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Open Access Publications from the University of California

Scholarly Works (63 results)

  • Article
  • Peer Reviewed
UC San Francisco Previously Published Works (2015)
Dementia is a major cause of disability and death among older adults. Those with type 2 diabetes (T2D) are 50-100% more likely to develop dementia than those without T2D, but it is unknown whether this association reflects a causal relationship. Proposed mechanisms through which T2D could cause dementia include the effects of insulin dysregulation and chronic hyperglycemia on features of Alzheimer's disease and macrovascular and microvascular disorders in the brain. More research is needed to elucidate the link between T2D and dementia and identify strategies to maintain cognitive function among people with T2D.
    Cover page: Diabetes and Cognition
    • Thesis
    • Peer Reviewed
    UC San Francisco Electronic Theses and Dissertations (2013)

    Type 2 diabetes is highly prevalent and has been linked with an increased risk of dementia and premature mortality. Earlier death among people with diabetes may impact the association between diabetes and dementia. This is particularly important for populations with a high burden of diabetes, including Mexican Americans and African Americans. The objective of this dissertation was to evaluate the association of diabetes with incidence of dementia and cognitive impairment without dementia (CIND) and cognitive decline in late-life among Mexican Americans and in mid-life among African Americans and whites while accounting for the competing risk of mortality. The study populations included: 1) a cohort of dementia-free older Mexican Americans (n=1617) aged 60-98 from the Sacramento Area Latino Study on Aging (SALSA) followed for 10 years beginning in 1998 and 2) a cohort of middle-aged African Americans and whites (n=1886) aged 48-70 from the Atherosclerosis Risk in Communities (ARIC) Study followed for 14 years beginning in 1990. The association between diabetes and incidence of dementia/CIND was examined with competing risk regression models in the SALSA cohort and the association between diabetes and cognitive decline was examined with joint longitudinal-survival models in the SALSA and ARIC cohorts. In the SALSA cohort, Mexican Americans with treated and untreated diabetes had an increased risk of dementia/CIND compared to those without diabetes (HR=2.05, 95% CI: 1.41-2.97 and HR=1.55, 95% CI: 0.93-2.58) after accounting for the competing risk of death. Additionally, Mexican Americans with diabetes experienced modestly accelerated cognitive decline compared to those without diabetes. In the ARIC cohort, earlier onset of diabetes was associated with greater cognitive decline in mid-life among African Americans. No association between diabetes and cognitive decline was observed among whites. These findings provide evidence that the association between diabetes and dementia/CIND among Mexican Americans remains strong after accounting for the competing risk of mortality. The association between diabetes and cognitive decline is less evident. Future research is needed to identify how diabetes treatments influence cognitive decline among people with diabetes.

      Cover page: Type 2 Diabetes, Risk of Dementia and Cognitive Decline, and the Competing Risk of Mortality Among Middle-Aged and Older Adults
      • Thesis
      • Peer Reviewed
      UCLA Electronic Theses and Dissertations (2023)

      Gold-standard clinical dementia adjudication is resource intensive and infeasible in large, population-representative studies which are critical for public health research. Algorithmic dementia classification uses models to predict cognitive impairment and was developed to circumvent challenges of the gold-standard adjudication process. Several algorithms have been developed to classify dementia in the Health and Retirement Study (HRS) and rely on information in the Aging, Demographics, and Memory Study (ADAMS), a substudy of HRS initiated in 2001. Existing algorithms cannot incorporate neuropsychological measures as they are unavailable in HRS, and models cannot be adapted to include more comprehensive measures available in newer studies.I propose a novel Bayesian latent class mixture modeling framework for algorithmic dementia classification that incorporates information from neuropsychological measures and can be adapted to include more comprehensive measures available in updated studies. The model uses latent class mixture models to create synthetic versions of datasets, incorporating information on relationships between sociodemographic, health, and cognitive measures and cognitive impairment classes through prior distributions based on studies with gold-standard adjudicated cases. This work involves three studies on aging: The Health and Retirement Study (HRS), The Harmonized Cognitive Assessment Protocol (HCAP, HRS substudy), and the Aging and Demographics Study (ADAMS, HRS substudy). Simulation studies were conducted to evaluate the role of study sample size and priors specified based on different data sources and sampling frames and their impact on algorithmic dementia classification results and inferences on racial/ethnic differences in dementia. Analyses using priors from ADAMS accurately captured cognitive impairment classes preserved racial/ethnic differences in dementia for Black vs. White participants. Priors better calibrated to the analytic sample however improved estimates for Black and Hispanic participants and preserved racial/ethnic differences in dementia for Black vs. White and Hispanic vs. White participants. Applying the model to HCAP 2016 yielded reasonable estimates of cognitive impairment classes with proportions of impaired participants in line with findings published by HCAP investigators. This dissertation lays important groundwork for strengthening algorithmic dementia classification in population-representative studies. Outcomes from this work are directly applicable to existing studies on AD/ADRD that are harmonizable with HRS/HCAP.

