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author:("elba, Alexis")
1.  The protective effect of LRRK2 p.R1398H on risk of Parkinson’s disease is independent of MAPT and SNCA variants 
Neurobiology of aging  2013;35(1):10.1016/j.neurobiolaging.2013.07.013.
The best validated susceptibility variants for Parkinson’s disease (PD) are located in the alpha-synuclein (SNCA) and microtubule-associated protein tau (MAPT) genes. Recently, a protective p.N551K-R1398H-K1423K haplotype in the leucine-rich repeat kinase 2 (LRRK2) gene was identified, with p.R1398H appearing to be the most likely functional variant. To date, the consistency of the protective effect of LRRK2 p.R1398H across MAPT and SNCA variant genotypes has not been assessed. To address this, we examined four SNCA variants (rs181489, rs356219, rs11931074, rs2583988), the MAPT H1-haplotype defining variant rs1052553, and LRRK2 p.R1398H (rs7133914) in Caucasian (N=10,322) and Asian (N=2,289) series. There was no evidence of an interaction of LRRK2 p.R1398H with MAPT or SNCA variants (all P≥0.10); the protective effect of p.R1398H was observed at similar magnitude across MAPT and SNCA genotypes, and the risk effects of MAPT and SNCA variants were observed consistently for LRRK2 p.R1398H genotypes. Our results indicate that the association of LRRK2 p.R1398H with PD is independent of SNCA and MAPT variants, and vice versa, in Caucasian and Asian populations.
doi:10.1016/j.neurobiolaging.2013.07.013
PMCID: PMC3829604  PMID: 23962496
Parkinson disease; LRRK2; SNCA; MAPT; interaction; genetics
2.  Structural brain lesions and restless legs syndrome: a cross-sectional population-based study 
BMJ Open  2014;4(11):e005938.
Objective
To evaluate the association between white matter lesion (WML) volume, silent infarcts and restless legs syndrome (RLS) in a population-based study of elderly individuals.
Design
Cross-sectional study.
Setting
Population-based Three-City study.
Participants
1035 individuals from the Dijon, France, centre of the Three-City study who had available information on volume of WMLs from MRIs and who answered questions about the prevalence of RLS.
Primary outcome measure
Prevalence of RLS.
Results
WML volume was measured using an automated tissue segmentation method. Logistic regression was used to evaluate adjusted associations between tertiles of WML volume and RLS and between silent infarcts and RLS. 218 individuals (21.1%) were determined to have RLS. Compared with those in the first tertile of WML volume, individuals in the second tertile (OR=1.09; 95% CI 0.75 to 1.60) or third tertile (OR=1.17; 95% CI 0.79 to 1.74) did not have an increased prevalence of RLS. We also did not observe associations between the volume of deep or periventricular WML and RLS; nor did we observe an association between silent brain infarcts and RLS (OR=0.74; 95% CI 0.40 to 1.39). These findings were not modified by age or gender.
Conclusions
Higher volume of WML and the presence of silent infarcts were not associated with an increased prevalence of RLS in this population-based cohort of elderly individuals.
doi:10.1136/bmjopen-2014-005938
PMCID: PMC4244423  PMID: 25421338
restless legs syndrome; MRI
4.  Non-Consent to a Wrist-Worn Accelerometer in Older Adults: The Role of Socio-Demographic, Behavioural and Health Factors 
PLoS ONE  2014;9(10):e110816.
Background
Accelerometers, initially waist-worn but increasingly wrist-worn, are used to assess physical activity free from reporting-bias. However, its acceptability by study participants is unclear. Our objective is to assess factors associated with non-consent to a wrist-mounted accelerometer in older adults.
Methods
Data are from 4880 Whitehall II study participants (1328 women, age range = 60–83), requested to wear a wrist-worn accelerometer 24 h every day for 9 days in 2012/13. Sociodemographic, behavioral, and health-related factors were assessed by questionnaire and weight, height, blood pressure, cognitive and motor function were measured during a clinical examination.
Results
210 participants had contraindications and 388 (8.3%) of the remaining 4670 participants did not consent. Women, participants reporting less physical activity and less favorable general health were more likely not to consent. Among the clinical measures, cognitive impairment (Odds Ratio = 2.21, 95% confidence interval: 1.22–4.00) and slow walking speed (Odds Ratio = 1.38, 95% confidence interval: 1.02–1.86) were associated with higher odds of non-consent.
