The health status: the ignored risk factor in dementia incidence. NEDICES cohort.

BACKGROUND: The causes of the dementia decrease in affluent countries are not well known but health amelioration could probably play a major role. Nevertheless, although many vascular and systemic disorders in adult life are well-known risk factors (RF) for dementia and Alzheimer disease (AD), health status is rarely considered as a single RF. AIM: To analyse whether the health status and the self-perceived health (SPH) could be RF for dementia and AD and to discuss its biological basis. METHODS: We analysed different objective health measures and SPH as RF for dementia and AD incidence in 4569 participants of the NEDICES cohort by means of Cox-regression models. The mean follow-up period was 3.2 (range: 0.03-6.6) years. RESULTS: Ageing, low education, history of stroke, and "poor" SPH were the main RF for dementia and AD incidence, whereas physical activity was protective. "Poor" SPH had a hazard ratio = 1.66 (95% CI 1.17-2.46; p = 0.012) after controlling for different confounders. DISCUSSION: According to data from NEDICES cohort, SPH is a better predictor of dementia and AD than other more objective health status proxies. SPH should be considered a holistic and biologically rooted indicator of health status, which can predict future development of dementia and AD in older adults. CONCLUSIONS: Our data indicate that it is worthwhile to include the SPH status as a RF in the studies of dementia and AD incidence and to explore the effect of its improvement in the evolution of this incidence.

Predementia constructs: Mild cognitive impairment or mild neurocognitive disorder? A narrative review.

BACKGROUND: Predementia is a heuristic umbrella concept to classify older adults with cognitive impairment who do not suffer dementia. Many diagnostic entities have been proposed to address this concept, but most of them have not had widespread acceptance. AIMS: To review clinical definitions, epidemiologic data (prevalence, incidence) and rate of conversion to dementia of the main predementia constructs, with special interest in the two most frequently used: mild cognitive impairment (MCI) and minor neurocognitive disorder (miNCD). METHODS: We have selected in three databases (MEDLINE, Web of Science and Google scholar) the references from inception to 31 December 2019 of relevant reviews, population and community-based surveys, and clinical series with >500 participants and >3 years follow-up as the best source of evidence. MAIN RESULTS: The history of predementia constructs shows that MCI is the most referred entity. It is widely recognized as a clinical syndrome harbinger of dementia of several etiologies, mainly MCI due to Alzheimer's disease. The operational definition of MCI has shortcomings: vagueness of its requirement of "preserved independence in functional abilities" and others. The recent miNCD construct presents analogous difficulties. Current data indicate that it is a stricter predementia condition, with lower prevalence than MCI, less sensitivity to cognitive decline and, possibly, higher conversion rate to dementia. CONCLUSIONS: MCI is a widely employed research and clinical entity. Preliminary data indicate that the clinical use of miNCD instead of MCI requires more scientific evidence. Both approaches have common limitations that need to be addressed.

A protective personal factor against disability and dependence in the elderly: an ordinal regression analysis with nine geographically-defined samples from Spain.

BACKGROUND: Sense of Coherence (SOC) is defined as a tendency to perceive life experiences as comprehensible, manageable and meaningful. The construct is split in three major domains: Comprehensibility, Manageability, and Meaningfulness. SOC has been associated with successful coping strategies in the face of illness and traumatic events and is a predictor of self-reported and objective health in a variety of contexts. In the present study we aim to evaluate the association of SOC with disability and dependence in Spanish elders. METHODS: A total of 377 participants aged 75 years or over from nine locations across Spain participated in the study (Mean age: 80.9 years; 65.3% women). SOC levels were considered independent variables in two ordinal logistic models on disability and dependence, respectively. Disability was established with the World health Organization-Disability Assessment Schedule 2.0 (36-item version), while dependence was measured with the Extended Katz Index on personal and instrumental activities of daily living. The models included personal (sex, age, social contacts, availability of an intimate confidant), environmental (municipality size, access to social resources) and health-related covariates (morbidity). RESULTS: High Meaningfulness was a strong protective factor against both disability (Odds Ratio [OR] = 0.50; 95% Confidence Interval [CI] = 0.29-0.87) and dependence (OR = 0.33; 95% CI = 0.19-0.58) while moderate and high Comprehensibility was protective for disability (OR = 0.40; 95% CI = 0.22-0.70 and OR = 0.39; 95%CI = 0.21-0.74), but not for dependence. Easy access to social and health resources was also highly protective against both disability and dependence. CONCLUSIONS: Our results are consistent with the view that high levels of SOC are protective against disability and dependence in the elderly. Elderly individuals with limited access to social and health resources and with low SOC may be a group at risk for dependence and disability in Spain.

