Association Between Cerebral Small Vessel Disease With Antidepressant Use and Depression: 3C Dijon Magnetic Resonance Imaging Study

Background and Purpose- Evidence links antidepressant use with cerebral small vessel disease; however, it remains unclear whether people with depression face comparable risk. This study aims to determine the association between antidepressant drug use and depression with markers of cerebral small vessel disease. Methods- One thousand nine hundred five participants (mean age, 72.5 years; 60% women) without stroke or dementia history underwent brain magnetic resonance imaging at baseline, and 1402 individuals underwent a second magnetic resonance imaging at 4 years. Outcomes were lacunes 3 to 15 mm and white matter hyperintensity volume (cm³) at baseline and follow-up. Exposure to antidepressants was grouped as (1) selective serotonin reuptake inhibitors (n=68), (2) tricyclics (n=40), (3) atypicals (n=24), (4) depressed nonusers (n=303), and (5) nondepressed/nonuser group (reference group, n=1470). Statistical analyses adjusted for propensity scores due to the nonrandomized exposure to antidepressant drugs. Results- There was an association between use of atypical antidepressants with lacunes at baseline (adjusted rate ratio, 2.59 [95% CI, 1.14-5.88]; P=0.023) and follow-up (adjusted rate ratio, 3.05 [95% CI, 1.25-7.43]; P=0.014). Lacunes at baseline were also associated with depressed nonusers (adjusted rate ratio, 1.53 [95% CI, 1.06-2.21]; P=0.023). Selective serotonin reuptake inhibitor users and depressed nonusers displayed higher total, periventricular, and deep white matter hyperintensity volumes at baseline. Selective serotonin reuptake inhibitor users had higher deep white matter hyperintensity volumes at follow-up. Conclusions- Users of atypical antidepressants, selective serotonin reuptake inhibitors, and depressed people without any antidepressant exposure all displayed markers of cerebral small vessel disease higher than the nondepressed/nonuser group. The findings suggest that cerebral small vessel disease is associated with depression and exposure to antidepressants.

Neuraxial analgesia is not associated with an increased risk of post-partum relapses in MS

Background:

Obstetrical analgesia remains a matter of controversy because of the fear of neurotoxicity of local anesthetics on demyelinated fibers or their potential relationship with subsequent relapses.

Objective:

To assess the impact of neuraxial analgesia on the risk of relapse during the first 3 months post-partum, with a focus on women who experienced relapses during pregnancy.

Methods:

We analyzed data of women followed-up prospectively during their pregnancies and at least 3 months post-partum, collected in the Pregnancy in Multiple Sclerosis (PRIMS) and Prevention of Post-Partum Relapses with Progestin and Estradiol in Multiple Sclerosis (POPARTMUS) studies between 1992–1995 and 2005–2012, respectively. The association of neuraxial analgesia with the occurrence of a post-partum relapse was estimated by logistic regression analysis.

Results:

A total of 389 women were included, 215 from PRIMS and 174 from POPARTMUS. In total, 156 women (40%) had neuraxial analgesia. Overall, 24% experienced a relapse during pregnancy and 25% in the 3 months post-partum. Women with a pregnancy relapse were more likely to have a post-partum relapse (odds ratio (OR) = 1.83, p = 0.02), independently of the use of neuraxial analgesia. There was no association between neuraxial analgesia and post-partum relapse (OR = 1.08, p = 0.78).

Conclusion:

Neuraxial analgesia was not associated with an increased risk of post-partum relapses, whatever multiple sclerosis (MS) activity during pregnancy.

A Suggestion for an Effective Use of a Computer-aided Diagnosis System in Screening for Hyperthyroidism

A computer-assisted program for diagnosing hyperthyroidism, specially devoted to the screening of functional thyroid status, has been written using data provided by 359 patients, 282 euthyroid and 77 hyperthyroid. The model is based on Bayes’ theorem.

Using only 9 clinical signs and the free thyroxin index, the program achieved, on a test-sample of 117 new patients, an overall accuracy of 90% ; 10% of the cases were in the zone of uncertainty, and none was misdiagnosed.

Different screening strategies are examined and their results discussed.

The Determination of Sequential Strategies of Diagnostic Tests: Comparison of Different Methods by Simulation

Various heuristic processes for determining diagnostic test strategies were compared with the optimal sequential strategy on simulated patients. These heuristics consisted in limiting the depth and breadth of the search in the decision tree with regard to medically reasonable constraints. It appeared that some of these heuristics required a very small amount of computer time and provided solutions, the costs of which were very close to the cost of the optimal strategy.

General conclusions were drawn from an analysis of the performance of these various heuristics for varying cost functions.

Relationship Between Migraine, Blood Pressure and Carotid Thickness. A Population-Based Study in the Elderly

The relationship between migraine and blood pressure is controversial. We studied the association between migraine and blood pressure in a population-based sample of elderly patients. Participants were 1373 subjects 59-71 years of age. Lifetime migraine was diagnosed according to the International Headache Society criteria by a headache specialist. Blood pressure was measured as well as the carotid intima-media thickness (IMT) which is a good marker of the long-term exposure to high blood pressure. Migraine during life was diagnosed in 140 participants. Mean systolic blood pressure was lower in subjects with migraine than in those without headache (128 mmHg vs. 137 mmHg). There was a significant trend of decreasing frequency of migraine with increasing blood pressure and also with increasing IMT. In this study, migraine was associated with lower levels of blood pressure and with smaller values of carotid wall thickness.

Benzodiazepine, psychotropic medication, and dementia: A population-based cohort study

INTRODUCTION

Benzodiazepine use has been associated with increased risk of dementia. However, it remains unclear whether the risk relates to short or long half-life benzodiazepines and whether it extends to other psychotropic drugs.

METHODS

Prospective cohort study among 8240 individuals ≥65, interviewed on medication use. Incident dementia confirmed by an end point committee after a multistep procedure.

RESULTS

During a mean of 8 years of follow-up, 830 incident dementia cases were observed. Users of benzodiazepines at baseline had a 10% increased risk of dementia (adjusted hazard ratio [HR], 1.10; 95% confidence interval, 0.90-1.34). However, long half-life (>20 hours) benzodiazepine users had a marked increased risk of dementia (HR = 1.62; 1.11-2.37) compared with short half-life users (HR = 1.05; 0.85-1.30). Users of psychotropics had an increased risk of dementia (HR = 1.47; 1.16-1.86).