Conclusions
The rate of non-consent in our study of older adults was low. However, key markers of poor health at older ages were associated with non-consent, suggesting some selection bias in the accelerometer data.
doi:10.1371/journal.pone.0110816
PMCID: PMC4208789  PMID: 25343453
5.  Association of body mass index and waist circumference with successful ageing: 16 year follow-up of the Whitehall II study 
Obesity (Silver Spring, Md.)  2013;22(4):1172-1178.
Objective
We examined whether midlife body mass index (BMI) and waist circumference (WC) predict successful ageing.
Design and Methods
BMI/WC were assessed in 4869 persons (mean age 51.2, range 42–63 in 1991/93) and survival and successful ageing (alive, no chronic disease at age >60 years, not in the worst age- and sex-standardized quintile of cognitive, physical, respiratory, and cardiovascular, and mental health) ascertained over a 16-year follow-up, analysed using logistic regression adjusted for socio-demographic factors and health behaviours.
Results
507 participants died, 1008 met the criteria for successful ageing. Those with BMI≥30 kg/m2 had lower odds of successful ageing (Odds Ratio (OR)=0.37; 95% Confidence Interval (CI): 0.27, 0.50) and survival (OR=0.55; 95% CI: 0.41, 0.74) compared to BMI between 18.5–25 kg/m2. Those with a large waist circumference (≥102/88 cm in men/women) had lower odds of successful ageing (OR=0.41; 95% CI: 0.31, 0.54) and survival (OR=0.57; 95% CI: 0.44, 0.73) compared to those with a small waist (<94/80 cm in men/women). Analysis with finer categories showed lower odds of successful ageing starting at BMI ≥23.5 kg/m2 and waist circumference 82/68 cm in men/women.
Conclusions
Optimal midlife BMI and waist circumference for successful ageing might be substantially below the current thresholds used to define obesity.
doi:10.1002/oby.20651
PMCID: PMC3968224  PMID: 24167036
obesity; body mass index; waist circumference; ageing
6.  No evidence of a longitudinal association between diurnal cortisol patterns and cognition☆ 
Neurobiology of Aging  2014;35(10):2239-2245.
We examined the effect of salivary cortisol on cognitive performance and decline in 3229 adults (79% men), mean age 61 years. Six saliva samples over the day along with a cognition test battery were administered twice in 5 years. In fully-adjusted cross-sectional analyses from 2002 to 2004, higher waking cortisol was associated with higher reasoning score (β = 0.08, 95% confidence interval: 0.01, 0.15) but this finding was not replicated using data from 2007 to 2009. Over the mean 5 years follow-up there was decline in all cognitive tests but this decline did not vary as a function of cortisol levels; the exception was among APOE e4 carriers where a flatter diurnal slope and higher bedtime cortisol were associated with faster decline in verbal fluency. Changes in cortisol measures between 2002/2004 and 2007/2009 or chronically elevated levels were not associated with cognitive performance in 2007/2009. These results, based on a large sample of community-dwelling adults suggest that variability in hypothalamic-pituitary-adrenal function is not a strong contributor to cognitive aging.
doi:10.1016/j.neurobiolaging.2014.03.015
PMCID: PMC4099515  PMID: 24735831
Cortisol; Glucocorticoid; Cognitive decline
7.  Population-specific frequencies for LRRK2 susceptibility variants in the Genetic Epidemiology Of Parkinson’s Disease (GEO-PD) consortium 
Variants within the leucine-rich repeat kinase 2 gene are recognized as the most frequent genetic cause of Parkinson’s disease. Leucine-rich repeat kinase 2 variation related to susceptibility to disease displays many features that reflect the nature of complex late-onset sporadic disorders, such as Parkinson’s disease. The Genetic Epidemiology of Parkinson’s disease consortium recently performed the largest genetic association study for variants in the leucine-rich repeat kinase 2 gene across 23 different sites in 15 countries. Herein we detail the allele frequencies for the novel risk factors (p.A419V and p.M1646T) and the protective haplotype (p.N551K-R1398H-K1423K) reported in the original publication. Simple population allele frequencies can not only provide an insight into the clinical relevance of specific variants but also help genetically define patient groups. Establishing individual patient-based genomic susceptibility profiles incorporating both risk and protective factors will determine future diagnostic and treatment strategies.
doi:10.1002/mds.25600
PMCID: PMC4108155  PMID: 23913756
Parkinson disease; LRRK2; genetics; association study
8.  Increased risk of coronary heart disease among individuals reporting adverse impact of stress on their health: the Whitehall II prospective cohort study 
European Heart Journal  2013;34(34):2697-2705.
