Privacy Concerns and Information Sharing: The Perspective of the U-Shaped Curve.

Privacy concerns are a key predictor of information sharing, yet some critical issues remain unclear. Based on social capital theory, this study argues that the relationship between privacy concerns and information sharing is a U-shaped curve. Users with privacy concerns would not share their private information; however, such users would eventually share their information as long as they trust the website and its members. Furthermore, this study provides a contingency perspective, suggesting that the curvilinear relationship between privacy concerns and information sharing varies with the system evaluation perception and personal motivation levels. The results show that at a high level of system evaluation, the relationship between privacy concerns squared and information sharing is non-significant. In contrast, at a low level of system evaluation, there is a U-shaped relationship between privacy concerns and information sharing. Regarding motivation, the results were congruent with our expectations.

[From Peritoneal Dialysis Education Guidelines to Clinical Practice].

Peritoneal dialysis (PD) education, which has been shown to impact life quality and survival rates, is thus crucial to patients with end-stage renal disease. As medical workers in the PD field, it is our hope and obligation to lead every patient to achieve their individual self-care goals. Although the International Society of Peritoneal Dialysis (ISPD) published guidelines for peritoneal dialysis training in 2006 to help build a comprehensive educational program for better outcomes, how to implement related education programs has not yet been taken seriously by clinical health workers. In Taiwan, no articles introducing these guidelines and no report on the clinical implementation of these guidelines have been published. Thus, this article was written to describe the ISPD guidelines on PD education, including education content, space requirements, soft / hard equipment needs, training hours, and mode. Medical workers may use evaluation and periodical retraining to continuously monitor the self-care ability of patients. Aided by timely home visitations, learning outcomes and patient adaption may be followed comprehensively. Furthermore, to help patients under PD strengthen their capabilities of self-management and self-care, practical training suggestions based on the practice experience of our PD center are also included in this article as references for all medical workers in the PD field.

A latent class approach for joint modeling of a time-to-event outcome and multiple longitudinal biomarkers subject to limits of detection.

Multiple biomarkers on different biological pathways are often measured over time to investigate the complex mechanism of disease development and progression. Identification of informative subpopulation patterns of longitudinal biomarkers and clinical endpoint may assist in risk stratification and provide insights into new therapeutic targets. Motivated by a multicenter study to assess the inflammatory markers of sepsis in patients with community-acquired pneumonia, we propose a joint latent class analysis of multiple biomarkers and a time-to-event outcome while accounting for censored biomarker measurements due to detection limits. The interrelationship between biomarker trajectories and clinical endpoint is fully captured by a latent class structure, which reveals the subpopulation profiles of biomarkers and clinical outcome. The estimation of joint latent class models becomes more complicated when biomarkers are subject to detection limits. Based on a Metropolis-Hastings method, we develop a Monte Carlo Expectation-Maximization (MCEM) algorithm to estimate model parameters. We demonstrate the satisfactory performance of our MCEM algorithm using simulation studies, and apply our method to the motivating study to examine the heterogeneous patterns of cytokine responses to pneumonia and associated mortality risks.

The association between pulse pressure change and cognition in late life: Age and where you start matters.

INTRODUCTION: Variations across studies in the association between blood pressure (BP) and cognition might be explained partly by duration of exposure to hypertension and partly by nonrandom attrition over time. Pulse pressure (PP) reflects arterial stiffness which may better reflect chronicity of hypertension. METHODS: Over six annual cycles, 1954 individuals aged 65+ years from a prospective population-based cohort underwent BP measurements and cognitive evaluations. We examined the relationship of change in five cognitive domains to longitudinal PP patterns across the late-life age spectrum, before and after stratifying by baseline systolic blood pressure (SBP) and adjusting for attrition. RESULTS: There were four longitudinal PP patterns: stable normal, stable high, increasing, and decreasing. Those with lower baseline SBP and an increasing or stable high PP had less decline in cognition, an effect that was attenuated with aging. Among those with higher baseline SBP, there were no differences across PP groups, but increasing age was consistently associated with greater cognitive decline. DISCUSSION: The effect of PP on cognitive decline depends on age, baseline SBP, and the trajectory of PP change. Cardiovascular mechanisms underlying cognitive aging should be recognized as nuanced and dynamic processes when exploring prevention and treatment targets in the elderly, so that the optimal timing and type of intervention can be identified.

