[show abstract][hide abstract] ABSTRACT: Cognitive lifestyle measures such as education, occupation, and social engagement are commonly associated with late-life cognitive ability although their associations with cognitive decline tend to be mixed. However, longitudinal analyses of cognition rarely account for death and dropout, measurement error of the cognitive phenotype, and differing trajectories for different population sub-groups. This paper applies a joint latent class mixed model (and a multi-state model in a sensitivity analysis) that accounts for these issues to a large (n = 3,653), population-based cohort, Paquid, to model the relationship between cognitive lifestyle and cognitive decline. Cognition was assessed over a 20-year period using the Mini-Mental State Examination. Three cognitive lifestyle variables were assessed: education, mid-life occupation, and late-life social engagement. The analysis identified four latent sub-populations with class-specific longitudinal cognitive decline and mortality risk. Irrespective of the cognitive trajectory, increased social engagement was associated with a decreased mortality risk. High education was associated with the most favourable cognitive trajectory, and after adjusting for cognitive decline, with an increased mortality risk. Mid-life occupational complexity was also associated with more favourable trajectories but not with mortality risk. To realistically examine the link between cognitive lifestyle and cognitive decline, complex statistical models are required. This paper applies and compares in a sensitivity analysis two such models, and shows education to be linked to a compression of cognitive morbidity irrespective of cognitive trajectory. Furthermore, a potentially modifiable variable, late-life social engagement is associated with a decreased mortality risk in all of the population sub-groups.
European Journal of Epidemiology 02/2014; · 5.12 Impact Factor
[show abstract][hide abstract] ABSTRACT: A better knowledge of long-term trajectories of cognitive decline is a central feature of the study of the process leading to Alzheimer's dementia. Several factors may mitigate such decline, among which is education, a major risk factor for Alzheimer's disease. The aim of our work was to compare the pattern and duration of clinical trajectories before Alzheimer's dementia in individuals with low and high education within the PAQUID cohort involving 20 years of follow-up. The sample comprises 442 participants with incident Alzheimer's disease (27.2% were male)-171 with low education (mean age = 86.2 years; standard deviation = 5.3 years) and 271 with higher education (mean age = 86.5; standard deviation = 5.4)-and 442 control subjects matched according to age, sex and education. At each visit and up to the 20-year follow-up visit, several cognitive and clinical measures were collected and incident cases of Alzheimer's disease clinically diagnosed. The evolution of clinical measures in pre-demented subjects and matched controls was analysed with a semi-parametric extension of the mixed effects linear model. The results show that the first signs of cognitive decline occurred 15 to 16 years before achieving dementia threshold in higher-educated subjects whereas signs occurred at 7 years before dementia in low-educated subjects. There seemed to be two successive periods of decline in higher-educated subjects. Decline started ∼15 to 16 years before dementia with subtle impairment restricted to some cognitive tests and with no impact during the first 7 to 8 years on global cognition, cognitive complaints, or activities of daily living scales. Then, ∼7 years before dementia, global cognitive abilities begin to deteriorate, along with difficulties dealing with complex activities of daily living, the increase in self-perceived difficulties and depressive symptoms. By contrast, lower-educated subjects presented a single period of decline lasting ∼7 years, characterized by decline concomitantly affecting specific and more global cognitive function along with alteration in functional abilities. This study demonstrates how early cognitive symptoms may emerge preceding Alzheimer's dementia particularly in higher-educated individuals, for whom decline occurred up to 16 years before dementia. It also demonstrates the protective role of education in the clinical trajectory preceding Alzheimer's dementia. We suggest that the initial decline in cognition occurs at the onset of comparable Alzheimer's disease pathology in both groups, and is associated with immediate decline to dementia in the lower education group. In contrast, higher education protects against further cognitive decline for ∼7 years until pathology becomes more severe.
[show abstract][hide abstract] ABSTRACT: We aimed to investigate the impact of endogenous estradiol (E2) on dementia and to evaluate the contribution of vascular risk factors and inflammatory and blood coagulation markers to this association.