Aim
Response to stress can vary greatly between individuals. However, it remains unknown whether perceived impact of stress on health is associated with adverse health outcomes. We examined whether individuals who report that stress adversely affects their health are at increased risk of coronary heart disease (CHD) compared with those who report that stress has no adverse health impact.
Methods and results
Analyses are based on 7268 men and women (mean age: 49.5 years, interquartile range: 11 years) from the British Whitehall II cohort study. Over 18 years of follow-up, there were 352 coronary deaths or first non-fatal myocardial infarction (MI) events. After adjustment for sociodemographic characteristics, participants who reported at baseline that stress has affected their health ‘a lot or extremely’ had a 2.12 times higher (95% CI 1.52–2.98) risk of coronary death or incident non-fatal MI when compared with those who reported no effect of stress on their health. This association was attenuated but remained statistically significant after adjustment for biological, behavioural, and other psychological risk factors including perceived stress levels, and measures of social support; fully adjusted hazard ratio: 1.49 (95% CI 1.01–2.22).
Conclusions
In this prospective cohort study, the perception that stress affects health, different from perceived stress levels, was associated with an increased risk of coronary heart disease. Randomized controlled trials are needed to determine whether disease risk can be reduced by increasing clinical attention to those who complain that stress greatly affects their health.
doi:10.1093/eurheartj/eht216
PMCID: PMC3766148  PMID: 23804585
Epidemiology; Stress; Coronary heart disease; Prospective studies
9.  Interleukin-6 and C-reactive protein as predictors of cognitive decline in late midlife 
Neurology  2014;83(6):486-493.
Objective:
Peripheral inflammatory markers are elevated in patients with dementia. In order to assess their etiologic role, we examined whether interleukin-6 (IL-6) and C-reactive protein (CRP) measured in midlife predict concurrently assessed cognition and subsequent cognitive decline.
Methods:
Mean value of IL-6 and CRP, assessed on 5,217 persons (27.9% women) in 1991–1993 and 1997–1999 in the Whitehall II longitudinal cohort study, were categorized into tertiles to examine 10-year decline (assessments in 1997–1999, 2002–2004, and 2007–2009) in standardized scores (mean = 0, SD = 1) of memory, reasoning, and verbal fluency using mixed models. Mini-Mental State Examination (MMSE) was administered in 2002–2004 and 2007–2009; decline ≥3 points was modeled with logistic regression. Analyses were adjusted for baseline age, sex, education, and ethnicity; further analyses were also adjusted for smoking, obesity, Framingham cardiovascular risk score, and chronic diseases (cancer, coronary heart disease, stroke, diabetes, and depression).
Results:
In cross-sectional analysis, reasoning was 0.08 SD (95% confidence interval [CI] −0.14, −0.03) lower in participants with high compared to low IL-6. In longitudinal analysis, 10-year decline in reasoning was greater (ptrend = 0.01) among participants with high IL-6 (−0.35; 95% CI −0.37, −0.33) than those with low IL-6 (−0.29; 95% CI −0.31, −0.27). In addition, participants with high IL-6 had 1.81 times greater odds ratio of decline in MMSE (95% CI 1.20, 2.71). CRP was not associated with decline in any test.
Conclusions:
Elevated IL-6 but not CRP in midlife predicts cognitive decline; the combined cross-sectional and longitudinal effects over the 10-year observation period corresponded to an age effect of 3.9 years.
doi:10.1212/WNL.0000000000000665
PMCID: PMC4141998  PMID: 24991031
10.  Predicting cognitive decline 
Neurology  2013;80(14):1300-1306.
Objective:
Our aim was to compare 2 Framingham vascular risk scores with a dementia risk score in relation to 10-year cognitive decline in late middle age.
Methods:
Participants were men and women with mean age of 55.6 years at baseline, from the Whitehall II study, a longitudinal British cohort study. We compared the Framingham general cardiovascular disease risk score and the Framingham stroke risk score with the Cardiovascular Risk Factors, Aging and Dementia (CAIDE) risk score that uses risk factors in midlife to estimate risk of late-life dementia. Cognitive tests included reasoning, memory, verbal fluency, vocabulary, and global cognition, assessed 3 times over 10 years.