Independent and combined effects of cognitive and physical activity on incident MCI.

INTRODUCTION: The objective of this study was to examine the independent and combined influences of late-life cognitive activity (CA) and physical activity (PA) on the risk of incident mild cognitive impairment (MCI). METHODS: We used interval censored survival modeling to examine the risk of incident MCI (Clinical Dementia Rating [CDR] = 0.5) as a function of CA (high vs. low) and at least moderate intensity PA (any vs. none) among 864 cognitively normal (CDR = 0) older adults. RESULTS: During three annual follow-up waves, 72 participants developed MCI. Compared with low CA with no PA, significant reductions in risk for MCI were observed for high CA with any PA (hazards ratio (HR) = 0.20, 95% confidence interval (CI) 0.07-0.52) and low CA with any PA (HR = 0.52, 95% CI 0.29-0.93), but not for high CA without PA (HR = 0.94, 95% CI 0.45-1.95). DISCUSSION: These findings suggest that a combination of CA and PA may be most efficacious at reducing the risk for cognitive impairment.

Rates and risk factors for progression to incident dementia vary by age in a population cohort.

OBJECTIVE: To estimate rate of progression from normal cognition or mild impairment to dementia, and to identify potential risk and protective factors for incident dementia, based on age at dementia onset in a prospective study of a population-based cohort (n = 1,982) aged 65 years and older. METHODS: Following the cohort annually for up to 5 years, we estimated incidence of dementia (Clinical Dementia Rating ≥1) among individuals previously normal or mildly impaired (Clinical Dementia Rating 0 or 0.5). In the whole cohort, and also stratified by median onset age, we examined several vascular, metabolic, and inflammatory variables as potential risk factors for developing dementia, using interval-censored survival models. RESULTS: Based on 67 incident cases of dementia, incidence rate (per 1,000 person-years) was 10.0 overall, 5.8 in those with median onset age of 87 years or younger, and 31.5 in those with onset age after 87 years. Adjusting for demographics, the risk of incident dementia with onset age of 87 years or younger (n = 33) was significantly increased by baseline smoking, stroke, low systolic blood pressure, and APOE*4 genotype, and reduced by current alcohol use. Among those with dementia with onset after 87 years (n = 34), no risk or protective factor was significant. CONCLUSION: Risk and protective factors were only found for incident dementia with onset before the median onset age of 87 years, and not for those with later onset. Either unexplored risk factors explain the continued increase in incidence with age, or unknown protective factors are allowing some individuals to delay onset into very old age.

Who wants a free brain scan? Assessing and correcting for recruitment biases in a population-based sMRI pilot study.

Neuroimaging research is usually conducted in volunteers who meet a priori selection criteria. Selection/volunteer bias is assumed but cannot be assessed. During an ongoing population-based cohort study of 1982 older adults, we asked 1702 active participants about their interest in undergoing a research brain scan. Compared with those not interested, the 915 potentially interested individuals were significantly younger, more likely to be male, better educated, generally healthier, and more likely to be cognitively intact and dementia-free. In 48 of the interested individuals, we conducted a previously reported pilot structural magnetic resonance imaging (sMRI) study modelling mild cognitive impairment (MCI) vs. normal cognition, and Clinical Dementia Rating (CDR) = 0.5 vs. CDR = 0, as a function of sMRI atrophy ratings. We now compare these 48 individuals (1) with all interested participants, to assess selection bias; (2) with all who had been asked about their interest, to assess volunteer bias; and (3) with the entire study cohort, to assess attrition bias from those who had dropped out before the question was asked. Using these data in propensity score models, we generated weights which we applied to logistic regression models reanalyzing the data from the pilot sMRI study. These weighted models adjusted, in turn, for selection bias, interest/volunteer bias, and attrition bias. They show fewer regions of interest to be associated with MCI/ CDR than were in the original unweighted models. When study participants are drawn from a well-characterized population, they can be compared with non-participants, and the information used to correct study results for potential bias and thus provide more generalizable estimates.