DISCUSSION

Results of this large, prospective study show increased risk of dementia for long half-life benzodiazepine and psychotropic use.

Usefulness of data from magnetic resonance imaging to improve prediction of dementia: population based cohort study

OBJECTIVE

To determine whether the addition of data derived from magnetic resonance imaging (MRI) of the brain to a model incorporating conventional risk variables improves prediction of dementia over 10 years of follow-up.

DESIGN

Population based cohort study of individuals aged ≥ 65.

SETTING

The Dijon magnetic resonance imaging study cohort from the Three-City Study, France.

PARTICIPANTS

1721 people without dementia who underwent an MRI scan at baseline and with known dementia status over 10 years' follow-up.

MAIN OUTCOME MEASURE

Incident dementia (all cause and Alzheimer's disease).

RESULTS

During 10 years of follow-up, there were 119 confirmed cases of dementia, 84 of which were Alzheimer's disease. The conventional risk model incorporated age, sex, education, cognition, physical function, lifestyle (smoking, alcohol use), health (cardiovascular disease, diabetes, systolic blood pressure), and the apolipoprotein genotype (C statistic for discrimination performance was 0.77, 95% confidence interval 0.71 to 0.82). No significant differences were observed in the discrimination performance of the conventional risk model compared with models incorporating data from MRI including white matter lesion volume (C statistic 0.77, 95% confidence interval 0.72 to 0.82; P=0.48 for difference of C statistics), brain volume (0.77, 0.72 to 0.82; P=0.60), hippocampal volume (0.79, 0.74 to 0.84; P=0.07), or all three variables combined (0.79, 0.75 to 0.84; P=0.05). Inclusion of hippocampal volume or all three MRI variables combined in the conventional model did, however, lead to significant improvement in reclassification measured by using the integrated discrimination improvement index (P=0.03 and P=0.04) and showed increased net benefit in decision curve analysis. Similar results were observed when the outcome was restricted to Alzheimer's disease.

CONCLUSIONS

Data from MRI do not significantly improve discrimination performance in prediction of all cause dementia beyond a model incorporating demographic, cognitive, health, lifestyle, physical function, and genetic data. There were, however, statistical improvements in reclassification, prognostic separation, and some evidence of clinical utility.

Primary prevention with lipid lowering drugs and long term risk of vascular events in older people: population based cohort study

OBJECTIVE

To determine the association between use of lipid lowering drugs (statin or fibrate) in older people with no known history of vascular events and long term risk of coronary heart disease and stroke

DESIGN

Ongoing prospective population based cohort study recruited in 1999-2000, with five face-to-face examinations.

SETTING

Random sample of community dwelling population aged 65 years and over, living in three French cities (Bordeaux, Dijon, Montpellier).

PARTICIPANTS

7484 men and women (63%) with mean age 73.9 years and no known history of vascular events at entry. Mean follow-up was 9.1 years.

MAIN OUTCOME MEASURES

Adjusted hazard ratios of coronary heart disease and stroke in baseline lipid lowering drug users compared with non-users, calculated using multivariable Cox proportional hazard models adjusted for numerous potential confounding factors. Hazard ratios were estimated for use of any lipid lowering drug and for statin and fibrate separately.

RESULTS

Lipid lowering drug users were at decreased risk of stroke compared with non-users (hazard ratio 0.66, 95% confidence interval 0.49 to 0.90); hazard ratios for stroke were similar for statin (0.68, 0.45 to 1.01) and fibrate (0.66, 0.44 to 0.98). No association was found between lipid lowering drug use and coronary heart disease (hazard ratio 1.12, 0.90 to 1.40). Analyses stratified by age, sex, body mass index, hypertension, systolic blood pressure, triglyceride concentrations, and propensity score did not show any effect modification by these variables, either for stroke or for coronary heart disease.

CONCLUSION

In a population based cohort of older people with no history of vascular events, use of statins or fibrates was associated with a 30% decrease in the incidence of stroke.

A genome-wide association meta-analysis of plasma Aβ peptides concentrations in the elderly

Amyloid beta (Aβ) peptides are the major components of senile plaques, one of the main pathological hallmarks of Alzheimer disease (AD). However, Aβ peptides' functions are not fully understood and seem to be highly pleiotropic. We hypothesized that plasma Aβ peptides concentrations could be a suitable endophenotype for a genome-wide association study (GWAS) designed to (i) identify novel genetic factors involved in amyloid precursor protein metabolism and (ii) highlight relevant Aβ-related physiological and pathophysiological processes. Hence, we performed a genome-wide association meta-analysis of four studies totaling 3 528 healthy individuals of European descent and for whom plasma Aβ1-40 and Aβ1-42 peptides levels had been quantified. Although we did not observe any genome-wide significant locus, we identified 18 suggestive loci (P<1 × 10(-)(5)). Enrichment-pathway analyses revealed canonical pathways mainly involved in neuronal functions, for example, axonal guidance signaling. We also assessed the biological impact of the gene most strongly associated with plasma Aβ1-42 levels (cortexin 3, CTXN3) on APP metabolism in vitro and found that the gene protein was able to modulate Aβ1-42 secretion. In conclusion, our study results suggest that plasma Aβ peptides levels are valid endophenotypes in GWASs and can be used to characterize the metabolism and functions of APP and its metabolites.

Plasma lipids and cerebral small vessel disease

OBJECTIVES

We examined the cross-sectional association between lipid fractions and 2 MRI markers of cerebral small vessel disease, white matter hyperintensity volume (WMHV) and lacunes, representing powerful predictors of stroke and dementia.

METHODS

The study sample comprised 2,608 participants from the 3C-Dijon Study (n = 1,842) and the Epidemiology of Vascular Aging Study (EVA) (n = 766), 2 large French population-based cohorts (72.8 ± 4.1 and 68.9 ± 3.0 years; 60.1% and 58.4% women, respectively). Analyses were performed separately in each study and combined using inverse variance meta-analysis. Lipid fractions (triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol) were studied as continuous variables. WMHV was studied both in a continuous and dichotomous manner, the latter reflecting the age-specific top quartile of WMHV (EXT-WMHV). Analyses were adjusted for age and sex.