Results:
Higher cardiovascular disease risk and higher stroke risk were associated with greater cognitive decline in all tests except memory; higher dementia risk was associated with greater decline in reasoning, vocabulary, and global cognitive scores. Compared with the dementia risk score, cardiovascular and stroke risk scores showed slightly stronger associations with 10-year cognitive decline; these differences were statistically significant for semantic fluency and global cognitive scores. For example, cardiovascular disease risk was associated with −0.06 SD (95% confidence interval [CI] = −0.08, −0.05) decline in the global cognitive scores over 10 years whereas dementia risk was associated with −0.03 SD (95% CI = −0.04, −0.01) decline (difference in β coefficients = 0.03; 95% CI = 0.01, 0.05).
Conclusions:
The CAIDE dementia and Framingham risk scores predict cognitive decline in late middle age but the Framingham risk scores may have an advantage over the dementia risk score for use in primary prevention for assessing risk of cognitive decline and targeting of modifiable risk factors.
doi:10.1212/WNL.0b013e31828ab370
PMCID: PMC3656460  PMID: 23547265
11.  Midlife type 2 diabetes and poor glycaemic control as risk factors for cognitive decline in early old age: a post-hoc analysis of the Whitehall II cohort study 
Summary
Background
Type 2 diabetes increases the risk for dementia, but whether it affects cognition before old age is unclear. We investigated whether duration of diabetes in late midlife and poor glycaemic control were associated with accelerated cognitive decline.
Methods
5653 participants from the Whitehall II cohort study (median age 54·4 years [IQR 50·3–60·3] at first cognitive assessment), were classified into four groups: normoglycaemia, prediabetes, newly diagnosed diabetes, and known diabetes. Tests of memory, reasoning, phonemic and semantic fluency, and a global score that combined all cognitive tests, were assessed three times over 10 years (1997–99, 2002–04, and 2007–09). Mean HbA1c was used to assess glycaemic control during follow-up. Analyses were adjusted for sociodemographic characteristics, health-related behaviours, and chronic diseases.
Findings
Compared with normoglycaemic participants, those with known diabetes had a 45% faster decline in memory (10 year difference in decline −0·13 SD, 95% CI −0·26 to −0·00; p=0·046), a 29% faster decline in reasoning (−0·10 SD, −0·19 to −0·01; p=0·026), and a 24% faster decline in the global cognitive score (−0·11 SD, −0·21 to −0·02; p=0·014). Participants with prediabetes or newly diagnosed diabetes had similar rates of decline to those with normoglycaemia. Poorer glycaemic control in participants with known diabetes was associated with a significantly faster decline in memory (−0·12 [–0·22 to −0·01]; p=0·034) and a decline in reasoning that approached significance (−0·07 [–0·15 to 0·00]; p=0·052).
Interpretation
The risk of accelerated cognitive decline in middle-aged patients with type 2 diabetes is dependent on both disease duration and glycaemic control.
Funding
US National Institutes of Health, UK Medical Research Council.
doi:10.1016/S2213-8587(13)70192-X
PMCID: PMC4274502  PMID: 24622753
12.  Trajectories of the Framingham general cardiovascular risk profile in midlife and poor motor function later in life: The Whitehall II study☆☆☆ 
Background
Vascular risk factors are associated with increased risk of cognitive impairment and dementia, but their association with motor function, another key feature of aging, has received little research attention. We examined the association between trajectories of the Framingham general cardiovascular disease risk score (FRS) over midlife and motor function later in life.
Methods
A total of 5376 participants of the Whitehall II cohort study (29% women) who had up to four repeat measures of FRS between 1991–1993 (mean age = 48.6 years) and 2007–2009 (mean age = 65.4 years) and without history of stroke or coronary heart disease in 2007–2009 were included. Motor function was assessed in 2007–2009 through objective tests (walking speed, chair rises, balance, finger tapping, grip strength). We used age- and sex-adjusted linear mixed models.
Results
Participants with poorer performances for walking speed, chair rises, and balance in 2007–2009 had higher FRS concurrently and also in 1991–1993, on average 16 years earlier. These associations were robust to adjustment for cognition, socio-economic status, height, and BMI, and not explained by incident mobility limitation prior to motor assessment. No association was found with finger tapping and grip strength.