Using data from a French population-based prospective study (the Three-City Study) including 5,644 postmenopausal women aged 65 years or older, we investigated the association of endogenous total-E2 and bioavailable-E2 and total-testosterone with the 4-year incidence of all-cause dementia. We further focused on the role of dementia and cardiovascular risk factors as well as inflammation (C-reactive protein, fibrinogen) and hypercoagulability (fibrin d-dimers, thrombin generation) in these associations. We used a case-cohort design consisting of a random subcohort of 562 women not using hormone therapy and 132 incident dementia cases.
Adjusted Cox proportional hazards models showed a J-shaped relationship between total-E2 and risk of dementia (p = 0.001). Total-E2 values in the lower and upper quartiles were associated with an increased dementia risk (adjusted hazard ratio [HR] [95% confidence interval] = 2.2 [1.1-4.5] and HR = 2.4 [1.2-5.2], respectively). Importantly, the risk associated with higher E2 levels was dramatically increased in women with diabetes compared with nondiabetic women (adjusted HR associated with the upper E2 quartile = 14.2 [1.60-123] and HR = 3.4 [0.1-147], respectively, p interaction <0.05). Similar results were found for bioavailable-E2. Adjustment for inflammatory and blood coagulation markers did not modify our results. No significant association was found for total-testosterone.
High E2 level is an independent predictor of incident dementia, particularly in postmenopausal women with diabetes.
[show abstract][hide abstract] ABSTRACT: Structural alterations of a large network characterize Alzheimer's disease (AD), but the time course of these changes remains unclear. The dynamic of these alterations was examined in the AD preclinical phase using data from the 10-year follow-up of a population-based cohort (Bordeaux-3City).
Participants received neuropsychological assessments every 2 years and two identical magnetic resonance imaging (MRI) exams at baseline and 4 years later. Twenty-five incident AD cases were compared with 319 subjects who remained free of dementia. Subjects were free of dementia at baseline and at follow-up MRI. Incident AD occurred after these time points.
At baseline, incident AD already presented smaller volumes only in the left amygdalo-hippocampal complex. Moreover, a higher annual rate of atrophy of the temporoparietal cortices was observed in future AD subjects during the following 4 years.
Incident AD cases present mediotemporal lesions up to 5 years before diagnosis. This neurodegenerative process seems to progressively reach the temporoparietal cortices in the AD preclinical phase.
Alzheimer's & dementia: the journal of the Alzheimer's Association 01/2014; · 14.48 Impact Factor
[show abstract][hide abstract] ABSTRACT: Lipid metabolism and particularly high-density lipoprotein (HDL) may be involved in the pathogenic mechanism of age-related macular degeneration (AMD). However, conflicting results have been reported in the associations of AMD with plasma HDL and other lipids, which may be confounded by the recently reported associations of AMD with HDL-related genes. We explored the association of AMD with plasma lipid levels and lipid-lowering medication use, taking into account most of HDL-related genes associated with AMD.
The Alienor study is a population-based study on age-related eye diseases performed in 963 elderly residents of Bordeaux (France). AMD was graded from non mydriatic color retinal photographs in three exclusive stages: no AMD (n = 430 subjects, 938 eyes); large soft distinct drusen and/or large soft indistinct drusen and/or reticular drusen and/or pigmentary abnormalities (early AMD, n = 176, 247); late AMD (n = 40, 61). Associations of AMD with plasma lipids (HDL, total cholesterol (TC), Low-density lipoprotein (LDL), and triglycerides (TG)) were estimated using Generalized Estimating Equation logistic regressions. Statistical analyses included 646 subjects with complete data.
After multivariate adjustment for age, sex, educational level, smoking, BMI, lipid-lowering medication use, cardiovascular disease and diabetes, and for all relevant genetic polymorphisms (ApoE2, ApoE4, CFH Y402H, ARMS2 A69S, LIPC rs10468017, LIPC rs493258, LPL rs12678919, ABCA1 rs1883025 and CETP rs3764261), higher HDL was significantly associated with an increased risk of early (OR = 2.45, 95%CI: 1.54-3.90; P = 0.0002) and any AMD (OR = 2.29, 95%CI: 1.46-3.59; P = 0.0003). Association with late AMD was far from statistical significance (OR = 1.58, 95%CI: 0.48-5.17; p = 0.45). No associations were found for any stage of AMD with TC, LDL and TG levels, statin or fibrate drug use.