How well do MCI criteria predict progression to severe cognitive impairment and dementia?

BACKGROUND: The International Working Group (IWG) criteria for mild cognitive impairment have variable utility in predicting progression to dementia, partly depending on the setting. We explored an empiric approach to optimize the criteria and cutoff points in a population study. METHODS: In a cohort of adults aged 65 years or older, we identified 1129 individuals with normal or only mildly impaired cognition by cognitive classification, and 1146 individuals without dementia (Clinical Dementia Rating <1). Operationally defining the IWG criterion set, we examined its sensitivity and specificity for the development of severe cognitive impairment and dementia (Clinical Dementia Rating ≥1) over 4 years. We then disaggregated the criteria and used Classification and Regression Tree analyses to identify the optimal predictive model. RESULTS: The operational IWG criteria had 49% sensitivity and 86% specificity for the outcome of severe cognitive impairment, and 40% sensitivity and 84% specificity for the outcome of dementia. Classification and Regression Tree modeling improved sensitivity to 82% for the cognitive outcome and 76% for the dementia outcome; specificity remained high. Memory scores were the most important predictors for both outcomes. The optimal cutoff points were around 1.0 SD below the age-education mean. The best fit was observed when prediction was modeled separately for each age-education group. CONCLUSIONS: Objective cognitive measurements contributed more to the prediction of dementia than subjective and functional measures. Those with less education only required memory testing, whereas those with more education required assessment of several cognitive domains. In cases in which only overall norms are available, the appropriate threshold will vary according to the individual's age and education.

Cohort effects in age-associated cognitive trajectories.

BACKGROUND: The age-specific prevalence and incidence of dementia and cognitive impairment in the United States have either remained stable or even slightly declined during the 1980s-1990s. A suggested but untested reason for this improvement in cognitive function over time is higher educational attainment among more recent cohorts. METHODS: We used data from two large prospective population-based epidemiological dementia studies conducted in two adjacent regions during the period 1987-2012. We examined whether (i) cohort effects could be observed in age-associated trajectories of cognitive functions and (ii) the observed cohort effects could be explained by educational attainment. Trajectories of neuropsychological tests tapping three domains (psychomotor speed, executive function, and language) were compared among cohorts born between 1902 and 1911, 1912 and 1921, 1922 and 1931, and 1932 and 1943. We examined Age × Cohort interactions in mixed-effects models with/without controlling for education effects. RESULTS: Cohort effects in age-associated trajectories were observed in all three domains, with consistent differences between the earliest born cohort and the most recent cohort. Executive functions showed the strongest and persistent differences between the most recent and other three cohorts. Education did not attenuate any of these associations. CONCLUSIONS: Cohort effects were observed in all examined cognitive domains and, surprisingly, remained significant after controlling for educational effects. Factors other than education are likely responsible for the cohort effects in cognitive decline.

Clinical and demographic covariates of chronic opioid and non-opioid analgesic use in rural-dwelling older adults: the MoVIES project.

BACKGROUND: To describe covariates and patterns of late-life analgesic use in the rural, population-based MoVIES cohort from 1989 to 2002. METHODS: Secondary analysis of epidemiologic survey of elderly people conducted over six biennial assessment waves. Potential covariates of analgesic use included age, gender, depression, sleep, arthritis, smoking, alcohol, and general health status. Of the original cohort of 1,681, this sample comprised 1,109 individuals with complete data on all assessments. Using trajectory analysis, participants were characterized as chronic or non-chronic users of opioid and non-opioid analgesics. Multivariable regression was used to model predictors of chronic analgesic use. RESULTS: The cohort was followed for mean (SD) 7.3 (2.7) years. Chronic use of opioid analgesics was reported by 7.2%, while non-opioid use was reported by 46.1%. In the multivariable model, predictors of chronic use of both opioid and non-opioid analgesics included female sex, taking ≥2 prescription medications, and "arthritis" diagnoses. Chronic opioid use was also associated with age 75-84 years; chronic non-opioid use was also associated with sleep continuity disturbance. CONCLUSIONS: These epidemiological data confirm clinical observations and generate hypotheses for further testing. Future studies should investigate whether addressing sleep problems might lead to decreased use of non-opioid analgesics and possibly enhanced pain management.