        Cover page: Link, transport, integrate: a Bayesian latent class mixture modeling framework for scalable algorithmic dementia classification in population-representative studies
        • Article
        • Peer Reviewed
        UC Davis Previously Published Works (2019)

        Background

        Posttraumatic stress disorder is associated with increased dementia risk but less is known about stress because of everyday problems in diverse populations.

        Methods

        A total of 9605 health care plan members who provided information regarding midlife stressors in 1972 to 1973 (ages, 40 to 55 y) were followed for dementia diagnosis between 1996 and 2017. Cox proportional hazard models evaluated associations between midlife stressors and dementia adjusting for demographics and lifecourse health indicators.

        Results

        Reporting at least 1 midlife stressor was associated with 17% greater dementia risk [hazard ratio (HR), 1.17; 95% confidence interval (CI),1.07-1.27] versus 0 midlife stressors and 26% increased risk among those with less than equal to high school education (HR, 1.26; 95% CI,1.09-1.44) adjusting for demographics. Compared with whites without stressors, whites with ≥1 stressor had 13% greater dementia risk (HR, 1.13; 95% CI, 1.02-1.24), blacks without stressors 19% greater risk (HR, 1.19; 95% CI,1.08-1.32), and blacks with ≥1 stressors 47% greater risk (HR, 1.47; 95% CI,1.27-1.69) in fully adjusted models. Resource problems were associated with 20% greater risk (HR, 1.20; 95% CI, 1.01-1.42) than interpersonal problems.

        Conclusion

        Reporting ≥1 serious midlife stressor was associated with elevated dementia risk, especially stressors related to resources problems and for those with less than equal to high school education. Everyday stressors can impact brain health over the long term and may contribute to racial inequities in dementia rates, though education can be a mitigating factor.
          Cover page: Stressors in Midlife and Risk of Dementia
          • Article
          • Peer Reviewed
          UC San Francisco Previously Published Works (2013)

          Objective

          We examined whether acculturation and immigrant generation, a marker for assimilation, are associated with diabetes risk in an aging Mexican origin population.

          Methods

          We analyzed data on 1789 adults aged 60 to 101 years from the Sacramento Area Latino Study on Aging. We ascertained type 2 diabetes on the basis of diabetic medication use, self-report of physician diagnosis, or a fasting glucose of 126 milligrams/deciliter or greater. Logistic regression modeled prevalent diabetes.

          Results

          Adjusting for age and gender, we observed significant but divergent associations between immigrant generation, acculturation, and diabetes risk. Relative to first-generation adults, second-generation adults had an odds ratio (OR) of 1.8 (95% confidence interval [CI] = 1.4, 2.4) and third-generation adults had an OR of 2.1 (95% CI = 1.4, 3.1) of having diabetes. Greater US acculturation, however, was associated with a slightly decreased diabetes rate. In the full model adjusting for socioeconomic and lifestyle factors, the association between generation (but not acculturation) and diabetes remained significant.