This study suggests that elderly patients with high HDL concentration may be at increased risk for AMD and, further, that HDL dysfunction might be implicated in AMD pathogenesis.
PLoS ONE 01/2014; 9(3):e90973. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Objective
The objective of this study is to compare cognitive decline of elderly people after entering an institution with that of elders living in the community with similar clinical conditions.
The Personnes Agées QUID (PAQUID) cohort is a prospective population-based study which included, at baseline, 3777 community-dwelling people aged 65 years and older. Participants were followed-up for 22 years. Among those who were nondemented and living at home at baseline, 2 groups were compared: participants who entered a nursing home during study follow-up (n = 558) and those who remained living at home (n = 3117). Cognitive decline was assessed with Mini-Mental State Examination (MMSE), Benton visual retention test, and verbal fluency Isaacs Set Test.
After controlling for numerous potential confounders, including baseline MMSE and instrumental activities of daily living scores, incident dementia, depressive symptoms, and chronic diseases, nursing home placement was significantly associated with a lower score on MMSE between the last visit before and after institutionalization (difference of 2.8 points, P < .0001) and greater further cognitive decline after institutionalization (difference of 0.7 point per year, P < .0001). Similar results were found for the Benton memory test. In a second series of analysis in which the persons who became demented over the study follow-up were excluded, the results remained unchanged.
The present study suggests that institutionalized elderly people present a greater cognitive decline than persons remaining in the community. The reasons of that decline remain unclear and may be related to physical and psychological effects of institutionalization in elderly people.
Journal of the American Medical Directors Association 01/2014; · 5.30 Impact Factor
[show abstract][hide abstract] ABSTRACT: Motivation
Diseases that progress slowly are often studied by observing cohorts at different stages of disease for short periods of time. The Alzheimer's Disease Neuroimaging Initiative (ADNI) follows elders with various degrees of cognitive impairment, from normal to impaired. The study includes a rich panel of novel cognitive tests, biomarkers, and brain images collected every 6 months for as long as 6 years. The relative timing of the observations with respect to disease pathology is unknown. We propose a general semiparametric model and iterative estimation procedure to estimate simultaneously the pathological timing and long-term growth curves. The resulting estimates of long-term progression are fine-tuned using cognitive trajectories derived from the long-term “Personnes Agées Quid” study.
We demonstrate with simulations that the method can recover long-term disease trends from short-term observations. The method also estimates temporal ordering of individuals with respect to disease pathology, providing subject-specific prognostic estimates of the time until onset of symptoms. When the method is applied to ADNI data, the estimated growth curves are in general agreement with prevailing theories of the Alzheimer's disease cascade. Other data sets with common outcome measures can be combined using the proposed algorithm.
Software to fit the model and reproduce results with the statistical software R is available as the grace package. ADNI data can be downloaded from the Laboratory of NeuroImaging.
Alzheimer's & dementia: the journal of the Alzheimer's Association 01/2014; · 14.48 Impact Factor
[show abstract][hide abstract] ABSTRACT: Background: Knowledge of functional evolution in dementia is crucial for the patients and their families and for clinician. Objective: This review identifies scales and outcomes used to describe the natural history of functional decline and describes the natural history of functional decline in a representative clinical and population sample of published studies of patients with Alzheimer's disease (AD). Methods: A search of three relevant databases was conducted and limited to articles published in English and French between 1998 to March 2012, using the keywords "Dementia", "Activities of Daily Living", "Instrumental Activities of Daily Living", "Functional Impairment", "Prognosis", and "Disease Progression". Results: The search strategy displayed 683 articles, 20 of which were found to be related to the functional evolution of AD. In these studies, different scales were used to describe the evolution of the functional decline, except for the decline of instrumental activities, for which the Lawton scale was used in all studies. Thus, it is difficult to represent the evolution of the functional decline from a clinical point of view. Conclusion: Relatively little data are available to estimate the functional evolution of AD. A consensus with broaden thought is required to know if the progression of the incapacities in these scales is additive or hierarchical.
