decline, because their education protected them from crossing a diagnostic threshold for longer than would be the case for someone less endowed. Thus we would expect that having greater cognitive reserve will protect against onset of clinically diagnosed dementia, while decline after diagnosis will be more abrupt. The work of the pilot project is to develop the data from the ADRC files for such examination and test our ability to use the latent growth curve method with these data. This project will help us evaluate the role of changing educational levels in producing trends in population cognitive ability. This project was the basis of a section of a P01 project.
Publications: The following paper was published. 
Andel R, Vigen C, Mack WJ, Clark LJ, Gatz M. The effect of education and occupational complexity on rate of cognitive decline in Alzheimer's patients. J Int Neuropsychol Soc. 2006;12(1):147-52.
Related Grants:  A major sub-project of the new ADRC grant came out of this pilot work - P50 AG 05142.

Title: Cardiovascular Risk Assessment using Multiple Risk Factors in Older Adults Investigator: Arun Karlamangla
Project Description: Data from the MacArthur Study of Succesful Aging, a longitudinal cohort of relatively high-functioning women and men aged 70-79 years at baseline in 1988, was used for this project. All standard cardiovascular risk factors including CRP were measured at baseline.  Repeat measurements were obtained on all risk factors except for HDL cholesterol and CRP in 1991.  Cardiovascular events and cardiovascular mortality information till 1998 has been collected. The baseline measurements of risk factors among the participants without history of previous diabetes, stroke, or heart attacks, were used to construct a composite risk score.  This score was internally validated using bootstrapping to compare its risk discrimination ability with the Framingham score. The pilot project used stored plasma samples from the 1991 blood draw to measure 1991 values of CRP and HDL cholesterol.  These were used to create change scores reflecting change in the new risk scores between 1988 and 1991, and study the association of these change scores with risk of cardiovascular events and/or cardiovascular mortality between 1991 and 1998.
Publications: The following article resulted from the pilot work.
Karlamangla A, Singer BS, Reuben D, Seeman TE.  Increase in serum non-High-Density Lipoprotein Cholesterol may be beneficial in some high-functioning older adults: MacArthur Studies of Successful Aging. J Am Geriatr Soc. 2004; 52:487-494.
Related Grants: Building on his pilot work, Karlamangla has received R01 AG026108 to create cardiovascular risk scores from multiple risk factors tailored to older adults.  Risk scores have been constructed and are in the process of being validated. 

Title:Predicting Dementia Risk in Elderly Twins from Indicators of Early Life Infection
Investigators: Margaret Gatz
Project Description: This project explores the role of early life conditions in increasing risk of dementia and Alzheimer’s disease (AD). Building on a study showing that tooth loss before age 35 was a significant risk factor for AD, even controlling for socioeconomic status of the rearing household, we use a different data set, the National Academy of Sciences-National Research Council (NAS-NRC) Twin Registry of World War II veterans/Duke Twins Study database, to further test the hypothesis.
We propose to augment the Duke Twins Study database with medical information from 1940s military records, including dental records. That information is archived on microfiche film. The pilot project allows us to contract with the Institute of Medicine (IOM) to extract a portion of these data and transfer them to a usable format that permits merging with the Duke Twins database. The first specific aim is to determine whether tooth loss, as a marker of early life infection, is associated with risk of cognitive decline and dementia. The second specific aim is to determine whether the association between tooth loss, cognitive decline and dementia is primarily due to its role as an indicator of low socioeconomic status.