          Conclusions

          Our study lends support to the previously contested notion that assimilation is associated with an increased diabetes risk in Mexican immigrants. Researchers should examine the presence of a causal link between assimilation and health more closely.
            Cover page: [Immigrant generation and diabetes risk among Mexican Americans: the Sacramento Area Latino Study on Aging].
            • Article
            • Peer Reviewed
            UC San Francisco Previously Published Works (2013)

            Objectives

            We examined whether acculturation and immigrant generation, a marker for assimilation, are associated with diabetes risk in an aging Mexican-origin population.

            Methods

            We analyzed data on 1789 adults aged 60 to 101 years from the Sacramento Area Latino Study on Aging. We ascertained type 2 diabetes on the basis of diabetic medication use, self-report of physician diagnosis, or a fasting glucose of 126 milligrams/deciliter or greater. Logistic regression modeled prevalent diabetes.

            Results

            Adjusting for age and gender, we observed significant but divergent associations between immigrant generation, acculturation, and diabetes risk. Relative to first-generation adults, second-generation adults had an odds ratio (OR) of 1.8 (95% confidence interval [CI] = 1.4, 2.4) and third-generation adults had an OR of 2.1 (95% CI = 1.4, 3.1) of having diabetes. Greater US acculturation, however, was associated with a slightly decreased diabetes rate. In the full model adjusting for socioeconomic and lifestyle factors, the association between generation (but not acculturation) and diabetes remained significant.

            Conclusions

            Our study lends support to the previously contested notion that assimilation is associated with an increased diabetes risk in Mexican immigrants. Researchers should examine the presence of a causal link between assimilation and health more closely.
              Cover page: Immigrant generation and diabetes risk among Mexican Americans: the Sacramento Area Latino Study on Aging.
              • Article
              • Peer Reviewed
              UC San Francisco Previously Published Works (2017)

              Objective

              To determine whether physical activity and body mass index (BMI) predict instrumental or basic activities of daily living (I/ADL) trajectories before or after stroke compared to individuals who remained stroke-free.

              Methods

              Using a prospective cohort, the Health and Retirement Study, we followed adults without a history of stroke in 1998 (n = 18,117) for up to 14 years. We estimated linear regression models of I/ADL trajectories comparing individuals who remained stroke-free throughout follow-up (n = 16,264), those who survived stroke (n = 1,374), and those who died after stroke and before the next interview wave (n = 479). We evaluated whether I/ADL trajectories differed by physical activity or BMI at baseline (before stroke), adjusting for demographic and socioeconomic covariates.

              Results

              Compared to those who were physically active, stroke survivors who were physically inactive at baseline had a lower probability of independence in ADLs and IADLs 3 years after stroke (risk difference = -0.18 and -0.16 for ADLs and IADLs, respectively). However, a similar difference in the probability of independence was also present 3 years before stroke, and we observed no evidence that physical activity slowed the rate of decline in independence before or after stroke. Unlike the results for physical activity, we did not observe a consistent pattern for the probability of independence in ADLs or IADLs comparing obese stroke survivors to normal-weight or to overweight stroke survivors 3 years before stroke or 3 years after stroke.

              Conclusions

              Physical inactivity predicts a higher risk of being dependent both before and after stroke.
                Cover page: Physical activity, but not body mass index, predicts less disability before and after stroke
                • Article
                • Peer Reviewed
                UC Davis Previously Published Works (2018)

                Background

                Poor pulmonary function (PPF) is associated with increased risk of dementia, yet it is unclear if PPF in early adulthood to midlife increases risk, independent of smoking and subsequent vascular disease.

                Objective

                This study evaluated the association between multiple markers of PPF in early adulthood to midlife and long-term risk of dementia.

                Methods

                We evaluated 27,387 members of an integrated health care system with forced expiratory volume in 1, 2 seconds, and vital capacity collected from 1964 to 1973 (mean age=41.8±4.2 y). Associations of PPF with dementia diagnoses from January 1, 1996 to September 30, 2015 were evaluated with Cox proportional hazards models adjusted for demographics, height, body mass index, hypertension, smoking status, diabetes, stroke, and heart failure.