RESULTS

Increasing triglycerides were associated with larger WMHV in the 3C-Dijon Study (β ± SE = 0.0882 ± 0.0302, p = 0.0035), in the EVA Study (β ± SE = 0.1062 ± 0.0461, p = 0.021), and in the combined analysis (β ± SE = 0.0936 ± 0.0252, p = 0.0002) and with higher frequency of lacunes in the 3C-Dijon Study (odds ratio [OR] = 1.65 [95% confidence interval 1.10-2.48], p = 0.015), in the EVA Study (OR = 1.58 [95% confidence interval 0.93-2.70], p = 0.09), and in the combined analysis (OR = 1.63 [95% confidence interval 1.18-2.25], p = 0.003). Associations were attenuated but maintained after adjusting for other vascular risk factors or for inflammatory markers. Associations were present and in the same direction both in participants taking and those not taking lipid-lowering drugs but tended to be stronger in the former for EXT-WMHV. Increasing low-density lipoprotein cholesterol tended to be associated with a decreased frequency and severity of all MRI markers of cerebral small vessel disease in both studies.

CONCLUSIONS

Increasing triglycerides but not other lipid fractions were associated with MRI markers of cerebral small vessel disease in older community persons.

Older age at retirement is associated with decreased risk of dementia

To test the hypothesis that age at retirement is associated with dementia risk among self-employed workers in France, we linked health and pension databases of self-employed workers and we extracted data of those who were still alive and retired as of December 31st 2010. Dementia cases were detected in the database either through the declaration of a long-term chronic disease coded as Alzheimer's disease and other dementia (International Classification of Disease codes G30, F00, F01, F03) or through the claim for reimbursement of one of the anti-dementia drugs. Data were analyzed using Cox proportional hazard model adjusting for potential confounders. Among the 429,803 retired self-employed workers alive on December 31st 2010, prevalence of dementia was 2.65 %. Multivariable analyses showed that the hazard ratio of dementia was 0.968 [95 % confidence interval = (0.962-0.973)] per each extra year of age at retirement. After excluding workers who had dementia diagnosed within the 5 years following retirement, the results remained unchanged and highly significant (p < 0.0001). We show strong evidence of a significant decrease in the risk of developing dementia associated with older age at retirement, in line with the "use it or lose it" hypothesis. Further evidence is necessary to evaluate whether this association is causal, but our results indicate the potential importance of maintaining high levels of cognitive and social stimulation throughout work and retiree life.

Impact of allopurinol on risk of myocardial infarction

BACKGROUND

Gout therapy includes xanthine oxidase inhibitors (XOI) and colchicine, which have both been associated with decreased cardiovascular risk. However, their effects on major cardiac events, such as myocardial infarction (MI), need to be investigated further.

OBJECTIVES

To investigate whether XOIs and colchicine are associated with decreased risk of MI.

METHODS

This case-control study compared patients with first-ever MI and matched controls. Cases were recruited from the Pharmacoepidemiological General Research on MI registry. Controls were selected from a referent population (n=8444) from general practice settings.

RESULTS

The study sample consisted of 2277 MI patients and 4849 matched controls. Use of allopurinol was reported by 3.1% of cases and 3.8 of controls, and 1.1% of cases and controls used colchicine. The adjusted OR (95% CI) for MI with allopurinol use was 0.80 (0.59 to 1.09). When using less stringent matching criteria that allowed for inclusion of 2593 cases and 5185 controls, the adjusted OR was 0.73 (0.54 to 0.99). Similar results were found on analysis by sex and hypertension status. Colchicine used was not associated with a decreased risk of MI (aOR=1.17 (0.70 to 1.93)).

CONCLUSIONS

Allopurinol may be associated with a reduced risk of MI. No decreased risk of MI was found in colchicine users. Besides its urate-lowering property, allopurinol might have a cardioprotective effect.

Risk of breast cancer by individual insulin use: an international multicenter study

OBJECTIVE Several studies have been published in 2009 suggesting a possible association between insulin glargine and increased risk of malignancies, including breast cancer. The objective of this study was to assess the relation between the individual insulins (glargine, aspart, lispro, and human insulin) and development of breast cancer. RESEARCH DESIGN AND METHODS Seven hundred seventy-five incident cases of primary invasive or in situ carcinoma breast cancer occurring in women with diabetes from 92 centers in the U.K., Canada, and France were matched to a mean of 3.9 diabetic community control subjects (n = 3,050; recruited from 580 general practices) by country, age, recruitment date, and diabetes type and management. The main risk model was a multivariate conditional logistic regression model with case/control status as the dependent variable and individual insulin use, 8 years preceding the index date, as the independent variable, controlling for past use of any insulin, oral antidiabetes drugs, reproductive factors, lifestyle, education, hormone replacement therapy and history of contraceptive use, BMI, comorbidities, diabetes duration, and annual number of physician visits. Glargine was also compared with every other insulin by computing all ratios using the variance-covariance matrix of logistic model parameters. RESULTS Adjusted odds ratios of breast cancer for each type of insulin versus no use of that insulin were 1.04 (95% CI 0.76-1.44) for glargine, 1.23 (0.79-1.92) for lispro, 0.95 (0.64-1.40) for aspart, and 0.81 (0.55-1.20) for human insulin. Two-by-two comparisons found no difference between glargine and the different types of insulins. Insulin dosage or duration of use and tumor stage did not change the results. CONCLUSIONS This international study found no difference in the risk of developing breast cancer in patients with diabetes among the different types of insulin with short- to mid-term duration of use. Longer-term studies would be of interest.

Gender differences in the association between socioeconomic status and subclinical atherosclerosis

OBJECTIVES

This study explored the pattern of associations between socioeconomic status (SES) and atherosclerosis progression (as indicated by carotid intima media thickness, CIMT) across gender.

DESIGN

Cross-sectional analysis of a sample of 5474 older persons (mean age 73 years) recruited between 1999 and 2001 in the 3C study (France). We fitted linear regression models including neighborhood SES, individual SES and cardiovascular risk factors.