Survival of septic adults compared with nonseptic adults receiving extracorporeal membrane oxygenation for cardiopulmonary failure: a propensity-matched analysis.

PURPOSE: Limited data on the outcomes of adults with active sepsis undergoing extracorporeal membrane oxygenation (ECMO) exist. MATERIALS AND METHODS: We analyzed our prospective database for adults undergoing their first ECMO from 2001 to 2009. Patients with preexisting sepsis had newly emerging or uncontrolled infections precipitating refractory respiratory and/or circulatory failure within 7 days preceding ECMO. Propensity score matching was performed to equalize potential prognostic factors between patients with and patients without sepsis. RESULTS: Of the 514 adults receiving their first ECMO, 108 with preexisting sepsis were matched with 108 without sepsis by propensity score. Overall survival to discharge did not differ between those with (28.7%) and those without sepsis (37.0%; P = .192). When venovenous ECMO and venoarterial ECMO were considered separately, survival tended to be worse for septic patients on venoarterial ECMO (24.4%) compared with nonseptic adults on venoarterial ECMO (34.9%; P = .147). After adjustments for age, stroke, acute myocarditis, inter-extracorporeal cardiopulmonary resuscitation, and post-ECMO renal and neurologic deficits by multivariate analysis, the increased risk of mortality persisted for septic adults receiving venoarterial ECMO (hazard ratio, 2.54; 95% confidence intervals, 1.75-3.70; P < .01). Patients on venovenous ECMO had similar outcomes regardless of preexisting sepsis. CONCLUSIONS: Preexisting sepsis is not a contraindication for ECMO. However, venoarterial ECMO should be used with caution, given active sepsis.

Light and the outcome of the critically ill: an observational cohort study.

INTRODUCTION: Light before and during acute illness has been associated with both benefit and harm in animal models and small human studies. Our objective was to determine the associations of light duration (photoperiod) and intensity (insolation) before and during critical illness with hospital mortality in ICU patients. Based on the 'winter immunoenhancement' theory, we tested the hypothesis that a shorter photoperiod before critical illness is associated with improved survival. METHODS: We analyzed data from 11,439 patients admitted to 8 ICUs at the University of Pittsburgh Medical Center between June 30, 1999 and July 31, 2004. Daily photoperiod and insolation prior to and after ICU admission were estimated for each patient by using data provided by the United States Naval Observatory and National Aeronautics and Space Administration and direct measurement of light gradient from outside to bedside for each ICU room. Our primary outcome was hospital mortality. The association between light and risk of death was analyzed using multivariate analyses, adjusting for potential confounders, including severity of illness, case mix, and ICU type. RESULTS: The cohort had an average APACHE III of 52.9 and a hospital mortality of 10.7%. In total, 128 ICU beds were analyzed; 108 (84%) had windows. Pre-illness photoperiod ranged from 259 to 421 hours in the prior month. A shorter photoperiod was associated with a reduced risk of death: for each 1-hour decrease, the adjusted OR was 0.997 (0.994 to 0.999, p = 0.03). In the ICU, there was near complete (99.6%) degradation of natural light from outside to the ICU bed. Thus, light exposure once in the ICU approached zero; the 24-hour insolation was 0.005 ± 0.003 kWh/m² with little diurnal variation. There was no association between ICU photoperiod or insolation and mortality. CONCLUSIONS: Consistent with the winter immunoenhancement theory, a shorter photoperiod in the month before critical illness is associated with a reduced risk of death. Once in the ICU, patients are exposed to near negligible natural light despite the presence of windows. Further studies are warranted to determine the underlying mechanisms and whether manipulating light exposure, before or during ICU admission, can enhance survival.

Cross-validation of brain structural biomarkers and cognitive aging in a community-based study.