Title: Examination of the relationship between allostatic load and geriatric frailty across demographic subgroups of the older adult population: The MacArthur Study of Successful Aging
Investigators: Catherine A. Sarkisian and Tara Gruenewald
Project Description: A greater proportion of adults reach old age without disability than ever before, yet clinicians continue to struggle with how to approach the substantial proportion (over 10%) of the older population who develop what is increasingly referred to as the geriatric syndrome of “frailty”: a constellation of problems such as weight loss, muscle wasting, and cessation of physical activity, that cannot be explained by identifiable medical or psychiatric diseases. This investigative team proposes to use data from the MacArthur Study of Successful Aging (MSSA), a longitudinal cohort of 1189 high-functioning Americans, to examine whether and to what extent “allostatic load” predicts geriatric frailty across demographic subgroups. Allostatic load explicitly considers the simultaneous and potentially cumulative impacts of physiological effects from multiple regulatory systems before they become clinically manifest as frailty, fitting very well with the theoretical framework of frailty as a cycle of declining reserves across physiologic systems. Proposed analyses offer the potential to identify dysregulatory pathways across one or multiple physiological systems preceding onset of geriatric frailty, thus suggesting possible opportunities to intervene to prevent frailty across the population. This exploratory investigation would provide preliminary data laying the groundwork for an RO1 application to NIA to extend these findings in larger more diverse samples of older adults including the Health ABC study and Hispanic EPESE.

Title: Comparison of different methods for measuring HbA1c in epidemiologic studies
Investigators: Orpheu Buxton
Project Description: This project combines the assessment of three methods for determining HbA1c levels as used in clinical trials currently conducted by the PI of this proposal, ongoing epidemiologic studies using a portable device that gives rapid feedback, and dried blood spots appropriate for large-scale studies. The results are expected to provide a ‘Rosetta Stone’ for comparing the three methods and for interpretation of results across different studies. Finally, the proposed pilot will provide additional pilot data for the PI to submit a K award to the NIA and other federal and foundation grants that should facilitate the entry of the PI to the field of Aging research and the study of the social determinants of health.

Title: Neighborhood Context and Mortality in Late Life
Investigators: Richard G. Wight, Ph.D. and Carol S. Aneshensel, Ph.D.
Project Description: Investigate contextual effects of neighborhood socioeconomic status (SES) on mortality among older adults using the Asset and Health Dynamics Among Older Adults (AHEAD) study of 1993 and 1995. This is done by estimating the magnitude of between-neighborhood variation in mortality, and the extent of which this variation persists net of differences in the social status of the people who live in these different neighborhoods.

Title: Evaluating Fast Decay of Iconic Memory as an Early Sign for Alzheimer Disease
Investigators: Zhong-Lin Lu and Linda Clark
Project Description: This study is to follow subjects longitudinally to determine whether fast decay of iconic memory predicts later development of AD by comparing iconic (visual) sensory memory and attention in older adults with normal cognition to those with mild cognitive impairment (MCI). The hypothesis is that whether the difference in iconic memory can accurately predict cognitive status. These psychophysical measures will be compared to standard neuropsychological cognitive assessments scores and to changes in those scores over the previous year, to determine whether iconic memory correlates with lower current scores, and declines in scores, on standard cognitive tests.

Title: Feelings of Usefulness and Disability and Mortality Outcomesin the MacArthur Study of Successful Aging: Psychosocial, Behavioral and Physiological Pathways
Investigators: Tara L. Gruenewald
Project Description: This project is investigating whether feelings of usefulness to others is associated with the likelihood of disability development and mortality using the MacArthur Study of Successful Aging (MSSA). This study examines depression, physical and social activity, and indicators of low-grade inflammation (IL6 and CRP) as mediators associated with feeling useful.

Title: New Longitudinal Analyses of the Hawaii Family Study of Cognition
Investigators: John J. McArdle
Project Description: The purpose of this research is to recover and organize the database from the Hawaii Family Study of Cognition (HFSC) so that these classical data can be used in new longitudinal research to study a variety of contemporary dynamic propositions about aging, health and cognitive abilities.

Title: Longitudinal Analysis of Race/Ethnic and SES Differences in Allostatic Load among Midlife Women
Investigators: Dawn M. Upchurch, Ph.D. and Gail A. Greendale, M.D.
Project Description: This project will characterize the distribution of allostatic load (AL) and its consequences for important health markers (vascular stiffness and bone density) among a longitudinal sample of midlife women as well as the impact of demographic factors, personal coping strategies, spirituality, and social support of the accumulation of AL and its consequences on vascular stiffness and bone density using the data from the Study of Women’s Health Across the Nation (SWAN).