RESULTS

CIMT was on average 24 µm higher in men (95% CI: 17 to 31). Neighborhood SES was inversely associated with CIMT in women only (highest versus lowest tertiles: -12.2 µm, 95%CI -22 to -2.4). This association persisted when individual SES and risk factors were accounted for. High individual education was associated with lower CIMT in men (-21.4 µm 95%CI -37.5 to -5.3) whereas high professional status was linked to lower CIMT among women (-15.7 µm 95%CI: -29.2 to -2.2). Adjustment for cardiovascular risk factors resulted in a slightly more pronounced reduction of the individual SES-CIMT association observed in men than in women.

CONCLUSION

In this sample, neighborhood and individual SES displayed different patterns of associations with subclinical atherosclerosis across gender. This suggests that the causal pathways leading to SES variations in atherosclerosis may differ among men and women.

Blood pressure variability and risk of dementia in an elderly cohort, the Three-City Study

BACKGROUND

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.

METHODS

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).

RESULTS

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.

CONCLUSIONS

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.

From genetics to dietetics: the contribution of epidemiology to understanding Alzheimer's disease

Late-life dementia results from non-modifiable risk factors such as age and genetics, modulated by deleterious and protective environmental factors among which nutrition may play a major role. This paper highlights five major recent contributions of the French Three-City (3C) and PAQUID epidemiological studies to Alzheimer's disease (AD) knowledge, targeting genetic and dietary risk factors, and the impact of cognitive decline in daily living. The 3C study contributed to a large genome-wide association study to identify new genetic risk factors for AD. In addition to apolipoprotein E (APOE), two loci gave replicated evidence of association: one within CLU, encoding clusterin or apolipoprotein J, and the other within CR1, encoding the complement component receptor 1. Although the attributable fraction of risk for these polymorphisms is moderate, genetic studies provide significant insights into the molecular bases of AD. Regarding dietary data, findings from 3C suggest that healthy diets associating sources of both omega 3 fatty acids (fish) and antioxidants (fruits and vegetables) such as the Mediterranean diet, and caffeine could be associated with decreased risk for AD. However, the protective effect of omega3 fatty acids might be limited to APOE4 non-carriers. Future research should focus on gene-nutrient interactions. Regarding the functional impact of prodromal AD, the PAQUID study showed that taking into account mild functional limitations considerably increases the predictive value of neuropsychological tests for conversion to dementia. Research should focus on sensitive instruments to capture early functional decline to improve the identification of elderly patients at high risk of conversion to dementia.

[Historical cohorts: contribution to epidemiological knowledge]

Several large cohort studies have been performed in France since the 1960s. Participants were recruited from general or occupational populations. Whatever their primary objective, these cohort studies provided important data on the prevalence and risk factors of major public health problems. The scientific value of these studies, which gave rise to a very large numbers of publications, is internationally recognized.

Abdominal obesity and late-onset asthma: cross-sectional and longitudinal results: the 3C study

Whereas global obesity assessed by BMI has been related to asthma risk, little is known as to the potential implication of abdominal adiposity in this relationship. In the elderly, in whom asthma remains poorly studied, abdominal adiposity tends to increase at the expense of muscle mass. The purpose of this study was to investigate the association between abdominal adiposity, assessed by waist circumference (WC), and prevalence and incidence of asthma in a large elderly cohort. Cross-sectional analysis was based on 7,643 participants aged ≥65 years including 592 (7.7%) with lifetime physician-diagnosed asthma. Longitudinal analysis involved 6,267 baseline nonasthmatics followed-up for a period of 4 years, 67 of whom exhibited incident asthma. Baseline WC was categorized according to sex-specific criteria (men/women): <94/80 cm (reference), [94-102[/[80-88[ (abdominal overweight), and ≥102/88 (abdominal obesity). Logistic and Cox regression models estimated asthma risk associated with WC after adjustment for age, sex, educational level, smoking status, BMI, physical ability, dyspnea, chronic bronchitis symptoms and history of cardiovascular disease. At baseline, asthma risk increased with increasing WC independently of BMI and other confounders (adjusted odds ratio (ORa), 95% confidence interval (CI): 1.30, 1.02-1.65 and ORa: 1.76, 1.31-2.36 for abdominal overweight and obesity, respectively). Asthma incidence was related to WC (hazard ratio (HRa), 95% CI: 2.69, 1.21-5.98 and HRa: 3.84, 1.55-9.49, for abdominal overweight and obesity, respectively). Estimates were similar in both sexes. In the elderly, abdominal adiposity was independently associated with increased prevalence and incidence of asthma. Studies aiming to understand the mechanisms involved in the adiposity-asthma link are needed.

Can mortality data provide reliable indicators for Creutzfeldt-Jakob disease surveillance? A study in France from 2000 to 2008

BACKGROUND

Surveillance of Creutzfeldt-Jakob disease (CJD) is still an important issue because of the variant CJD epidemic, which is in decline and also because of the emergence of novel forms of animal transmissible spongiform encephalopathy with zoonotic potential and the risk of nosocomial and blood transfusion-related transmission. Active surveillance has been implemented in most European countries and requires important human resources and funding. Here, we studied whether national mortality and morbidity statistics can be used as reliable indicators.

METHODS

CJD data collected by the French national CJD surveillance centre were compared with data registered in the national mortality statistics.

RESULTS

From 2000 to 2008, the two sources reported fairly similar numbers of CJD deaths. However, analysis of individual data showed important between-sources disagreement. Nearly 24% of CJD reported by the mortality register were false-positive diagnoses and 21.6% of the CJD cases diagnosed by the surveillance centre were not registered as CJD in the national mortality statistics. One out of 22 variant CJD cases was not reported as having any type of CJD in the mortality statistics.

CONCLUSIONS

These findings raise doubt about the possibility of a reliable CJD surveillance only based on mortality data.

The CALHM1 P86L polymorphism is a genetic modifier of age at onset in Alzheimer's disease: a meta-analysis study

The only established genetic determinant of non-Mendelian forms of Alzheimer's disease (AD) is the ε4 allele of the apolipoprotein E gene (APOE). Recently, it has been reported that the P86L polymorphism of the calcium homeostasis modulator 1 gene (CALHM1) is associated with the risk of developing AD. In order to independently assess this association, we performed a meta-analysis of 7,873 AD cases and 13,274 controls of Caucasian origin (from a total of 24 centers in Belgium, Finland, France, Italy, Spain, Sweden, the UK, and the USA). Our results indicate that the CALHM1 P86L polymorphism is likely not a genetic determinant of AD but may modulate age of onset by interacting with the effect of the ε4 allele of the APOE gene.