                Results

                In total, 7519 individuals (27%) were diagnosed with dementia. In fully adjusted Cox proportional hazards models, for all PPF measures each liter decrease was associated with a 13% to 14% higher risk of dementia. Compared with the highest quintile, the first quintile of PPF measures were associated with a 24% to 28% increased risk of dementia; second to fourth quintiles showed strong dose-dependent associations. Results were similar when stratified by smoking status.

                Conclusions

                In this large, diverse cohort, multiple measures of PPF in early adulthood to midlife were associated with dementia risk independent of smoking and vascular comorbidities.
                  Cover page: Early Midlife Pulmonary Function and Dementia Risk
                  • Article
                  • Peer Reviewed
                  UCLA Previously Published Works (2021)

                  Purpose

                  Diabetes and depression are risk factors for cardiovascular disease, but the evidence about their interaction effect on long-term health outcomes among Latinos is lacking. We aimed to investigate the joint association of diabetes and subsequent depressive symptoms with mortality among older Latinos, an understudied racial/ethnic group with high prevalence of diabetes.

                  Methods

                  This study included 1,495 adults from the Sacramento Area Latino Study on Aging. We employed Cox proportional-hazards models to estimate the adjusted hazard ratios [aHRs] for cardiovascular and all-cause mortality according to diabetes status at enrollment and depressive symptoms a year after the enrollment. We used marginal structural models to adjust for time-varying confounders.

                  Results

                  The mean age (standard deviation) of participants was 70 (6.6) years. Over follow-up (median 7.7 years), diabetes and depressive symptoms were individually associated with increased risk of cardiovascular mortality (diabetes, aHR[95% CI]=2.13[1.60-2.84]; depressive symptoms, aHR[95% CI]=1.62[1.09-2.39]) and all-cause mortality (diabetes, aHR[95% CI]=1.92[1.53-2.41]; depressive symptoms, aHR[95% CI]=1.41[1.02-1.94]). After adjusting for time-varying confounders, we found a multiplicative interaction between diabetes and subsequent depressive symptoms for cardiovascular mortality (aHR[95% CI]=2.94[1.07-8.39]), but not all-cause mortality (aHR[95% CI]=1.80[0.81-4.35]).

                  Conclusions

                  Using a longitudinal cohort of community-dwelling older Latinos, we found that diabetes and subsequent depressive symptoms were jointly associated with increased risk of cardiovascular mortality.
                    Cover page: Estimating the joint effect of diabetes and subsequent depressive symptoms on mortality among older latinos
                    • Article
                    • Peer Reviewed
                    UC Davis Previously Published Works (2016)

                    Introduction

                    Reducing racial/ethnic disparities is a primary objective of the National Alzheimer's Plan (NAPA), yet direct comparisons within large samples representing diversity of the United States are lacking.

                    Methods

                    Dementia incidence from January 1, 2000 to December 31, 2013 and a 25-year cumulative risk in 274,283 health care members aged 64+ (n = 18,778 African-American, n = 4543 American Indian/Alaska Native [AIAN], n = 21,000 Latino, n = 440 Pacific Islander, n = 206,490 white, n = 23,032 Asian-Americans). Cox proportional hazard models were adjusted for age, sex, medical utilization, and comorbidities.

                    Results

                    Dementia incidence (n = 59,555) was highest for African-Americans (26.6/1000 person-years) and AIANs (22.2/1000 person-years); intermediate for Latinos (19.6/1000 person-years), Pacific Islanders (19.6/1000 person-years), and whites (19.3/1000 person-years) and lowest among Asian-Americans (15.2/1000 person-years). Risk was 65% greater for African-Americans (hazard ratio = 1.65; 95% confidence interval = 1.58-1.72) versus Asian-Americans. Cumulative 25-year risk at age 65 was as follows: 38% African-Americans, 35% AIANs, 32% Latino, 25% Pacific Islanders, 30% white, and 28% Asian-Americans.

                    Discussion

                    Dementia rates varied over 60% between groups, providing a comprehensive benchmark for the NAPA goal of reducing disparities.
                      Cover page: Inequalities in dementia incidence between six racial and ethnic groups over 14 years
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