Conclusions
Cardiovascular risk early in midlife is associated with poor motor performances later in life. Vascular risk factors play an important and under-recognized role in motor function, independently of their impact on cognition, and suggest that better control of vascular risk factors in midlife may prevent physical impairment and disability in the elderly.
doi:10.1016/j.ijcard.2013.12.051
PMCID: PMC3991855  PMID: 24461963
CVD, cardiovascular disease; FRS, Framingham general cardiovascular disease risk score; SES, socioeconomic status; BMI, body mass index; SD, standard deviation; Cardiovascular risk score; Motor function; Aging; Stroke; Cohort study
13.  Association Between Questionnaire- and Accelerometer-Assessed Physical Activity: The Role of Sociodemographic Factors 
American Journal of Epidemiology  2014;179(6):781-790.
The correlation between objective and self-reported measures of physical activity varies between studies. We examined this association and whether it differed by demographic factors or socioeconomic status (SES). Data were from 3,975 Whitehall II (United Kingdom, 2012–2013) participants aged 60–83 years, who completed a physical activity questionnaire and wore an accelerometer on their wrist for 9 days. There was a moderate correlation between questionnaire- and accelerometer-assessed physical activity (Spearman's r = 0.33, 95% confidence interval: 0.30, 0.36). The correlations were higher in high-SES groups than in low-SES groups (P 's = 0.02), as defined by education (r = 0.38 vs. r = 0.30) or occupational position (r = 0.37 vs. r = 0.29), but did not differ by age, sex, or marital status. Of the self-reported physical activity, 68.3% came from mild activities, 25% from moderate activities, and only 6.7% from vigorous activities, but their correlations with accelerometer-assessed total physical activity were comparable (range of r 's, 0.21–0.25). Self-reported physical activity from more energetic activities was more strongly associated with accelerometer data (for sports, r = 0.22; for gardening, r = 0.16; for housework, r = 0.09). High-SES persons reported more energetic activities, producing stronger accelerometer associations in these groups. Future studies should identify the aspects of physical activity that are most critical for health; this involves better understanding of the instruments being used.
doi:10.1093/aje/kwt330
PMCID: PMC3939851  PMID: 24500862
accelerometry; cohort studies; elderly; epidemiologic methods; physical activity; questionnaires
14.  Motor function in the elderly 
Neurology  2013;81(5):417-426.
Objective:
The reserve hypothesis accounts for the lack of direct relationship between brain pathology and its clinical manifestations. Research has mostly focused on cognition; our objective is to examine whether the reserve hypothesis applies to motor function. We investigated whether education, a marker of reserve, modifies the association between white matter lesions (WMLs), a marker of vascular brain damage, and maximum walking speed (WS), an objective measure of motor function. We also examined the cross-sectional and longitudinal association between education and WS.
Methods:
Data are from 4,010 participants aged 65–85 years in the longitudinal Three-City–Dijon Study with up to 4 WS measures over 10 years. We examined the interaction between education and WMLs for baseline WS. We studied the association between education and repeated WS measures using linear mixed models, and the role of covariates in explaining the education-WS association.
Results:
Education was strongly associated with baseline WS; the difference in mean WS between the high and low education groups (0.145 m/s, 95% confidence interval = 0.125–0.165) was equivalent to 7.4 years of age. WMLs were associated with slow WS only in the low education group (p interaction = 0.026). WS declined significantly over time (−0.194 m/s/10 years, 95% confidence interval = −0.206, −0.182), but education did not influence rate of decline. Anthropometric characteristics, parental education, general health, and cognition had the strongest role in explaining the baseline education-WS association.
Conclusions:
Participants with more education were less susceptible to WMLs' effect on motor function. Higher education was associated with better motor performances but not with motor decline. These results are consistent with the passive reserve hypothesis.
doi:10.1212/WNL.0b013e31829d8761
PMCID: PMC3776533  PMID: 23803317
15.  Alcohol consumption and cognitive decline in early old age 
Neurology  2014;82(4):332-339.
Objective:
To examine the association between alcohol consumption in midlife and subsequent cognitive decline.
Methods:
Data are from 5,054 men and 2,099 women from the Whitehall II cohort study with a mean age of 56 years (range 44–69 years) at first cognitive assessment. Alcohol consumption was assessed 3 times in the 10 years preceding the first cognitive assessment (1997–1999). Cognitive tests were repeated in 2002–2004 and 2007–2009. The cognitive test battery included 4 tests assessing memory and executive function; a global cognitive score summarized performances across these tests. Linear mixed models were used to assess the association between alcohol consumption and cognitive decline, expressed as z scores (mean = 0, SD = 1).