Memory impairment in a simple recall task increases mortality at 10 years in non-demented elderly.

OBJECTIVE: To evaluate whether memory impairment detected in the three-word delayed recall task of the Mini-Mental State Examination (MMSE) increases the risk of mortality. METHODS: The NEDICES (Neurological Diseases in Central Spain) cohort study, is a population census-based study, aimed at detecting age-associated neurological diseases in people aged 65 and over, living in one rural and two urban communities in central Spain. Participants with dementia or without MMSE evaluation at baseline were excluded. Mortality was evaluated 10.67 years after enrollment. Cox's proportional hazards regression models were used to evaluate the hazard of death according to performance in the three-word delayed recall task included in the MMSE (score 0-3), adjusting for potential covariates (sex, age, level of education, and comorbidity). Survival was estimated using Kaplan-Meier method. RESULTS: The final study population comprised 3778 non-demented elderly subjects. After adjusting for confounding covariates, mortality was 52% greater in persons with the lowest memory score (0) vs. persons with the highest score (3). Hazard ratios (HR) showed a tendency to an increase in mortality from the highest to the lowest memory score, which was statistically significant for the groups with none (HR=1.52; CI=1.27-1.80) or one (HR=1.24; CI=1.04-1.48) word recall. Older age, male sex, and comorbidity were also associated with mortality, but level of education was not. CONCLUSIONS: Memory impairment in the three-word delayed free recall, a very simple task used by physicians worldwide, increases the risk of mortality at 10 years in non-demented elderly.

Low morale is associated with increased risk of mortality in the elderly: a population-based prospective study (NEDICES).

OBJECTIVE: the study aimed to assess the association between morale and mortality. DESIGN: we used data from the Neurological Disorders in Central Spain (NEDICES), a population-based study. SUBJECTS: 2,516 older persons (mean age 75.7 years) participated in the study. METHODS: Cox models were used to estimate risk of mortality. Morale was assessed using the Philadelphia Geriatric Center Morale Scale. RESULTS: 489 (21.8%) participants died over a median follow-up of 5.9 years (range 0.1-7.7 years), including 253 (21.8%) deaths among 1,163 participants with low morale scores, 168 (19.3%) among 870 participants with moderate scores and 68 (14.1%) among participants with high scores. In an unadjusted Cox model, relative risk (RR) of mortality in participants with low morale scores = 1.69 (P < 0.001) and RR in participants with moderate scores = 1.47 (P < 0.01) were compared to the reference group (participants with high scores). In a Cox model that adjusted for a variety of demographic factors and co-morbidities, RR of mortality in participants with low morale scores = 1.35 (P <0.05) and moderate scores = 1.16 (not significant) were compared to the reference group. CONCLUSION: low morale may be an independent predictor of mortality in the elderly. By assessing morale, practitioners might be better positioned to identify patients with poorer prognoses.

Prevalence of dementia and major dementia subtypes in Spanish populations: a reanalysis of dementia prevalence surveys, 1990-2008.