Guillain-Barre syndrome, influenzalike illnesses, and influenza vaccination during seasons with and without circulating A/H1N1 viruses

The role of influenzalike illnesses and influenza vaccination in the development of Guillain-Barré syndrome (GBS), particularly the role of A/H1N1 epidemics and A/H1N1 vaccination, is debated. Data on all incident GBS cases meeting the Brighton Collaboration criteria that were diagnosed at 25 neurology centers in France were prospectively collected between March 2007 and June 2010, covering 3 influenzavirus seasons, including the 2009-2010 A/H1N1 outbreak. A total of 457 general practitioners provided a registry of patients from which 1,080 controls were matched by age, gender, index date (calendar month), and region to 145 cases. Causal relations were assessed by multivariate case-control analysis with adjustment for risk factors (personal and family history of autoimmune disorders, among others), while matching on age, gender, and calendar time. Influenza (seasonal or A/H1N1) or influenzalike symptoms in the 2 months preceding the index date was associated with GBS, with a matched odds ratio of 2.3 (95% confidence interval (CI): 0.7, 8.2). The difference in the rates of GBS occurring between influenza virus circulation periods and noncirculation periods was highly statistically significant (P = 0.004). Adjusted odds ratios for GBS occurrence within 6 weeks after seasonal and A/H1N1 vaccination were 1.3 (95% CI: 0.4, 4.1) and 0.9 (95% CI: 0.1, 7.6), respectively. Study results confirm that influenza virus is a likely risk factor for GBS. Conversely, no new concerns have arisen regarding influenza vaccination.

Common variants at ABCA7, MS4A6A/MS4A4E, EPHA1, CD33 and CD2AP are associated with Alzheimer's disease

We sought to identify new susceptibility loci for Alzheimer's disease through a staged association study (GERAD+) and by testing suggestive loci reported by the Alzheimer's Disease Genetic Consortium (ADGC) in a companion paper. We undertook a combined analysis of four genome-wide association datasets (stage 1) and identified ten newly associated variants with P ≤ 1 × 10(-5). We tested these variants for association in an independent sample (stage 2). Three SNPs at two loci replicated and showed evidence for association in a further sample (stage 3). Meta-analyses of all data provided compelling evidence that ABCA7 (rs3764650, meta P = 4.5 × 10(-17); including ADGC data, meta P = 5.0 × 10(-21)) and the MS4A gene cluster (rs610932, meta P = 1.8 × 10(-14); including ADGC data, meta P = 1.2 × 10(-16)) are new Alzheimer's disease susceptibility loci. We also found independent evidence for association for three loci reported by the ADGC, which, when combined, showed genome-wide significance: CD2AP (GERAD+, P = 8.0 × 10(-4); including ADGC data, meta P = 8.6 × 10(-9)), CD33 (GERAD+, P = 2.2 × 10(-4); including ADGC data, meta P = 1.6 × 10(-9)) and EPHA1 (GERAD+, P = 3.4 × 10(-4); including ADGC data, meta P = 6.0 × 10(-10)).

Incidence of ischaemic stroke according to income level among older people: the 3C study

BACKGROUND

stroke has been shown to follow a social gradient with incidence rising as socioeconomic status decreases.

OBJECTIVE

to examine the relationship between socioeconomic status and ischaemic stroke risk amongst older people.

SETTING

the Cities of Bordeaux, Dijon and Montpellier in France.

SUBJECTS AND METHODS

nine thousand and two hundred and ninety-four non-institutionalised persons aged 65 years or more followed for 6 years.

RESULTS

the distribution of cardiovascular risks factors was consistent with the classical finding of more favourable risk profiles among the advantaged socioeconomic groups. One hundred and thirty-six individuals developed a first ever ischaemic stroke (incidence rate: 3.2 per 1,000 py (person-years), 95% CI 2.7-3.8). The age- and sex-adjusted incidence of ischaemic stroke increased with increasing level of income (from 2.4 to 4.1 per 1,000 py, P = 0.04). In the multivariable analysis adjusting for cardiovascular risk factors, the higher income group displayed a 80% increased risk of ischaemic stroke compared with less wealthy participants (hazards ratio 1.77, 95% CI 1.20-2.61).

CONCLUSIONS

in this community-based sample of older individuals, a higher level of household income was associated with a higher risk of ischaemic stroke, a reversal of the social gradient usually reported in younger age groups. Selective survival is one of the potential explanations for this unexpected finding.

Slow walking speed and cardiovascular death in well functioning older adults: prospective cohort study

OBJECTIVE

To study the relation between low walking speed and the risk of death in older people, both overall and with regard to the main causes of death.

DESIGN

Prospective cohort study.

SETTING

Dijon centre (France) of the Three-City study.

PARTICIPANTS

3208 men and women aged >or=65 living in the community, recruited from 1999 to 2001, and followed for an average of 5.1 years.

MAIN OUTCOME MEASURES

Mortality, overall and according to the main causes of death, by thirds of baseline walking speed (measured at maximum speed over six metres), adjusted for several potential confounders; Kaplan-Meier survival curves by thirds of baseline walking speed. Vital status during follow-up. Causes of death. Results During 16 414 person years of follow-up, 209 participants died (99 from cancer, 59 from cardiovascular disease, 51 from other causes). Participants in the lowest third of baseline walking speed had an increased risk of death (hazard ratio 1.44, 95% confidence interval 1.03 to 1.99) compared with the upper thirds. Analyses for specific causes of death showed that participants with low walking speed had about a threefold increased risk of cardiovascular death (2.92, 1.46 to 5.84) compared with participants who walked faster. There was no relation with cancer mortality (1.03, 0.65 to 1.70). In stratified analyses, cardiovascular mortality was increased across various strata defined by sex, median age, median body mass index (BMI), and level of physical activity. Conclusion Slow walking speed in older people is strongly associated with an increased risk of cardiovascular mortality.

Risk factors for progressive supranuclear palsy: a case-control study in France

BACKGROUND

The risk factors of progressive supranuclear palsy (PSP), a rare but severe Parkinsonian syndrome, are poorly known.

OBJECTIVE

To study the risk factors of PSP in a case control study among French patients.