BACKGROUND: Population-based studies face challenges in measuring brain structure relative to cognitive aging. We examined the feasibility of acquiring state-of-the-art brain MRI images at a community hospital, and attempted to cross-validate two independent approaches to image analysis. METHODS: Participants were 49 older adults (29 cognitively normal and 20 with mild cognitive impairment (MCI)) drawn from an ongoing cohort study, with annual clinical assessments within one month of scan, without overt cerebrovascular disease, and without dementia (Clinical Dementia Rating (CDR) < 1). Brain MRI images, acquired at the local hospital using the Alzheimer's Disease Neuroimaging Initiative protocol, were analyzed using (1) a visual atrophy rating scale and (2) a semi-automated voxel-level morphometric method. Atrophy and volume measures were examined in relation to cognitive classification (any MCI and amnestic MCI vs. normal cognition), CDR (0.5 vs. 0), and presumed etiology. RESULTS: Measures indicating greater atrophy or lesser volume of the hippocampal formation, the medial temporal lobe, and the dilation of the ventricular space were significantly associated with cognitive classification, CDR = 0.5, and presumed neurodegenerative etiology, independent of the image analytic method. Statistically significant correlations were also found between the visual ratings of medial temporal lobe atrophy and the semi-automated ratings of brain structural integrity. CONCLUSIONS: High quality MRI data can be acquired and analyzed from older adults in population studies, enhancing their capacity to examine imaging biomarkers in relation to cognitive aging and dementia.

Smoking, death, and Alzheimer disease: a case of competing risks.

If smoking is a risk factor for Alzheimer disease (AD) but a smoker dies of another cause before developing or manifesting AD, smoking-related mortality may mask the relationship between smoking and AD. This phenomenon, referred to as competing risk, complicates efforts to model the effect of smoking on AD. Typical survival regression models assume that censorship from analysis is unrelated to an individual's probability for developing AD (ie, censoring is noninformative). However, if individuals who die before developing AD are younger than those who survive long enough to develop AD, and if they include a higher percentage of smokers than nonsmokers, the incidence of AD will appear to be higher in older individuals and in nonsmokers. Further, age-specific mortality rates are higher in smokers because they die earlier than nonsmokers. Therefore, if we fail to take into account the competing risk of death when we estimate the effect of smoking on AD, we bias the results and are in fact only comparing the incidence of AD in nonsmokers with that in the healthiest smokers. In this study, we demonstrate that the effect of smoking on AD differs in models that are and are not adjusted for competing risks.

[A needs assessment of nursing staff AIDS care knowledge needs].

BACKGROUND: The number of HIV infections in Taiwan has been increasingly linear in recent years. At the close of April 2009, Taiwan registered 17, 979 AIDS infections. The average annual infection rate has grown an average 18% during the most recent five year period. Apart from medical problems, the social and psychological problems associated with AIDS are becoming increasingly complicated both in Taiwan and globally with the increasing number of HIV infections. Identifying the knowledge needs of nursing staff members for providing appropriate nursing care to HIV/AIDS patients is important to planning effective in-service nursing education programs. Quality of both patient care and professional development can be promoted. PURPOSE: This study investigated the HIV/AIDS educational needs of nursing staffs and variations in care knowledge needs by individual background. Results provide a reference for in-service education program planners. METHODS: This was a descriptive and correlational study design that used self-structured questionnaires to conduct a cross-sectional survey. A total of 556 structural questionnaires were distributed and 546 completed questionnaires were returned (response rate = 98.2%) and used in data analysis. RESULTS: The average knowledge need score for nursing staffs with regard to HIV/AIDS patient care was > 4 points. The highest three mean scores were (in rank order): follow-up treatment for victims after sexual assault, prevention of injury (e.g., sharp objects, exposure to infected body fluids) and subsequent management, and nursing care of opportunistic infection. The lowest three mean scores were (in rank order): HIV epidemiology, Taiwan HIV policies and regulations, and HIV transmission routes. Nurses who were older, married, or held senior nurse positions had more knowledge needs. CONCLUSION: This study can be a reference for prioritizing the arrangement of in-service HIV/AIDS care education and for formulating hospital policies related to HIV/AIDS patients. Prevention of injury and subsequent management of patients with opportunistic infections should be made mandatory in all health care provider courses. Also, enhancing promotion of safety needles can help reduce needle stick risks for clinical staff.

Outcomes of mild cognitive impairment by definition: a population study.