BACKGROUND: This study describes the prevalence of dementia and major dementia subtypes in Spanish elderly. METHODS: We identified screening surveys, both published and unpublished, in Spanish populations, which fulfilled specific quality criteria and targeted prevalence of dementia in populations aged 70 years and above. Surveys covering 13 geographically different populations were selected (prevalence period: 1990-2008). Authors of original surveys provided methodological details of their studies through a systematic questionnaire and also raw age-specific data. Prevalence data were compared using direct adjustment and logistic regression. RESULTS: The reanalyzed study population (aged 70 year and above) was composed of Central and North-Eastern Spanish sub-populations obtained from 9 surveys and totaled 12,232 persons and 1,194 cases of dementia (707 of Alzheimer's disease, 238 of vascular dementia). Results showed high variation in age- and sex-specific prevalence across studies. The reanalyzed prevalence of dementia was significantly higher in women; increased with age, particularly for Alzheimer's disease; and displayed a significant geographical variation among men. Prevalence was lowest in surveys reporting participation below 85%, studies referred to urban-mixed populations and populations diagnosed by psychiatrists. CONCLUSION: Prevalence of dementia and Alzheimer's disease in Central and North-Eastern Spain is higher in females, increases with age, and displays considerable geographic variation that may be method-related. People suffering from dementia and Alzheimer's disease in Spain may approach 600,000 and 400,000 respectively. However, existing studies may not be completely appropriate to infer prevalence of dementia and its subtypes in Spain until surveys in Southern Spain are conducted.

Ten-year fatal and non-fatal myocardial infarction incidence in elderly populations in Spain: the EPICARDIAN cohort study.

BACKGROUND: In Spain, more than 85% of coronary heart disease deaths occur in adults older than 65 years. However, coronary heart disease incidence and mortality in the Spanish elderly have been poorly described. The aim of this study is to estimate the ten-year incidence and mortality rates of myocardial infarction in a population-based large cohort of Spanish elders. METHODS: A population-based cohort of 3729 people older than 64 years old, free of previous myocardial infarction, was established in 1995 in three geographical areas of Spain. Any case of fatal and non-fatal myocardial infarction was investigated until December 2004 using the "cold pursuit method", previously used and validated by the the WHO-MONICA project. RESULTS: Men showed a significantly (p < 0.001) higher cumulative incidence of myocardial infarction (7.2%; 95%CI: 5.94-8.54) than women (3.8%; 95%CI: 3.06-4.74). Although cumulative incidence increased with age (p < 0.05), gender-differences tended to narrow. Adjusted incidence rates were higher in men (957 per 100 000 person-years) than in women (546 per 100 000 person-years) (p < 0.001) and increased with age (p < 0.001). The increase was progressive in women but not in men. Adjusted mortality rates were also higher in men than in women (p < 0.001), being three times higher in the age group of > or = 85 years old than in the age group of 65-74 years old (p < 0.001). CONCLUSION: Incidence of fatal and non-fatal myocardial infarction is high in the Spanish elderly population. Men show higher rates than women, but gender differences diminish with age.

Non-steroidal anti-inflammatory drugs use in older adults decreases risk of Alzheimer's disease mortality.

Alzheimer disease (AD) mortality risk in a large cohort of subjects treated or not with non-steroidal anti-inflammatory drugs (NSAIDs) is unknown. Our objective was to determine whether NSAIDs use is associated with decreased risk of AD mortality. In this prospective, population-based study (Neurological Disorders in Central Spain [NEDICES]) of 5,072 people without AD (aged 65 years and older), sociodemographic, comorbidity factors, and current medications were recorded at baseline. Community-dwelling older adults were followed for a median of 12.7 years, after which the death certificates of deceased participants were examined. 2,672 (52.7%) of 5,072 participants died, including 504 (18.9%) NSAIDs users and 2,168 (81.1%) non-users. Of the 2,672 deceased participants, 113 (4.2%) had AD as a cause of death (8 [1.6%] among NSAIDs users and 105 [4.8%] among non-users, chi-square = 10.70, p = 0.001). In an unadjusted Cox model, risk of AD mortality was decreased in NSAIDs users (hazard ratio [HR] for AD mortality = 0.35, 95% confidence interval [CI] 0.17-0.72, p = 0.004) when compared to non-users. After adjusting for numerous demographic factors and co-morbidities, the HR for AD mortality in NSAIDs users was 0.29, 95% CI 0.12-0.73, p = 0.009. Stratified analyses showed a significantly decreased risk of AD mortality with aspirin, whereas non-aspirin NSAIDs only showed a statistical trend toward significance in the adjusted Cox regression models. NSAIDs use was associated with 71% decreased risk of AD mortality in older adults. Our results support the hypothesis that NSAIDs use is a protective factor of developing AD.