Title: C-reactive Protein and Blood Spots in Indonesia
Investigators: Elizabeth Frankenberg and Duncan Thomas, UCLA; laboratory work by Thomas McDade, Northwestern
Project Description: The first goal of this pilot project is to provide new evidence on the feasibility of using DBS to measure C-Reactive Protein (CRP), an indicator of acute inflammation and possibly a risk factor for coronary artery disease. The second goal of the project is to provide a careful and comprehensive characterization of the socio-demographic and health factors that are correlated with CRP.
The analyses will combine detailed SES and health information in the WISE study, a random assignment treatment-control intervention study in Indonesia, and identify those characteristics of individuals and their families that are predictive of elevated CRP. The results of this pilot study will provide the foundation for a research application which will include measurement of CRP using the DBS collected from all adult respondents in WISE as well as follow-up interviews three years after the DBS were collected. These measures of CRP will be used to predict subsequent heart disease, other health problems and mortality and will thereby provide unparalleled opportunities to more fully interpret the information contained in CRP in low income settings.

Title: Inflammation and Metabolic Risk and the Aging Process: Diet, Disease, and Development
Investigators: Hillard Kaplan, University of New Mexico
Project Description: This project has obtained and prepared a number of existing data sets that have information on markers of inflammation and cardiovascular and metabolic risk factors as well as indicators of physiological capacity such as height and weight, grip strength, stunting, etc. We are investigating these factors across the age range for populations living under very different conditions. We include populations from the United States, Mexico, and the Tsimane of Bolivia. Such populations have very different disease structures, economic status, expenditures of energy, nutritional status, and medical treatment. They have very different levels of both childhood and adult mortality and causes of morbidity. The aim of this project is to develop pilot data that will be used to prepare a program project. The use of physiological indicators from this variety of environments will provide the basis for pathbreaking work in biodemography.
This project tests the hypothesis that disease exposure, diet, and intervention experienced in childhood have a lasting effect on the aging process. The effect of the increasing societal development including better public health, diet, and health care has been to delay the aging process. Reductions in exposure to infections and noxious environments in childhood have left cohorts of older persons progressively healthier because they have been exposed to lower lifetime levels of inflammation. Improvements in sanitation and public health have resulted in more resistant hosts through decreases in exposure to bacteria and parasites.

Title: Education as a Modifier of Rate of Change among those with Memory Complaints and Mild Cognitive Dysfunction
Investigators: Margaret Gatz, Wendy Mack, Helena Chui, Carol McCleary, Caleb Finch, Eileen Crimmins
Project Description: The long run purpose of this study is to evaluate the protective effect of education and other indicators of mental ability or "mental exercise" against cognitive decline. The pilot research examined whether education relates to the timing of shifts from nondemented to mild cognitive impairment and from mild cognitive impairment to dementia, and from diagnosed dementia to death. The hypothesis is that people with higher education will drop faster once they start to decline, because their education protected them from crossing a diagnostic threshold for longer than would be the case for someone less endowed. Thus we would expect that having greater cognitive reserve will protect against onset of clinically diagnosed dementia, while decline after diagnosis will be more abrupt. The work of the pilot project is to develop the data from the ADRC files for such examination and test our ability to use the latent growth curve method with these data. This project will help us evaluate the role of changing educational levels in producing trends in population cognitive ability. This project was the basis of a section of a P01 project.