Journal of Alzheimer's disease: JAD 12/2013; · 4.17 Impact Factor
[show abstract][hide abstract] ABSTRACT: To validate a rapid questionnaire as a screening tool, because application of the diagnostic revised criteria of the ICHD-II for medication overuse headache (MOH) requires experience for the physician and is time-consuming.
ICHD-II criteria for probable MOH (pMOH) were transformed in questions formulated in such a way that they could be self-administered, easily understood, and quickly filled out. We compared this questionnaire to the gold standard: the diagnosis made by headache specialists, based on the the ICHD-II criteria. Patients who were consulting for pMOH or migraine for the first time were consecutively included. As validity indicators, we calculated sensitivity, specificity, positive and negative predictive values of the items.
Seventy-nine patients were screened, 77 included, 2 female patients excluded. Forty-two patients have been considered as suffering from pMOH, 35 patients suffered from migraine without medication overuse. The association of the question "do you take a treatment for attacks more than 10 days per month" and the question "is this intake on a regular basis?" had a sensitivity of 95.2% and a specificity of 80%.
This screening tool can detect pMOH with a sensitivity that could be of interest to screen patients in clinical practice and to pre-include patients for research as epidemiological studies.
The Journal of Headache and Pain 10/2013; 14(1):81. · 2.78 Impact Factor
[show abstract][hide abstract] ABSTRACT: The objective of this study was to examine the association of plasma estradiol and testosterone with risk for dementia in elderly men.
Within the population based Three-City study, including 3650 men age 65 years and older, a case-cohort design was set up after 4-years of follow-up. Baseline plasma levels of total 17-β estradiol (Total-E2), total testosterone (total-T) and bioavailable testosterone (bio-T) were measured for all cases of incident dementia (n = 105) and for a random sample of the cohort (n = 413). Cox regression models were used to estimate multivariate steroid sex hormone-associated hazard ratios (HR) and 95% confidence intervals of dementia.
There was a reverse J-shaped relationship between total-T and risk for dementia (P = .007). Compared with the median tertile, the HRs associated with total-T in the lower and upper tertile were increased (HR, 2.33; P = .026; HR, 1.9, P = .126; respectively). Low bio-T was associated with a greater risk for dementia (HR for one standard deviation of decreasing log(bio-T), 1.29; 95% confidence interval, 1.03-1.62). An interaction was found between bio-T and age (P < .0001), and bio-T and education (P = .044). Risk for dementia associated with low bio-T was greater in older men (80 years or older) than in younger men (younger than 80 years; HR, 3.11; P = .011 vs. HR, 1.07, P = .715, respectively) and in men with high level of education compared with those with low level of education (HR, 2.32; P = .0002 vs. HR, 0.95; P = .790, respectively). No significant association was found between Total-E2 and dementia.
Low levels of testosterone are associated with a risk for dementia in elderly men. The association between low bio-T and dementia may be more relevant to men 80 years or older and men with a high level of education.
Alzheimer's & dementia: the journal of the Alzheimer's Association 09/2013; · 14.48 Impact Factor
[show abstract][hide abstract] ABSTRACT: The relationship between blood pressure and dementia is incompletely understood in elderly individuals. Blood pressure variability may have a role in the risk of dementia.
This investigation was a cohort study of 6506 elderly individuals followed-up for 8 years (1999-2001 through 2008) with assessments at years 2, 4, and 7-8. Blood pressure was measured by electronic devices at baseline and at 2- and 4-year follow-up examinations. Cox proportional hazard models adjusted for potential confounders were used to estimate the risk of incident dementia according to blood pressure (means and coefficients of variation of the three measures).
During the 40,151 person-years of follow-up 474 participants developed dementia. We observed no association between mean blood pressure and risk of dementia. In contrast, an increase of 1 standard deviation in the coefficient of variation of blood pressure was associated with a 10% increased risk of dementia. Analysis by deciles of the coefficient of variation showed that the higher the variability, the higher the risk of dementia (P < .02 for trend). In the fully adjusted Cox model, the risk of dementia for those in the highest decile of the coefficient of variation of systolic blood pressure was 1.77 (1.17-2.69) compared with the lowest decile.
In this cohort study, variability of blood pressure during follow-up was associated with an increased risk of incident dementia, whereas mean blood pressure was not. Limitation of blood pressure fluctuation may be an important target to preserve cognitive function in the elderly.