Disability subtypes and mortality rates in older adults: A longitudinal population-based study (NEDICES).

OBJECTIVE: We investigated the mortality rates of three subtypes of disability and their specific explanatory factors in older adults. METHODS: Our data come from NEDICES, a population-based longitudinal cohort study of Spanish older adults. We examined 3816 participants without dementia who completed the Pfeffer's Functional Activities Questionnaire (FAQ) and an assessment of self-perceived functional limitations (SFL) associated with health conditions. Subjects were classified into mutually exclusive subtypes of disability: subtype 1 (SFL), subtype 2 (impaired FAQ), and subtype 3 (impaired FAQ plus SFL). Factors related to all disability subtypes were analyzed using a multinomial logistic regression (MLR), whereas Cox regression (CR) models adjusted by covariates were applied to compare survival rates between groups at the 5-year follow up. RESULTS: The CR models indicated that SFL and FAQ scores were associated with higher risk of mortality at 5-years. After stratifying by subtypes of disability, mortality was significantly higher in subtype 3 than in subtypes 1 and 2. All models were consistent after adjusting by different covariates. The MLR showed that subtype 1 was specifically associated with the number of comorbidities, whereas subtype 2 was associated with lower MMSE scores depression and living in nursing homes. CONCLUSIONS: Our results show that the combination of impaired FAQ plus SFL have an increased differential predictive utility for mortality than approaches based on unique measures. They also indicate that both measures of disability are associated with different explanatory factors.

Neurological Disorders in Central Spain, Second Survey: Feasibility Pilot Observational Study.

BACKGROUND: The Neurological Disorders in Central Spain, second survey (NEDICES-2) is a population-based, closed-cohort study that will include over 8000 subjects aged ≥55 years. It will also include a biobank. OBJECTIVE: The objective of this study was to evaluate all major aspects of the NEDICES-2 (methods, database, screening instruments, and questionnaires, as well as interexpert rating of the neurological diagnoses) in each one of the planned areas (all of them in central Spain) and to test the possibility of obtaining biological samples from each participant. METHODS: A selection of patients and participants of the planned NEDICES-2 underwent face-to-face interviews including a comprehensive questionnaire on demographics, current medications, medical conditions, and lifestyle habits. Biological samples (blood, saliva, urine, and hair) were also obtained. Furthermore, every participant was examined by a neurologist. RESULTS: In this pilot study, 567 study participants were enrolled (196 from hospitals and 371 from primary care physician lists). Of these 567, 310 completed all study procedures (questionnaires and the neurological evaluation). The study was time-consuming for several primary care physicians. Hence, a few primary care physicians from some areas refused to participate, which led to a reconfiguration of study areas. In addition, the central biobank needed to be supplemented by the biobanks of local Spanish National Health System hospitals. CONCLUSIONS: Population-based epidemiological surveys, such as the NEDICES-2, require a pilot study to evaluate the feasibility of all aspects of a future field study (population selection, methods and instruments to be used, neurological diagnosis agreement, and data collection).

Diabetes and Prediabetes Classification Using Glycemic Variability Indices From Continuous Glucose Monitoring Data.