Title: Allostatic load, and telomere length, an index of cell aging
Principal Investigator: Teresa Seeman, Ph.D.
Other Investigators: Elissa Epel, Ph.D., Richard Cawthon, Ph.D.
Project Description : The aim of this project is to determine whether there is a link between telomere length and morbidity among a sample of older persons and to link psychosocial and demographic variables to telomere length. The pilot project will support data production. It will lead to a proposal for further research on the role of telomeres in predicting health outcomes. This study is measuring telomere length of white blood cells for the 900 subjects in the MacArthur Study who have blood samples archived from baseline, around 7.5 years earlier. It will examine whether telomere length predicts cardiovascular related diseases and morbidity (from death certificates) and possible relations with allostatic load, which is already linked to cognitive decline, morbidity, or mortality, in the MacArthur Aging Study. Lastly, as a secondary aim, we will explore how antioxidants, and psychosocial factors linked to neuroendocrine reactivity or morbidity, including socio-economic status, depression, and social support are linked to telomere length.

Title: Race/Ethnic Differences in Years of Potential Life Lost
Project Investigator: Susan Ettner and Mitchell Wong
Project Description: This study analyzed data from the National Health Interview Survey (NHIS) with linked vital statistics data to build a descriptive simulation model of mortality among Black, Latino, Asian and White adults. We first calculated all-cause and cause-specific mortality rates. We then examined mortality among Asians for only the more common causes of death given the more limited sample size of this ethnic group in the NHIS dataset. These rates were then used in a simlulation model to estimate racial/ethnic differences in years of potential life lost (YPLL). The specific aims of this study were to: 1) Estimate all-cause and cause-specific mortality rates for Whites, Blacks, Hispanics and Asians, standardized to the age and sex distribution of the U.S. population: 2) Conduct a simulation model using the mortality rate estimates in order to project the racial/ethnic differences in YPLL; 3) Calculate mortality rates adjusted for education, years lived in the U.S., obesity and smoking and incorporate these estimates into the simulation model, in order to predict the impact of these variables on racial/ethnic differences in YPLL.
Results: In this study, we found that African-Americans have higher mortality rates from a wide range of causes, however the disparity is concentrated in a few areas. HIV contributed most to the difference in YPLL (20.0%), followed by homicide (6.9%), hypertension (5.8%) and ischemic heart disease (4.8%). In fact, HIV accounted for a greater proportion of the racial disparity in YPLL than ischemic heart disease, cerebrovascular stroke, hypertension and congestive heart failure combined.
Dr. Wong has submitted a proposal for a K award to extend this work in several ways. First, the previous study examined years of life lost over an average follow-up period of 7.4 years. The proposed work will use a simulation model to estimate the life years lost over a lifetime. The simulation model will also allow the estimation the racial disparity in years of life lost due to differences in incidence vs. fatality from specific diseases. Thirdly, the simulation model would serve as a policy tool to estimate the impact of future interventions targeting the elimination of racial disparities in health. Finally, the proposed project will estimate the difference in cause-specific mortality for Latinos and Asians compared to Whites.

Title: The Genetics of Aging and Mortality of the Yeast S. Cerevisiae
Investigator: Valter Longo
Specific Aims: Analysis of age-specific mortality rates can provide a measure of the rate of aging and can enhance our understanding of the mechanisms underlying aging and death. The goal of this research is to study the age-specific mortality of populations of billions of long-lived and control yeast. These studies will be performed in parallel with measurements to assess age-dependent deteriorative physiological changes that lead to loss of function and death.
Findings: This study found that long-term, multiphasic mortality rates in yeast populations are highly reproducible, both within and across genotypes. Replicate cohorts show striking consistency throughout the lifespan, which reached over 120 days in some instances. The complicated dynamics are not a result of random variation (P<0.0001, P<0.005 for the null hypotheses that the log-mortality patterns are flat or linearly increasing, respectively). The multiphasic mortality patterns may be truly reflective of the underlying biology of the organism, such that physiological changes over time cause the risk of death in individual yeast to fluctuate. Observed mortality patterns might be due to a changing frailty of the individual organisms caused by the byproducts of respiration (e.g., oxidative damage) or by other physiological effects of aging. This hypothesis predicts that other physiological characters, such as stress resistance, would also exhibit multiphasic behavior.
The mutations that extend life in a variety of species appear to cause the organisms to be resistant to damage from heat and the corrosive effects of antioxidants. Extended longevity of these simple organisms appears to be associated with increased investment in maintenance and repair, sometimes at the expense of the growth rate. These findings could have important implications for the treatment of diseases. If drugs can be developed that make human cells younger and more resistant to multiple stresses – as in the long-lived organisms – then longevity would be extended and human cells would be protected against a variety of diseases.

