Prevalence of essential tremor in a multiethnic, community-based study in northern Manhattan, New York, N.Y.

Our aims were to: (1) estimate the prevalence of essential tremor (ET) in a community-based study in northern Manhattan, New York, N.Y., USA; (2) compare prevalence across ethnic groups, and (3) provide prevalence estimates for the oldest old. Methods: This study did not rely on a screening questionnaire. Rather, as part of an in-person neurological evaluation, each participant produced several handwriting samples, from which ET diagnoses were assigned. Results: There were 1,965 participants (76.7 ± 6.9 years, range = 66–102 years); 108 had ET [5.5%, 95% confidence interval (CI) = 4.5–6.5%]. Odds of ET were robustly associated with Hispanic ethnicity versus white ethnicity [odds ratio (OR) = 2.19, 95% CI = 1.03–4.64, p = 0.04] and age (OR = 1.14, 95% CI = 1.03–1.26, p = 0.01), i.e. with every 1 year advance in age, the odds of ET increased by 14%. Prevalence reached 21.7% among the oldest old (age ≥95 years). Conclusions: This study reports a significant ethnic difference in the prevalence of ET. The prevalence of ET was high overall (5.5%) and rose markedly with age so that in the oldest old, more than 1 in 5 individuals had this disease

Steady-state MreB helices inside bacteria: dynamics without motors

Within individual bacteria, we combine force-dependent polymerization dynamics of individual MreB protofilaments with an elastic model of protofilament bundles buckled into helical configurations. We use variational techniques and stochastic simulations to relate the pitch of the MreB helix, the total abundance of MreB, and the number of protofilaments. By comparing our simulations with mean-field calculations, we find that stochastic fluctuations are significant. We examine the quasi-static evolution of the helical pitch with cell growth, as well as timescales of helix turnover and denovo establishment. We find that while the body of a polarized MreB helix treadmills towards its slow-growing end, the fast-growing tips of laterally associated protofilaments move towards the opposite fast-growing end of the MreB helix. This offers a possible mechanism for targeted polar localization without cytoplasmic motor proteins.Comment: 7 figures, 1 tabl

Use and Cost of Hospitalization in Dementia: Longitudinal Results from a Community-Based Study

OBJECTIVES: The aim of this study is to examine the relative contribution of functional impairment and cognitive deficits on risk of hospitalization and costs. METHODS: A prospective cohort of Medicare beneficiaries aged 65 and older who participated in the Washington Heights-Inwood Columbia Aging Project (WHICAP) were followed approximately every 18 months for over 10 years (1805 never diagnosed with dementia during study period, 221 diagnosed with dementia at enrollment). Hospitalization and Medicare expenditures data (1999-2010) were obtained from Medicare claims. Multivariate analyses were conducted to examine (1) risk of all-cause hospitalizations, (2) hospitalizations from ambulatory care sensitive (ACSs) conditions, (3) hospital length of stay (LOS), and (4) Medicare expenditures. Propensity score matching methods were used to reduce observed differences between demented and non-demented groups at study enrollment. Analyses took into account repeated observations within each individual. RESULTS: Compared to propensity-matched individuals without dementia, individuals with dementia had significantly higher risk for all-cause hospitalization, longer LOS, and higher Medicare expenditures. Functional and cognitive deficits were significantly associated with higher risks for hospitalizations, hospital LOS, and Medicare expenditures. Functional and cognitive deficits were associated with higher risks of for some ACS but not all admissions. CONCLUSIONS: These results allow us to differentiate the impact of functional and cognitive deficits on hospitalizations. To develop strategies to reduce hospitalizations and expenditures, better understanding of which types of hospitalizations and which disease characteristics impact these outcomes will be critical

An Association between Head Circumference and Alzheimer's Disease in a Population-Based Study of Aging and Dementia

We investigated the association between head circumference (HC) and Alzheimer's disease (AD) in a cross-sectional population-based study of aging in North Manhattan. Six hundred forty-nine subjects underwent neurologic, neuropsychological, and anthropometric evaluations; apolipoprotein E (apoE) genotype was available for a subsample of 300 individuals. Logistic regression analyses were performed with AD the outcome of interest to evaluate any association between HC and AD. In these analyses, HC evaluated as a continuous variable was associated with AD (OR 0.8, 95% CI 0.7-0.9) after adjusting for age, education, and ethnicity, gender, and height. Analyses suggested that increased risk resided mainly in those with smallest HC. Thus, women whose HC was within the lowest quintile of HC for women were 2.9 (95% CI 1.4-6.1) times more likely to have AD, after adjusting for age, education, and ethnicity; and men in the lowest quintile of HC (for men) were 2.3 times more likely to have AD (95% CI 0.6-9.8). There was no confounding by height, weight, or apoE genotype. The results are consistent with previous studies that suggest that premorbid brain size may influence the age-specific risk for AD. Future epidemiologic studies seeking environmental risk factors for AD may benefit by making HC measurements on all subjects to decrease the variance associated with other potential risk factors