BACKGROUND: Tens of glycemic variability (GV) indices are available in the literature to characterize the dynamic properties of glucose concentration profiles from continuous glucose monitoring (CGM) sensors. However, how to exploit the plethora of GV indices for classifying subjects is still controversial. For instance, the basic problem of using GV indices to automatically determine if the subject is healthy rather than affected by impaired glucose tolerance (IGT) or type 2 diabetes (T2D), is still unaddressed. Here, we analyzed the feasibility of using CGM-based GV indices to distinguish healthy from IGT&T2D and IGT from T2D subjects by means of a machine-learning approach. METHODS: The data set consists of 102 subjects belonging to three different classes: 34 healthy, 39 IGT, and 29 T2D subjects. Each subject was monitored for a few days by a CGM sensor that produced a glucose profile from which we extracted 25 GV indices. We used a two-step binary logistic regression model to classify subjects. The first step distinguishes healthy subjects from IGT&T2D, the second step classifies subjects into either IGT or T2D. RESULTS: Healthy subjects are distinguished from subjects with diabetes (IGT&T2D) with 91.4% accuracy. Subjects are further subdivided into IGT or T2D classes with 79.5% accuracy. Globally, the classification into the three classes shows 86.6% accuracy. CONCLUSIONS: Even with a basic classification strategy, CGM-based GV indices show good accuracy in classifying healthy and subjects with diabetes. The classification into IGT or T2D seems, not surprisingly, more critical, but results encourage further investigation of the present research.

[Epidemiology of lipid profile of the Spanish elderly population: the EPICARDIAN study]. / Epidemiología del perfil lipídico de la población anciana española: el estudio EPICARDIAN.

BACKGROUND AND OBJECTIVE: The aim of this study was to describe the lipid profile, the levels of serum total cholesterol (TC), LDL cholesterol (C-LDL), HDL cholesterol (C-HDL) and triglyceride (TG), to compare these levels between geographical areas and to estimate the prevalence of dyslipidemia in elderly residents (65 years and older) from urban and rural areas of Spain. PATIENTS AND METHOD: Epidemiological, observational, multicentre study of Spanish elderly people residents (>or= 65 years old) of 3 communities in 3 Spanish regions: Arévalo (Avila) and Begonte (Lugo) as rural areas and Lista (Central Madrid) as urban area. Stratified randomized sample by age and sex from population census of each area. The participation rate was: 84.6%. At-home interviews (phase 1) (n = 4522): with determination of capillary blood cholesterol levels (Reflotron) and clinical visit (phase 2) (1/3 selected randomly, n = 1907): determination of serum TC levels (enzymatic colorimetric method CHOP-PAD), C-HDL, C-LDL (Friedewald equation) and TG (Trinder Method). RESULTS: Mean concentrations of TC was 230.3 (46.8) mg/dl. These levels decreased significantly with increasing age (p < 0.001), higher in women (p = 0.001); lower in Lugo (226.4 [49.7] mg/dl) than in Madrid (233.2 [42.3] mg/dl) and Arévalo (236.5 [43] mg/dl) (p = 0.002). Global prevalence of hypercholesterolemia by SEA simplified criteria was: 68.9% (95% confidence interval, 66.8-71). Mean concentrations of C-LDL was: 159.4 (37.9) mg/dl; C-HDL: 48.2 (15) mg/dl, and TG: 119.7 (63.85) mg/dl. 31% of cases were awarded about the hypercholesterolemia. Only 30% of them were under treatment with lipid lowering drugs; and 30% of the subjects showed CT concentrations < 200 mg/dl, with no differences by sex, age, study area or education level. Female sex, urban habitat and hypertension were the only variables independently associated to hypercholesterolemia in the logistic model. CONCLUSIONS: The prevalence of dyslipidemia is slightly higher to SEA estimation for the European elderly population (50%), greater in women and in younger groups. The awareness, treatment and control of hypercholesterolemia are low among the Spanish elderly population.