Title: Ethnic/Education Differences in Cognitive Performance among Women in Five Ethnic Groups
Investigators: Galen Buckwalter, Gail Greendale, Teresa Seeman
Project Description: This project funded initial analyses of cognitive data from the multi-site, multi-ethnic Study of Women's Health Across the Nation (SWAN). This is a study of menopause, focusing on ethnic variations through inclusion of cohorts of Hispanic, African American, Japanese American and Chinese American women, in addition to Caucasians. We project funded pilot analyses exploring ethnic variation in cognitive performance and its relationship to differences in educational attainment. These analyses are designed to provide some preliminary, cross-sectional data on which an R01 application was based for additional funding to obtain longitudinal cognitive data for the SWAN cohort (something that is currently not included in the planned SWAN data collections).
Outcomes and Future Plans: This project provides the basis for requesting longitudinal data on cognition in future waves of SWAN. Research findings will be written up in the coming months.

Title: Education/Cognition and APOE
Investigators: Philip Bretsky, Teresa Seeman, Eileen Crimmins
Specific Aims: While perhaps the most general genetic risk factor currently described for the development of late-onset Alzheimer Disease, the effects of e4 allele of the Apolipoprotein E (APOE) gene on cognitive functioning more generally remain unclear. Cognitive decline in elderly persons is an early predictor of dementia and risks may be modified by a genetic predisposition. Multiple measures of cognitive function were assessed longitudinally in the MacArthur Successful Aging Study, a population-based cohort free of frank impairment at baseline. Subjects were 965 Caucasian and African-American men and women - from Durham NC, East Boston MA, and New Haven CT, aged 70-79, recruited in 1988-1989, and completed two follow-up evaluations, one at 3 years and another at 7 years.
Results: At the first follow-up, modest but significant declines in naming and spatial ability were associated with APOE-e4 genotype. By the second follow-up, more pronounced and significant associations were noted between APOE-e4 genotype and cognitive decline from six of the eight cognitive outcomes. After 7 years, APOE-e4 allele carriers were twice as likely to have declined on a global cognitive score (OR=2.0; 95%CI: 1.1, 3.6) as compared to non-carriers. This study shows that the APOE-e4 is associated with cognitive decline among a high-functioning elderly cohort with effects most pronounced after 7 years of follow-up. Hence, the e4 allele either may function as a risk factor for cognitive impairment in normal aging across a broad spectrum of domains or, alternatively, may exert detectable effects early in a long prodromal AD trajectory.
Outcomes and Future Work: A paper, “The role of apoe-e4 in longitudinal cognitive decline: MacArthur studies of successful aging,” has been submitted to Neurology. Further work on the role of education is underway.

Title: Measurement of Cognition
Investigators: Elizabeth Zelinski and Michael Gilewski
Specific Aims: To determine whether demographic and health variables differentially interact to predict cognitive scores in Asset and Health Dynamics of the Oldest-old (AHEAD), a nationally representative survey of older Americans to test the developmental discontinuity hypothesis. This research examined cognition in older adults across a variety of measures and used modern scaling methods to identify patterns of cross-sectional decline across measures, to evaluate the role of educational attainment in cross-sectional age differences and in longitudinal decline across cognitive abilities, and to determine whether change in some abilities is more differentially affected by educational attainment than in other abilities. This work used both the Long Beach longitudinal Study and the AHEAD data sets.
Methods: Rasch modeling procedures were used to rescale cognitive measures in AHEAD to calibrate interval scores from raw scores, equating scales across measures, making it possible to compare directly effects of predictors. It also reduces the likelihood of obtaining spurious interactions. Tasks included combined immediate and delayed recall, the Telephone Interview for Cognitive Status (TICS), Series 7, and an overall cognitive score.
Results: Direct comparisons of predictors across Rasch scales showed that demographic variables most strongly predicted performance on all scores, with health variables having smaller effects. Age interacted with both demographic and health variables, but patterns varied across variables. Demographic variables have strong effects on cognition. The developmental discontinuity hypothesis that health variables have stronger effects than demographic ones in cognition in the oldest-old was not supported.
Outcomes and Future work: A paper “Effects of Demographic and Health Variables on Rasch Scaled Cognitive Scores” has been submitted and a grant proposal is in the planning stages.