Results:
In men, there were no differences in cognitive decline among alcohol abstainers, quitters, and light or moderate alcohol drinkers (<20 g/d). However, alcohol consumption ≥36 g/d was associated with faster decline in all cognitive domains compared with consumption between 0.1 and 19.9 g/d: mean difference (95% confidence interval) in 10-year decline in the global cognitive score = −0.10 (−0.16, −0.04), executive function = −0.06 (−0.12, 0.00), and memory = −0.16 (−0.26, −0.05). In women, compared with those drinking 0.1 to 9.9 g/d of alcohol, 10-year abstainers showed faster decline in the global cognitive score (−0.21 [−0.37, −0.04]) and executive function (−0.17 [−0.32, −0.01]).
Conclusions:
Excessive alcohol consumption in men (≥36 g/d) was associated with faster cognitive decline compared with light to moderate alcohol consumption.
doi:10.1212/WNL.0000000000000063
PMCID: PMC3929201  PMID: 24431298
16.  Impact of smoking on cognitive decline in early old age: the Whitehall II cohort study 
Archives of General Psychiatry  2012;69(6):627-635.
Context
Smoking is a possible risk factor for dementia although its impact may have been underestimated in elderly populations due to the shorter lifespan of smokers.
Objective
To examine the association between smoking history and cognitive decline in the transition from midlife to old age.
Design, Setting, and Participants
Data are from 5099 men and 2137 women in the Whitehall II study, mean age 56 years (range=44–69 years) at the first cognitive assessment (1997–1999), repeated over 2002–2004 and 2007–2009.
Main Outcome Measures
The cognitive test battery was composed of tests of memory, vocabulary, executive function (composed of one reasoning and two fluency tests), and a global cognitive score summarising performance across all five tests. Smoking status was assessed over the entire study period. Linear mixed models were used to assess the association between smoking history and 10-year cognitive decline, expressed as z-scores.
Results
In men, 10-year cognitive decline in all tests except vocabulary among never smokers ranged from a quarter to a third of the baseline standard deviation. Faster cognitive decline was observed among current smokers compared to never smokers in men [mean difference in 10-year decline in global cognition=−0.09 (95%CI:−0.15;−0.03) and executive function=−0.11 (−0.17;−0.05)]. Recent ex-smokers had greater decline in executive function (−0.08 (−0.14;−0.02)) while the decline in long-term ex-smokers was similar to that among never smokers. In analyses that additionally took drop-out and death into account, these differences were 1.2 to 1.5 times larger. In women, cognitive decline did not vary as a function of smoking status.
Conclusions
Compared to never smokers, middle-aged male smokers experienced faster cognitive decline in global cognition and executive function. In ex-smokers with at least 10-year cessation there were no adverse effects on cognitive decline.
doi:10.1001/archgenpsychiatry.2011.2016
PMCID: PMC3675806  PMID: 22309970
Adult; Aged; Cognition Disorders; etiology; physiopathology; Cohort Studies; Female; Great Britain; Humans; Male; Middle Aged; Neuropsychological Tests; Smoking; adverse effects; Time Factors
17.  Association between Blood Lead and Walking Speed in the National Health and Nutrition Examination Survey (NHANES 1999–2002) 
Environmental Health Perspectives  2013;121(6):711-716.
Background: Walking speed is a simple and reliable measure of motor function that is negatively associated with adverse health events in older people, including falls, disability, hospital admissions, and mortality. Lead has adverse affects on human health, particularly on the vascular and neurological systems.
Objective: We explored the hypothesis that lead is associated with slower walking speed.
Methods: We used U.S. National Health and Nutrition Examination Survey (NHANES) cross-sectional data from 1999–2002. The time to walk 20 ft (walking speed) was measured among 1,795 men and 1,798 women ≥ 50 years of age. The association between walking speed and quintiles of blood lead concentration was estimated separately in men and women using linear regression models adjusted for age, education, ethnicity, alcohol use, smoking status, height, and waist circumference.