BACKGROUND: Mild cognitive impairment (MCI) has been defined in several ways. OBJECTIVE: To determine the 1-year outcomes of MCI by different definitions at the population level. DESIGN: Inception cohort with 1-year follow-up. Participants were classified as having MCI using the following definitions operationalized for this study: amnestic MCI by Mayo criteria, expanded MCI by International Working Group criteria, Clinical Dementia Rating (CDR) = 0.5, and a purely cognitive classification into amnestic and nonamnestic MCI. SETTING: General community. PARTICIPANTS: Stratified random population-based sample of 1982 individuals 65 years and older. MAIN OUTCOME MEASURES: For each MCI definition, there were 3 possible outcomes: worsening (progression to dementia [CDR ≥ 1] or severe cognitive impairment), improvement (reversion to CDR = 0 or normal cognition), and stability (unchanged CDR or cognitive status). RESULTS: Regardless of MCI definition, over 1 year, a small proportion of participants progressed to CDR > 1 (range, 0%-3%) or severe cognitive impairment (0%-20%) at rates higher than their cognitively normal peers. Somewhat larger proportions of participants improved or reverted to normal (6%-53%). Most participants remained stable (29%-92%). Where definitions focused on memory impairment and on multiple cognitive domains, higher proportions progressed and lower proportions reverted on the CDR. CONCLUSIONS: As ascertained by several operational definitions, MCI is a heterogeneous entity at the population level but progresses to dementia at rates higher than in normal elderly individuals. Proportions of participants progressing to dementia are lower and proportions reverting to normal are higher than in clinical populations. Memory impairments and impairments in multiple domains lead to greater progression and lesser improvement. Research criteria may benefit from validation at the community level before incorporation into clinical practice.

Infections occurring during extracorporeal membrane oxygenation use in adult patients.

OBJECTIVE: The application of extracorporeal membrane oxygenation in adults has been increasing, but infections occurring during extracorporeal membrane oxygenation use are rarely described. METHODS: We retrospectively analyzed the prospectively collected data on nosocomial infection surveillance of 334 patients aged 16 years or more undergoing their first extracorporeal membrane oxygenation for more than 48 hours at a university hospital from 1996 to 2007 for respiratory (20.4%) and cardiac (79.6%) support. RESULTS: During a total of 2559 extracorporeal membrane oxygenation days, 55 episodes of infections occurred in 45 patients (13.5%), including 38 bloodstream (14.85 per 1000 extracorporeal membrane oxygenation days), 6 surgical site, 4 respiratory tract, 3 urinary tract, and 4 other infections. Stenotrophomonas maltophilia (16.7%) and Candida species (14.6%) were the predominant blood isolates. In stepwise logistic regression analysis, longer duration of extracorporeal membrane oxygenation use (odds ratio 1.003; 95% confidence interval, 1.001-1.005; P = .004), mechanical complications (odds ratio, 4.849; 95% confidence interval, 1.569-14.991; P = .006), autoimmune disease (odds ratio, 6.997; 95% confidence interval, 1.541-31.766; P = .012), and venovenous mode (odds ratio, 4.473; 95% confidence interval, 1.001-19.977; P = .050) were independently associated with a higher risk for infections during extracorporeal membrane oxygenation use. Overall in-hospital mortality was 68.3%, and its independent risk factors included older age (odds ratio, 1.037; 95% confidence interval, 1.021-1.054; P < .001), neurologic complications (odds ratio, 51.153; 95% confidence interval, 6.773-386.329; P < .001), and vascular complications (odds ratio, 1.922; 95% confidence interval, 1.112-3.320; P < .001), but not infections during extracorporeal membrane oxygenation use. CONCLUSIONS: Bloodstream infection was the most common infection during extracorporeal membrane oxygenation use. Duration of extracorporeal membrane oxygenation, mechanical complications, autoimmune disease, and venovenous mode seemed to be independently associated with infections.

Cognitive test performance predicts change in functional status at the population level: the MYHAT Project.