Blood harmane (1-methyl-9H-pyrido[3,4-b]indole) concentration in essential tremor cases in Spain.

BACKGROUND: Environmental correlates for essential tremor (ET) are largely unexplored. The search for such environmental factors has involved the study of a number of neurotoxins. Harmane (1-methyl-9H-pyrido[3,4-b]indole) is a potent tremor-producing toxin. In two prior case-control studies in New York, we demonstrated that blood harmane concentration was elevated in ET patients vs. controls, and especially in familial ET cases. These findings, however, have been derived from a study of cases ascertained through a single tertiary referral center in New York. OBJECTIVE: Our objective was to determine whether blood harmane concentrations are elevated in familial and sporadic ET cases, ascertained from central Spain, compared to controls without ET. METHODS: Blood harmane concentrations were quantified by a well-established high performance liquid chromatography method. RESULTS: The median harmane concentrations were: 2.09 g(-10)/ml (138 controls), 2.41 g(-10)/ml (68 sporadic ET), and 2.90 g(-10)/ml (62 familial ET). In an unadjusted logistic regression analysis, log blood harmane concentration was not significantly associated with diagnosis (familial ET vs. control): odds ratio=1.56, p=0.26. In a logistic regression analysis that adjusted for evaluation start time, which was an important confounding variable, the odds ratio increased to 2.35, p=0.049. CONCLUSIONS: Blood harmane levels were slightly elevated in a group of familial ET cases compared to a group of controls in Spain. These data seem to further extend our observations from New York to a second cohort of ET cases in Spain. This neurotoxin continues to be a source of interest for future confirmatory research.

A population-based study of cognitive function in older people with subjective memory complaints.

Given the uncertain relationship between objective and subjective memory complaints (SMC), we conducted a study of cognitive function in older people with memory complaints in a large population-based elderly Spanish cohort (NEDICES). A total of 1,073 subjects with SMC and 1,073 matched controls free from dementia underwent a neuropsychological assessment, including tests of global cognitive performance, frontal executive function, verbal fluency, and memory. SMC were associated with a number of specific objective cognitive deficits including poor verbal fluency, and poor immediate and delayed recall. However, there was a limited association with global cognitive impairment despite a strong influence upon Pfeffer Functional Activities Questionnaire based daily function. In the full sample the strongest predictors of SMC were poor psychological well-being, depressive symptoms (including those taking antidepressants) and hearing impairment. Moderate predictors were age and gender. If individuals with mild cognitive impairment (MCI) were removed, then the strongest predictors were poor psychological well-being, depressive symptoms, hearing impairment, illiteracy, age, and gender. For those with MCI alone, the only significant predictor of memory complaints was poor psychological well-being. Predictors of SMC in those with depressive symptoms included poor psychological well-being and hearing impairment. With depressive symptoms excluded the strongest predictors were poor psychological well-being, hearing impairment, illiteracy, and gender. In this population-based sample, individuals with SMC had evidence of impairments on specific neuropsychological testing which might not be apparent on global measures. Predictors of SMC may differ in those with versus without MCI and those with versus without depressive symptoms.

Statins and cognitive functioning in the elderly: a population-based study.