Results: Mean blood lead concentrations and walking speeds were 2.17 μg/dL and 3.31 ft/sec in women, and 3.18 μg/dL and 3.47 ft/sec in men, respectively. Among women, walking speed decreased with increasing quintiles of blood lead, resulting in an estimated mean value that was 0.11 ft/sec slower (95% CI: –0.19, –0.04; p-trend = 0.005) for women with blood lead concentrations in the highest versus lowest quintile. In contrast, lead was not associated with walking speed in men.
Conclusion: Blood lead concentration was associated with decreased walking speed in women, but not in men. Our results contribute to the growing evidence that lead exposure, even at low levels, is detrimental to public health.
doi:10.1289/ehp.1205918
PMCID: PMC3672915  PMID: 23603014
environmental epidemiology; gait speed; lead; NHANES; toxicant; walking speed
18.  Obesity phenotypes in midlife and cognition in early old age 
Neurology  2012;79(8):755-762.
Objective:
To examine the association of body mass index (BMI) and metabolic status with cognitive function and decline.
Methods:
A total of 6,401 adults (71.2% men), aged 39–63 years in 1991–1993, provided data on BMI (normal weight 18.5–24.9 kg/m2, overweight 25–29.9 kg/m2; and obese ≥30 kg/m2) and metabolic status (abnormality defined as 2 or more of 1) triglycerides ≥1.69 mmol/L or lipid-lowering drugs, 2) systolic blood pressure ≥130 mm Hg, diastolic blood pressure ≥85 mm Hg, or antihypertensive drugs, 3) glucose ≥5.6 mmol/L or medications for diabetes, and 4) high-density lipoprotein cholesterol <1.04 mmol/L for men and <1.29 mmol/L for women). Four cognitive tests (memory, reasoning, semantic, and phonemic fluency) were administered in 1997–1999, 2002–2004, and 2007–2009, standardized to z scores, and averaged to yield a global score.
Results:
Of the participants, 31.0% had metabolic abnormalities, 52.7% were normal weight, 38.2% were overweight, and 9.1% were obese. Among the obese, the global cognitive score at baseline (p = 0.82) and decline (p = 0.19) over 10 years was similar in the metabolically normal and abnormal groups. In the metabolically normal group, the 10-year decline in the global cognitive score was similar (p for trend = 0.36) in the normal weight (−0.40; 95% confidence interval [CI] −0.42 to −0.38), overweight (−0.42; 95% CI −0.45 to −0.39), and obese (−0.42; 95% CI −0.50 to −0.34) groups. However, in the metabolically abnormal group, the decline on the global score was faster among obese (−0.49; 95% CI −0.55 to −0.42) than among normal weight individuals (−0.42; 95% CI −0.50 to −0.34), (p = 0.03).
Conclusions:
In these analyses the fastest cognitive decline was observed in those with both obesity and metabolic abnormality.
doi:10.1212/WNL.0b013e3182661f63
PMCID: PMC3421151  PMID: 22915175
19.  Common variants at 12q14 and 12q24 are associated with hippocampal volume 
Bis, Joshua C. | DeCarli, Charles | Smith, Albert Vernon | van der Lijn, Fedde | Crivello, Fabrice | Fornage, Myriam | Debette, Stephanie | Shulman, Joshua M. | Schmidt, Helena | Srikanth, Velandai | Schuur, Maaike | Yu, Lei | Choi, Seung-Hoan | Sigurdsson, Sigurdur | Verhaaren, Benjamin F.J. | DeStefano, Anita L. | Lambert, Jean-Charles | Jack, Clifford R. | Struchalin, Maksim | Stankovich, Jim | Ibrahim-Verbaas, Carla A. | Fleischman, Debra | Zijdenbos, Alex | den Heijer, Tom | Mazoyer, Bernard | Coker, Laura H. | Enzinger, Christian | Danoy, Patrick | Amin, Najaf | Arfanakis, Konstantinos | van Buchem, Mark A. | de Bruijn, Renée F.A.G. | Beiser, Alexa | Dufouil, Carole | Huang, Juebin | Cavalieri, Margherita | Thomson, Russell | Niessen, Wiro J. | Chibnik, Lori B. | Gislason, Gauti K. | Hofman, Albert | Pikula, Aleksandra | Amouyel, Philippe | Freeman, Kevin B. | Phan, Thanh G. | Oostra, Ben A. | Stein, Jason L. | Medland, Sarah E. | Vasquez, Alejandro Arias | Hibar, Derrek P. | Wright, Margaret J. | Franke, Barbara | Martin, Nicholas G. | Thompson, Paul M. | Nalls, Michael A. | Uitterlinden, Andre G. | Au, Rhoda | Elbaz, Alexis | Beare, Richard J. | van Swieten, John C. | Lopez, Oscar | Harris, Tamara B. | Chouraki, Vincent | Breteler, Monique M.B. | De Jager, Philip L. | Becker, James T. | Vernooij, Meike W. | Knopman, David | Fazekas, Franz | Wolf, Philip A. | van der Lugt, Aad | Gudnason, Vilmundur | Longstreth, W.T. | Brown, Mathew A. | Bennett, David A. | van Duijn, Cornelia M. | Mosley, Thomas H. | Schmidt, Reinhold | Tzourio, Christophe | Launer, Lenore J. | Ikram, M. Arfan | Seshadri, Sudha
Nature genetics  2012;44(5):545-551.