In the community at large, many older adults with minimal cognitive and functional impairment remain stable or improve over time, unlike patients in clinical research settings, who typically progress to dementia. Within a prospective population-based study, we identified neuropsychological tests predicting improvement or worsening over 1 year in cognitively driven everyday functioning as measured by Clinical Dementia Rating (CDR). Participants were 1682 adults aged 65+ and dementia-free at baseline. CDR change was modeled as a function of baseline test scores, adjusting for demographics. Among those with baseline CDR = 0.5, 29.8% improved to CDR = 0; they had significantly better baseline scores on most tests. In a stepwise multiple logistic regression model, tests which remained independently associated with subsequent CDR improvement were Category Fluency, a modified Token Test, and the sum of learning trials on Object Memory Evaluation. In contrast, only 7.1% with baseline CDR = 0 worsened to CDR = 0.5. They had significantly lower baseline scores on most tests. In multiple regression analyses, only the Mini-Mental State Examination, delayed memory for visual reproduction, and recall susceptible to proactive interference, were independently associated with CDR worsening. At the population level, changes in both directions are observable in functional status, with different neuropsychological measures predicting the direction of change.

Prevalence of mild cognitive impairment by multiple classifications: The Monongahela-Youghiogheny Healthy Aging Team (MYHAT) project.

OBJECTIVES: To estimate and compare the frequency and prevalence of mild cognitive impairment (MCI) and related entities using different classification approaches at the population level. DESIGN: Cross-sectional epidemiologic study of population-based cohort recruited by age-stratified random sampling from electoral rolls. SETTING: Small-town communities in western Pennsylvania. PARTICIPANTS: Of 2,036 individuals aged 65 years and older, 1,982 participants with normal or mildly impaired cognition (age-education-corrected Mini-Mental State scores ≥ 21). MEASUREMENTS: Demographics, neuropsychological assessment expressed as cognitive domains, functional ability, and subjective reports of cognitive difficulties; based on these measurements, operational criteria for the Clinical Dementia Rating (CDR) scale, the 1999 criteria for amnestic MCI, the 2004 Expanded criteria for MCI, and new, purely cognitive criteria for MCI. RESULTS: A CDR rating of 0.5 (uncertain/very mild dementia) was obtained by 27.6% of participants, whereas 1.2% had CDR ≥ 1 (mild or moderate dementia). Among those with CDR <1, 2.27% had amnestic MCI and 17.66% had expanded MCI, whereas 35.17% had MCI by purely cognitive classification. Isolated executive function impairment was the least common, whereas impairment in multiple domains including executive function was the most common. Prevalence estimates weighted against the U.S. Census are also provided. CONCLUSIONS: The manner in which criteria for MCI are operationalized determines the proportion of individuals who are thus classified and the degree of overlap with other criteria. Prospective follow-up is needed to determine progression from MCI to dementia and thus empirically develop improved MCI criteria with good predictive value.

Age and education effects and norms on a cognitive test battery from a population-based cohort: the Monongahela-Youghiogheny Healthy Aging Team.

OBJECTIVES: Performance on cognitive tests can be affected by age, education, and also selection bias. We examined the distribution of scores on several cognitive screening tests by age and educational levels in a population-based cohort. METHOD: An age-stratified random sample of individuals aged 65+ years was drawn from the electoral rolls of an urban US community. Those obtaining age and education-corrected scores > or = 21/30 on the Mini-Mental State Examination (MMSE) were designated as cognitively normal or only mildly impaired, and underwent a full assessment including a battery of neuropsychological tests. Participants were also rated on the Clinical Dementia Rating (CDR) scale. The distribution of neuropsychological test scores within demographic strata, among those receiving a CDR of 0 (no dementia), are reported here as cognitive test norms. After combining individual test scores into cognitive domain composite scores, multiple linear regression models were used to examine associations of cognitive test performance with age and education. RESULTS: In this cognitively normal sample of older adults, younger age and higher education were associated with better performance in all cognitive domains. Age and education together explained 22% of the variation of memory, and less of executive function, language, attention, and visuospatial function. CONCLUSION: Older age and lesser education are differentially associated with worse neuropsychological test performance in cognitively normal older adult representatives of the community at large. The distribution of scores in these participants can serve as population-based norms for these tests, and can be especially useful to clinicians and researchers assessing older adults outside specialty clinic settings.