Title: Education, Occupation, and Cognitive Impairment: The Study of Dementia in Swedish Twins
Investigators: Margaret Gatz, Nancy Pedersen, Boo Johansson
Specific Aims: The purpose of this study was to examine whether education and intellectual engagement earlier in life are associated with cognitive impairment later. A co-twin control design was used in order to control for genetic and other familial influences. 167 twin pairs were included in the study in which one member was clinically demented while the twin partner was cognitively intact. These discordant pairs were identified from the Study of Dementia in Swedish Twins and the OCTO-Twin Study, subsamples from the population-based Swedish Twin Registry.
Results: Results from this research have been reported in two articles. The first is an analysis of education. The association between dementia and education was studied in 143 twin pairs discordant for dementia, using a matched pair design, and in 221 dementia cases and 442 unrelated controls from the same twin registry, using a case control design. Low education was defined as 6 years or less of schooling. Case control analyses with prevalent cases showed low education to be a risk for Alzheimer's disease but not dementia in general. Low education did not significantly predict incident cases. In the matched pairs analysis, which controls for genetic and other familial influences, differences in education between demented twins and twin partners were not statistically significant. However, for Alzheimer's disease, odds ratios resulting from matched pairs and case control analyses were similar. Twins' comparative reports about intellectual involvement earlier in their lives suggest a longstanding difference on this dimension, with less involvement by the twin who will become demented. This research is reported in the following article:

Gatz, M. Svedberg, P., Pederson, N.L., Mortimer, J.A., Berg, S., & Johansson, B. (2001). Education and the risk of Alzheimer’s disease: Findings from the Study of Dementia in Swedish Twins, Journals of Gerontology: Psychological Sciences, 56, P292-P300.

The second study examined whether an active lifestyle affects risk of Alzheimer’s disease: specifically, whether participation in leisure activities during early and middle adulthood was associated with reduced subsequent risk of Alzheimer’s disease and dementia in general. The study sample consisted of 107 same-sex twin pairs discordant for dementia for whom information on leisure activities was self-reported more than 20 years prior to clinical evaluation. A factor analysis of these activities yielded three activity factors: intellectual-cultural, self-improvement and domestic activity. Matched pair analyses compared activities within the discordant twin pairs while controlling for level of education. Odds ratios adjusted for level of education revealed that, within twin pairs, participation in a greater overall number of leisure activities was associated with lower risk of both Alzheimer’s disease (OR=.5, 95% CI=0.3-1.0) and dementia in general (OR=0.6, 95% CI=0.4-1.0).
The association between overall activity level and Alzheimer’s disease was significant for women (OR=0.4, 95% CI=0.2-0.8) but not for men (OR=1/1, 95% CI=0.4-3.4). In addition, greater engagement in intellectual –cultural activities was associated with lower risk of Alzheimer’s disease for women (OR=0.4, 95% CI=0.2-1.0), although not for men (OR=0.9, 95% CI=0.3-2.6). Thus, within twin pairs, those who reported participating in more leisure activities than their siblings were less likely to develop Alzheimer’s disease or any type of dementia. Social and intellectual activities may be more important for dementia. This was presented as a paper at GSA and is presently under review:

Crowe, M., Andel, R., Gatz, M. & Pederson, N.L. Leisure activities and dementia: A co-twin control study.

Future Plans: This project has provided the foundation for future work and a future grant submission.