METHOD

The study was conducted between April 2000 and December 2003. Cases were in- or outpatients of five large hospitals and fulfilled the Golbe criteria. Controls were relatives of patients from the same hospitals, free of Parkinsonian syndrome and dementia, and matched to cases for age, gender and living area. Data on demographic characteristics, occupation history, diet habits, anti-inflammatory drugs use, alcohol consumption, smoking habits, gardening and leisure activities, and exposure to pesticides were collected through a face-to-face questionnaire. A conditional logistic regression was used to analyse matched data and estimate OR.

RESULTS

79 cases and 79 controls were included. Only a few comparisons were significant. Cases reached a lower education attainment than controls (odds ratio (OR) = 2.6 (1.3 to 5.3), p = 0.01). Analysis of diet habits did not show any major difference although cases ate meat or poultry more frequently. Conversely, controls ate fruits more frequently than did cases. No association was found between PSP and occupation, use of pesticides, gardening, alcohol consumption, smoking habits and anti-inflammatory agent use.

CONCLUSION

In this case-control study, we did not find any strong environmental risk factors for PSP.

Association of plasma amyloid beta with risk of dementia: the prospective Three-City Study

OBJECTIVE

Several lines of evidence indicate that a decrease in the CSF concentration of amyloid beta(42) (Abeta(42)) is a potential biomarker for incident Alzheimer disease. In contrast, studies on plasma Abeta(1-40) and Abeta(1-42) peptide levels have yielded contradictory results. Here, we explored the links between incident dementia and plasma Abeta(1-40) and Abeta(1-42) peptide concentrations in the prospective, population-based Three-City (3C) Study. We also assessed the association between plasma concentrations of truncated Abeta (Abeta(n-40) and Abeta(n-42)) and the risk of dementia.

METHODS

During a subsequent 4-year follow-up period, 257 individuals presented incident dementia from 8,414 participants, and a subcohort of 1,185 individuals without dementia was drawn as a control cohort. Plasma levels of Abeta(1-40), Abeta(1-42), Abeta(n-40), and Abeta(n-42) were measured using an xMAP-based assay technology. The association between plasma Abeta peptide levels and the risk of dementia was assessed using Cox proportional hazard models.

RESULTS

Of the various Abeta variables analyzed, the Abeta(1-42)/Abeta(1-40) and Abeta(n-42)/Abeta(n-40) ratios presented the strongest association with the risk of dementia: people with a high Abeta(1-42)/Abeta(1-40) or Abeta(n-42)/Abeta(n-40) ratio had a lower risk of developing dementia. These associations were restricted to individuals diagnosed at 2 years of follow-up and the Abeta(n-42)/Abeta(n-40) ratio was mainly associated with the risk of mixed/vascular dementia.

CONCLUSION

Plasma Abeta peptide concentrations and Abeta(1-42)/Abeta(1-40) and Abeta(n-42)/Abeta(n-40) ratios may be useful markers to indicate individuals susceptible to short-term risk of dementia.

Apolipoprotein E genotype is related to progression of white matter lesion load

BACKGROUND AND PURPOSE

The relationship between white matter lesions (WMLs) and the apolipoprotein E genotype has been controversial from cross-sectional studies and no longitudinal finding has been reported. We investigated whether the apolipoprotein E genotype influences baseline and evolution over 4-year follow-up of WML volumes in a population-based sample of 1779 nondemented subjects aged 65 to 80 years old at enrollment.

METHODS

The sample consisted of 3C-Dijon study participants who had 2 cerebral MRIs, at entry and at 4-year follow-up. WML volumes were estimated using a fully automatic procedure. We performed analysis of covariance to evaluate the relationship between apolipoprotein E genotype and WML load and progression.

RESULTS

Multivariable analyses showed that epsilon4epsilon4 individuals had both significantly higher WML volume at baseline and higher WML increase over 4-year follow-up than noncarriers and heterozygous of the epsilon4 allele for apolipoprotein E genotype.

CONCLUSION

These findings suggest it might be important to take into account WML severity when assessing the relationship between apolipoprotein E and dementia.

[Epidemiological surveillance of Creutzfeldt-Jakob in France]

INTRODUCTION

Transmissible spongiform encephalopathies (TSE) have been under epidemiological surveillance in France and in Europe since the early 1990s. The observation of iatrogenic Creutzfeldt-Jakob disease (CJD), the outbreak of bovine spongiform encephalopathy (ESB) and its probable transmission to many species gave rise to the surveillance which remains warranted by the emergence of a variant of CJD (vCJD), in 1996.

STATE OF ART

In France, epidemiological surveillance is coordinated by the InVS which receives input from cases notifications addressed to INSERM Unit 708 directly by clinicians or more often following requests for 14-3-3 detection in CSF. All suspected cases are followed up until a final diagnosis is established. Thanks to the effectiveness of the French network of neuropathology, autopsies are performed in more than half of patients who die with a diagnosis of suspected CJD. Diagnostic criteria allow comparison of the incidence of the different forms of the disease in all countries with a system of surveillance. Sporadic CJD is the most frequent form of the disease with more than 80% of the cases. Its origin remains unknown. To date, cases of iatrogenic CJD referred to the French surveillance network have been caused by dura mater grafts or human growth hormone treatments administrated in the 1980s. Ten percent of TSE are of genetic origin with an autosomic dominant transmission of a mutation or an insertion located on the PRNP gene. The most recent form of the disease is vCJD which is a new form, first described in the United Kingdom in 1994.

PROSPECT AND CONCLUSION

Active epidemiological surveillance remains a timely issue, particularly in France, because of the development of new cases of iatrogenic CJD after human growth hormone treatment. It is of importance in France and worldwide because of the emergence of post-transfusional cases of vCJD and the possible appearance of vCJD in persons with valine-valine or methionine-valine genotypes at codon 129.

Variant Creutzfeldt-Jakob disease in France and the United Kingdom: Evidence for the same agent strain

OBJECTIVE

Variant Creutzfeldt-Jakob disease (vCJD) was first reported in the United Kingdom in 1996. Since then, the majority of cases have been observed in the United Kingdom where there was a major epidemic of bovine spongiform encephalopathy. France was the second country affected. To address the hypothesis of the involvement of a common strain of agent, we have compared clinical, neuropathological, and biochemical data on vCJD patients from both countries.