Alzheimer's & dementia: the journal of the Alzheimer's Association 08/2013; · 14.48 Impact Factor
[show abstract][hide abstract] ABSTRACT: To quantify the ability of a marker to predict the onset of a clinical outcome in the future, time-dependent estimators of sensitivity, specificity, and ROC curve have been proposed accounting for censoring of the outcome. In this paper, we review these estimators, recall their assumptions about the censoring mechanism and highlight their relationships and properties. A simulation study shows that marker-dependent censoring can lead to important biases for the ROC estimators not adapted to this case. A slight modification of the inverse probability of censoring weighting estimators proposed by Uno et al. (2007) and Hung and Chiang (2010a) performs as well as the nearest neighbor estimator of Heagerty et al. (2000) in the simulation study and has interesting practical properties. Finally, the estimators were used to evaluate abilities of a marker combining age and a cognitive test to predict dementia in the elderly. Data were obtained from the French PAQUID cohort. The censoring appears clearly marker-dependent leading to appreciable differences between ROC curves estimated with the different methods.
[show abstract][hide abstract] ABSTRACT: Incidence of dementia increases sharply with age and, because of the increase in life expectancy, the number of dementia cases is expected to rise dramatically over time. Some studies suggest that controlling some modifiable risk factors for dementia like diabetes or hypertension could lower its incidence. However, as treating these vascular factors would also reduce mortality risk, the actual impact of such public-health intervention on dementia prevalence is not known. Accounting for the impact of dementia and risk factors on mortality, the aim of this work was (1) to compute projections of age- and-sex specific prevalence of dementia in France from 2010 to 2030, (2) to evaluate how public-health interventions targeting risk factors for dementia could change these projections. Age-and-sex specific incidence of dementia and mortality of demented subjects were estimated from the Paquid population-based cohort using a semi-parametric illness-death model. Future global mortality rates and population sizes were obtained from national demographic projections. Under the assumption that life expectancy will increase by 3.5 years for men and 2.8 years for women by 2030, the number of subjects with dementia was estimated to increase by about 75 % from 2010 to 2030 with a 200 % increase after 90 years of age. Therapeutic intervention on the whole population reducing high blood pressure prevalence would lead to a decrease in both dementia incidence rates and mortality and would have a modest impact on the number of dementia cases. On the other hand, a preventive dementia treatment targeting ApoE4 carriers would probably not improve survival and hence would decrease dementia prevalence by 15-25 %.
European Journal of Epidemiology 06/2013; · 5.12 Impact Factor
[show abstract][hide abstract] ABSTRACT: Purpose: To describe dry eye disease in French elderly subjects. Methods: The Alienor Study is a population-based study on age-related eye disease in 963 residents of Bordeaux (France), aged 73 years or more. Self-reported dry eye disease and use of artificial tears were documented through face-to-face interview. Dry eye symptoms were assessed using the Ocular Surface Disease Index (OSDI) questionnaire and tear film stability by tear break-up time measurements (TBUT). Definite dry eye disease was defined as self-reported dry eye, confirmed by use of artificial tears and/or OSDI greater or equal to 22. Results: Nine hundred and fifteen subjects, with mean age of 80 ± 4 years, returned the OSDI questionnaire. Of these, 271 (29.6%) subjects reported a dry eye disease and 135 (14.7%) were using artificial tears. An OSDI score > 22 was found in 359 (39.2%) subjects and a TBUT < 5 seconds in 335/746 (44.9%) subjects. Overall, definite dry eye affected 21.9% of subjects and was more frequent in women (27.1%) than in men (13.6%). After multivariate adjustment, dry eye disease was also significantly less frequent in subjects with high educational level (odds ratio (OR) = 0.49, 95% confidence interval (CI): 0.31-0.78 for long secondary school) and more frequent in subjects with ocular hypertension (OR = 1.61, 95% CI: 1.02-2.57) and those using anxiolytics (OR = 1.53, 95% CI: 1.02-2.29). Conclusions: This large observational study confirmed the high prevalence of dry eye symptoms among elderly subjects and confirmed some of the previously identified risk factors (in particular female gender and use of anxiolytics).