In a 2009 Cochrane review, the authors concluded that there is good evidence that statins, given in late life to people at risk of vascular disease, have no effect in preventing Alzheimer's disease or dementia. A related issue, which remains unclear, is whether statins improve cognitive function. While some studies have shown a beneficial effect of statins on cognitive function, others have observed mild detrimental effects on cognition. Our aim was to assess cognitive function in community-dwelling elderly participants treated with statins compared with their untreated counterparts (i.e., controls) living in the same population. 137 population-dwelling participants who were receiving statins and 411 matched controls age 65 years (median=72 years) in central Spain (the Neurological Disorders in Central Spain [NEDICES] study) underwent a neuropsychological assessment, including tests of global cognitive performance, frontal-executive function, verbal fluency, and memory. Median duration of statin treatment was 2 years. Of 137 participants receiving statins, 53 (38.7%) were taking pravastatin, 38 (27.7%) simvastatin, 37 (27.0%) lovastatin, 6 (4.4%) fluvastatin, and 3 (2.2%) atorvastatin. Although initial univariate analyses indicated some differences, after adjusting for age, gender, education, depressive symptoms, premorbid intelligence, medications that potentially affect cognitive function, and blood cholesterol levels, statin users and controls performed similarly on all neuropsychological tests. In this population-based sample, elderly participants treated with statins and untreated controls performed similarly in all tested cognitive areas. These results do not support a positive benefit of statins on cognition.

Several factors influenced attrition in a population-based elderly cohort: neurological disorders in Central Spain Study.

OBJECTIVE: We studied attrition (i.e., participant dropout) 3 years after the baseline interview in a population-based Spanish cohort. STUDY DESIGN AND SETTING: The Neurological Disorders in Central Spain study is a longitudinal, population-based survey of chronic neurologic conditions in persons aged > or = 65 years. Multivariate logistic regression analysis was used to examine baseline differences between participants who took part in the 3-year follow-up evaluation vs. those who did not. RESULTS: Of the 5,278 participants evaluated at baseline (1994-1995), 1,482 (28.1%) were lost to the follow-up (1997-1998). Factors that were associated with dropout due to refusal were as follows: living in a rural area and being single. Contact failure was associated with older age and being unmarried and widowed. Unreachable participants were less likely to take three or more medications or live in a professional neighborhood. Predictors of dropout due to death were male gender, older age, having impaired activities of daily living, taking more medications, poor self-perceived health, dementia, and smoking. CONCLUSIONS: These findings on participants who are at high risk of dropout may be useful in the planning phase of future prospective studies. Of the possible reasons for attrition, refusal is the most important because it is amenable to change.

Prevalence of essential tremor in three elderly populations of central Spain.

Although essential tremor (ET) is considered the most prevalent adult movement disorder, the available information on its prevalence and distribution worldwide is not completely understood. We investigated the prevalence and distribution of ET in three elderly Spanish populations using a door-to-door, two-phase approach. A brief screening instrument was administered on May 1, 1994 to subjects over 64 years old taken from the census of one urban municipality of Greater Madrid (quarter of Margaritas, Getafe), one urban district of Madrid (Lista), and one rural site (Arévalo county, Avila) (N = 5278). Study subjects were limited to those who screened positively (N = 472). To increase reliability, each patient was examined by 3 experienced neurologists, and was classified as having ET only when all 3 neurologists agreed (183 of 472). The present study was part of a large-scale epidemiological survey of neurological diseases, and served as a baseline investigation in a 3-year incidence study. Accordingly, 41 ET patients were identified when evaluating subjects who had screened positively for dementia, stroke, or parkinsonism, despite the fact that they had screened negatively for tremor; furthermore, 32 additional ET prevalent cases were detected when evaluating subjects who had screened positively for tremor in the second cross-sectional study (May 1, 1997), although they had screened negatively for tremor in the first cross-sectional study. We identified 256 persons (152 women, 104 men) with ET; of these, 87 patients (34.0%) reported having an affected relative. Two hundred and four (79.7%) of the subjects with ET were detected through this screening and had not been diagnosed previously. The prevalence of ET was 4.8% (95% CI = 4.2-5.4) for the total population; 4.6% (95% CI = 3.7-5.4) in men and 5.0% (95% CI = 4.2-5.8) in women. Age-specific prevalence increased with advancing age for both men and women. Despite the variability in worldwide data, ET is a frequently encountered disorder in elderly people. Furthermore, as ET may be seen as a relatively benign condition, a large proportion of patients may never seek neurological attention.