METHODS

In France and the United Kingdom, epidemiological and clinical data were obtained from analysis of medical records and direct interview of the family of the patients using the same standardized questionnaire in both countries. When brain material was available, we performed with similar methods a comparative study of brain lesions and PrP(res) glycoform ratios in both vCJD populations.

RESULTS

Clinical data, genetic background, neuropathological finding, and biochemical findings in the 185 patients observed in France (n = 23) and the United Kingdom (n = 162) were similar except for age at death. Currently, blood transfusion is a risk factor identified only in the United Kingdom.

INTERPRETATION

The close similarity between the cases of vCJD in France and the United Kingdom supports the hypothesis that a common strain of infectious agent is involved in both countries. The 5-year delay in the peak that we observed in France compared with the United Kingdom fits well with the increase in the importation of beef products to France from the United Kingdom between 1985 and 1995.

Metabolic syndrome and risk for incident Alzheimer's disease or vascular dementia: the Three-City Study

OBJECTIVE

Associations between metabolic syndrome and its individual components with risk of incident dementia and its different subtypes are inconsistent.

RESEARCH DESIGN AND METHODS

The 7,087 community-dwelling subjects aged > or =65 years were recruited from the French Three-City (3C) cohort. Hazard ratios (over 4 years) of incident dementia and its subtypes (vascular dementia and Alzheimer's disease) and association with metabolic syndrome (defined according to the National Cholesterol Education Program Adult Treatment Panel III criteria) and its individual components (hypertension, large waist circumference, high triglycerides, low HDL cholesterol, and elevated fasting glycemia) were estimated in separate Cox proportional hazard models.

RESULTS

Metabolic syndrome was present in 15.8% of the study participants. The presence of metabolic syndrome increased the risk of incident vascular dementia but not Alzheimer's disease over 4 years, independent of sociodemographic characteristics and the apolipoprotein (apo) Eepsilon4 allele. High triglyceride level was the only component of metabolic syndrome that was significantly associated with the incidence of all-cause (hazard ratio 1.45 [95% CI 1.05-2.00]; P = 0.02) and vascular (2.27 [1.16-4.42]; P = 0.02) dementia, even after adjustment of the apoE genotype. Diabetes, but not impaired fasting glycemia, was significantly associated with all-cause (1.58 [1.05-2.38]; P = 0.03) and vascular (2.53 [1.15-5.66]; P = 0.03) dementia.

CONCLUSIONS

The observed relation between high triglycerides, diabetes, and vascular dementia emphasizes the need for detection and treatment of vascular risk factors in older individuals in order to prevent the likelihood of clinical dementia.

Evaluation of the impact of memantine treatment initiation on psychotropics use: a study from the French national health care database

BACKGROUND

Clinical studies reported that treatments for Alzheimer's disease may have an impact on behavioral and psychiatric disorders. We tested the hypothesis that memantine treatment initiation modifies psychotropic medication in real-life practice patients.

METHODS

A 2-year follow-up cohort study was performed. A sample of patients treated in the general population, extracted from the database of the French national healthcare system (CNAM-TS), was examined. The sample included 4,600 memantine-treated patients (mean age 79.8 years, 69% women) randomly selected from the database of the CNAM-TS covering 69% of the French population aged 65 years and over. The follow-up rate was 95.0%. This database includes exhaustive data on drug consumption. We used interrupted time series analysis of the proportion of psychotropics users (all psychotropic drugs and specific categories) before and after onset of memantine.

RESULTS

There was a 39-50% regular increase in patients treated with psychotropic drugs before memantine initiation This increasing trend stopped after memantine initiation, the proportion of psychotropic users remaining stable around 53% up to the end. The trends before and after memantine onset were significantly different (p < 0.001).

CONCLUSIONS

Our results suggest a temporal relationship between the onset of memantine and the stabilization of psychotropic drugs use in this large sample of elderly patients.

Calf circumference is inversely associated with carotid plaques

BACKGROUND AND PURPOSE

The association of carotid atherosclerosis with body composition and fat distribution is poorly understood. We aimed to test the cross-sectional association of carotid plaques and common carotid artery intima-media thickness with calf circumference (CC), representing peripheral fat and lean mass, and with waist circumference and waist-to-hip ratio, 2 markers of abdominal obesity.

METHODS

The study was performed on 6265 subjects aged >or=65 years recruited prospectively from the electoral rolls of 3 French cities. Ultrasound examination and anthropometric measures were performed according to a standardized protocol.

RESULTS

Carotid plaques were less frequent with increasing CC, the ORs for the second, third, and fourth quartile of CC compared with the first quartile being 0.98 (95% CI, 0.84 to 1.15), 0.85 (95% CI, 0.72 to 1.01), and 0.71 (95% CI,:0.58 to 0.86; P for trend=0.0002), respectively, independently of age, gender, body mass index, and other vascular risk factors. There was an opposite and multiplicative effect of CC and waist-to-hip ratio on the frequency of carotid plaques (55.1% of individuals in the fourth waist-to-hip ratio quartile and the first CC quartile had carotid plaques, against 31.8% in the first waist-to-hip ratio and the fourth CC quartile). Mean common carotid artery intima-media thickness was larger with increasing waist circumference, waist-to-hip ratio, and CC, but the association with CC disappeared after adjusting for body mass index.

CONCLUSIONS

The present study shows, for the first time, an inverse relationship between carotid plaques and CC. Although this needs to be confirmed in other populations, it may suggest an antiatherogenic effect of large CC.

Haplotypes across ACE and the risk of Alzheimer's disease: the three-city study

The purpose of this study was to examine the impact of two polymorphisms (rs4291A>T and rs4343G>A) in the ACE gene on the risk of Alzheimer's disease (AD), using a population-based cohort of 9294 subjects selected from the electoral rolls of three French cities (the Three-City Study). Two follow-up examinations took place 2 and 4 years after inclusion. Diagnosis of dementia was assessed at baseline and at each follow-up examination by neurologists independent of the 3C Study group. For the present analysis, subjects whose mother tongue was not French, those from abroad and those lost at follow-up were excluded, leaving a sample of 6791 subjects. 108 subjects were demented at baseline and 216 subjects, among which 141 had AD, developed a dementia during follow-up. The genotype distributions of the ACE SNPs rs4291 and rs4343 did not differ according to cognitive status. After adjustment for confounding variables, the risk of developing AD was similar whatever the genotype (rs4291 AT vs TT: OR=0.90, p=0.65; AA vs TT: OR=1.05, p= 0.84; rs4343 GA vs GG: OR=1.15, p= 0.48; AA vs GG: OR=1.25, p= 0.37). No global haplotype effect could be observed on the risk of AD.