Primary Care Expenditures before the Onset of Alzheimer's Disease

Objective: To investigate primary care expenditures in the period before diagnosis of AD. Methods: In a population-based sample of Medicare enrollees in New York City, person-level 1996 Medicare claims, summed over primary care encounters, were examined for people who developed AD in 1997 to 1998 and those who did not. Results: People who developed AD were more likely to use Medicare outpatient and ambulatory care 1 to 2 years before diagnosis. Compared with respondents who did not develop AD, the excess cost for men was $1,167 (85$239 (26% higher). Among elderly people ≥75 years in the United States, the prodromal period of AD was associated with an excess Medicare-based primary care cost of $128.5 to$194.7 million. Conclusion: In addition to huge costs associated with AD after diagnosis, prediagnosis costs are an unrecognized source of expenditures related to the disease

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

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

Diagnosis of Dementia in a Heterogeneous Population: A Comparison of Paradigm-Based Diagnosis and Physician's Diagnosis

Each of 430 subjects received a diagnosis using two independent methods: a test-based quantitative paradigm and a semistructured neurological examination by a physician. The paradigm diagnosis was based on a battery of tests that assessed short- and long-term verbal memory and shortterm nonverbal memory, orientation, construction, abstract reasoning, and language. The subjects came from a community in Manhattan County, in New York City, and were characterized by diversity with respect to both ethnicity (29.1% black, 33.4% Hispanic) and educational level (23.5% with 6 or fewer years of education, 25.6% college educated). Based on the paradigm, 10.5% of subjects received diagnoses of dementia, 29.1% of cognitive impairment, and 60.5% of normal. Based on the physician's diagnosis, 9.8% were demented, 21.6% cognitively impaired, and 68.6% normal. There was agreement between the two diagnostic methods for 71.8% of subjects. Diagnostic disagreement (n=121) was in most cases between normal and cognitively impaired (71.0%) or between cognitively impaired and demented (21.5%). There were only nine cases (7.5%) in which a subject was judged demented by one method and normal by the other. The reliability of each method with respect to the other was moderate (intraclass correlation coefficient,.62), while the reliability of a composite diagnosis based on both methods was much higher (.77). The paradigm was more likely than the physician to give the diagnosis of dementia to patients with low educational levels. The physician's diagnosis was strongly influenced by measures of functioning and by the mental status test administered in the semistructured neurological examination. Race and diagnosis were not related when the effect of education was controlled. Strengths and potential weaknesses of each method of diagnosis, and the relationship between education and diagnosis, are discussed

Prenatal Insecticide Exposures and Birth Weight and Length among an Urban Minority Cohort

We reported previously that insecticide exposures were widespread among minority women in New York City during pregnancy and that levels of the organophosphate chlorpyrifos in umbilical cord plasma were inversely associated with birth weight and length. Here we expand analyses to include additional insecticides (the organophosphate diazinon and the carbamate propoxur), a larger sample size (n = 314 mother–newborn pairs), and insecticide measurements in maternal personal air during pregnancy as well as in umbilical cord plasma at delivery. Controlling for potential confounders, we found no association between maternal personal air insecticide levels and birth weight, length, or head circumference. For each log unit increase in cord plasma chlorpyrifos levels, birth weight decreased by 42.6 g [95% confidence interval (CI), −81.8 to −3.8, p = 0.03] and birth length decreased by 0.24 cm (95% CI, −0.47 to −0.01, p = 0.04). Combined measures of (ln)cord plasma chlorpyrifos and diazinon (adjusted for relative potency) were also inversely associated with birth weight and length (p < 0.05). Birth weight averaged 186.3 g less (95% CI, −375.2 to −45.5) among newborns with the highest compared with lowest 26% of exposure levels (p = 0.01). Further, the associations between birth weight and length and cord plasma chlorpyrifos and diazinon were highly significant (p ≤ 0.007) among newborns born before the 2000–2001 U.S. Environmental Protection Agency’s regulatory actions to phase out residential use of these insecticides. Among newborns born after January 2001, exposure levels were substantially lower, and no association with fetal growth was apparent (p > 0.8). The propoxur metabolite 2-isopropoxyphenol in cord plasma was inversely associated with birth length, a finding of borderline significance (p = 0.05) after controlling for chlorpyrifos and diazinon. Results indicate that prenatal chlorpyrifos exposures have impaired fetal growth among this minority cohort and that diazinon exposures may have contributed to the effects. Findings support recent regulatory action to phase out residential uses of the insecticides