Risk factors of multiple system atrophy: a case-control study in French patients

Multiple system atrophy (MSA) is a rare sporadic progressive neurodegenerative disorder. MSA risk factors are poorly known. The objectives of this case-control study were to study environmental risk factors associated with MSA. Cases were recruited through five French referral centers. Controls matched for age, gender, and living area were recruited from healthy relatives of inpatients free of any parkinsonian syndrome of the same centers. Subjects were interviewed about exposure to environmental factors (pesticides, solvents, etc.), occupation and food habits, and use of anti-inflammatory drugs. Odds ratios and 95% confident intervals (OR [95% CI]) were computed using conditional logistic regression. Seventy-one cases and 71 matched controls were included. Low education level was more frequent in cases than in controls. Controls drank more alcohol than did cases (OR = 0.5 [0.2-1.1]) and the risk of MSA decreased with increasing alcohol consumption (P = 0.04). Controls ate fish and sea food more often and drank more tea than cases. Aspirin intake was more frequent among controls than did cases (OR = 0.5 [0.2-1.0]) and the risk of MSA decreased with the frequency of intake (P = 0.0002). MSA was not associated to exposure to pesticides, solvents, and other toxics neither to occupations, except plant and machine operators and assemblers (OR = 10.0 [2.1-47.5]) where the risk of MSA increased with number of years in this occupation (P = 0.004). This case-control study provided new findings about risk factors of MSA. On another hand, it did not confirm the previously reported association between MSA and exposure to pesticides.

White matter lesions as a predictor of depression in the elderly: the 3C-Dijon study

BACKGROUND

There is increasing evidence for a link between cerebrovascular disease and depression in the elderly but the mechanisms are still unknown. This study examines the longitudinal relationship between depression and white matter lesions (WML) in a sample of elderly aged 65 years and older.

METHODS

Three City (3C)-Dijon is a 4-year follow-up population-based prospective study of 1658 subjects. At baseline, lifetime major depressive episode diagnosis was established using the Mini International Neuropsychiatric Interview. At each study wave, severity of depressive symptoms was assessed using Center for Epidemiological Studies-Depression (CES-D), and antidepressants intake was recorded. At baseline, lifetime major depression (LMD) was defined as lifetime major depressive episode or antidepressant medication intake. At follow-up, subjects were classified "incident depression" if scoring high at CES-D or antidepressant users. At baseline, cerebral magnetic resonance imaging (MRI) was performed to quantify WML volumes using an automated method of detection. At 4-year follow-up, 1214 subjects had a second MRI.

RESULTS

Cross-sectional analysis showed a significantly higher WML volume in subjects with LMD compared with other subjects. Adjusted longitudinal analysis showed that increase in WML load was significantly higher in subjects with baseline LMD (2.1 cm(3) vs. 1.5 cm(3), p = .004). Among subjects free of depression up to baseline (n = 956), the higher the baseline WML volume, the higher the risk of developing depression during follow-up (odds ratio one quartile increase: 1.3; 95% confidence interval: = 1.1-1.7).

CONCLUSIONS

Our data show that depression and WML volumes are strongly related. These results are consistent with the hypothesis of a vascular depression in the elderly.

Factors associated with antidepressant use in depressed and non-depressed community-dwelling elderly: the three-city study

OBJECTIVES

The aim of this study was to identify factors associated with antidepressant use in non-depressed and depressed elderly persons, assuming that they varied according to clinical status.

METHODS

We studied 7,868 French community-dwelling subjects aged 65 years and over. The Center for Epidemiological Studies-Depression scale and the Mini International Neuropsychiatric Interview were used to define three groups: non-depressed, high depressive symptoms and current major depressive disorder. Separate analyses were performed to identify the factors which were associated with antidepressant use in each group.

RESULTS

Antidepressant use (55% selective serotonin re-uptake inhibitors, 25% tricyclic antidepressants, 20% other types) increased from 4.9% in non-depressed subjects to 17.3% in subjects with high depressive symptoms (HDS) and 33.6% of in those with current major depressive disorder (MDD). The factors associated with antidepressant use varied according to depression status. In particular, men with current MDD were more often treated with antidepressants than women whereas, in both the HDS and the non-depressed groups, antidepressant use was, as has been observed elsewhere, more frequent in women. Gender also had a strong modifying effect on the relationship between antidepressant use and history of major depression. Finally, the direction of the association between antidepressant use and cognitive performance varied according to depression status.

CONCLUSIONS

This study showed that the direction and strength of the association between antidepressant use and demographic and health-related factors varied according to the severity of depression symptoms. Further studies are needed to clarify the relationship between gender and cognition and antidepressant use.

Interaction between genes and environment in neurodegenerative diseases

Alzheimer's disease (AD) and Parkinson's disease (PD) are highly prevalent disorders that account for a large part of the global burden of neurodegenerative diseases. Most AD and PD cases occur sporadically and it is generally agreed that they could arise through interactions among genetic and environmental factors. Candidate genes involved in the metabolism of xenobiotics, neurodegeneration and functioning of dopaminergic neurons were found to be associated with PD. Some of these genes interact with environmental factors that could modify PD risk. Thus, we found that the inverse association between smoking and the risk of PD depended on a polymorphism of the iNOS (inducible NO synthase) gene. We also found that the cytochrome P450 2D6 gene could have a modifying effect on the risk of PD among persons exposed to pesticides. Both interactions have biological plausibility supported by laboratory studies and could contribute to better understand the aetiology of PD. A single susceptibility gene has been identified in sporadic AD. The epsilon4 allele of epsilon polymorphism of the apolipoprotein E gene (APOE) is strongly associated with AD, the risk of AD being multiplied by 5 in persons carrying two epsilon4 alleles. The mechanism of the association between APOE and AD is poorly understood. A few interactions between the epsilon polymorphism and possible risk factors for AD have been described. However, these interactions had no biological plausibility and were likely due to chance.