Aging is associated with reductions in hippocampal volume (HV) that are accelerated by Alzheimer’s disease and vascular risk factors. Our genome-wide association study of dementia-free persons (n=9,232) identified 46 SNPs at four loci with p-values <4.0×10-7. Two additional samples (n=2,318) replicated associations at 12q24 within MSRB3/WIF1 (discovery + replication, rs17178006; p=5.3×10-11) and at 12q14 near HRK/FBXW8 (rs7294919; p=2.9×10-11). Remaining associations included one 2q24 SNP within DPP4 (rs6741949; p=2.9×10-7) and nine 9p33 SNPs within ASTN2 (rs7852872; p=1.0×10-7) that were also associated with HV (p<0.05) in a third younger, more heterogeneous sample (n=7,794). The ASTN2 SNP was also associated with decline in cognition in a largely independent sample (n=1,563). These associations implicate genes related to apoptosis (HRK), development (WIF1), oxidative stress (MSR3B), ubiquitination (FBXW8), enzymes targeted by new diabetes medications (DPP4), and neuronal migration (ASTN2), indicating novel genetic influences that influence hippocampal size and possibly the risk of cognitive decline and dementia.
doi:10.1038/ng.2237
PMCID: PMC3427729  PMID: 22504421
20.  LRRK2 exonic variants and susceptibility to Parkinson’s disease 
Lancet neurology  2011;10(10):898-908.
Background
Leucine-rich repeat kinase 2 (LRRK2) is known to harbor highly penetrant mutations linked to familial parkinsonism. However, its full polymorphic variability in relationship to Parkinson’s disease (PD) risk has not been systematically assessed.
Methods
We examined the frequency pathogenicity of 121 exonic LRRK2 variants in three ethnic series (Caucasian [N=12,590], Asian [N=2,338] and Arab-Berber [N=612]) consisting of 8,611 patients and 6,929 control subjects from 23 separate sites of the Genetic Epidemiology of Parkinson’s Disease Consortium.
Findings
Excluding carriers of previously known pathogenic mutations, new independent risk associations were found for polymorphic variants in Caucasian (p.M1646T, OR: 1.43, 95% CI: 1.15 – 1.78, P=0.0012) and Asian (p.A419V, OR: 2.27, 95% CI: 1.35 – 3.83, P=0.0011) populations. In addition, a protective haplotype was observed at >5% frequency (p.N551K-p.R1398H-p.K1423K) in the Caucasian and Asian series’, with a similar finding in the small Arab-Berber series that requires further study (combined 3-series OR: 0.82, 95% CI: 0.72 – 0.94, P=0.0043). Of the two previously reported Asian risk variants p.G2385R was found to be associated with disease (OR: 1.73, 95% CI: 1.20 – 2.49, P=0.0026) but no association was observed for p.R1628P (OR: 0.62, 95% CI: 0.36 – 1.07, P=0.087). Also in the Arab-Berber series, p.Y2189C showed potential evidence of risk association with PD (OR: 4.48, 95% CI: 1.33 – 15.09, P=0.012). Of note, two variants (p.I1371V and p.T2356I) which have been previously proposed as pathogenic were observed in patient and control subjects at the same frequency.
Interpretation
LRRK2 offers an example where multiple rare and common genetic variants in the same gene have independent effects on disease risk. Lrrk2, and the pathway in which it functions, is important in the etiology and pathogenesis of a greater proportion of patients with PD than previously believed.
Funding
The present study and original funding for the GEO-PD Consortium was supported by grants from Michael J. Fox Foundation. Studies at individual sites were supported by a number of funding agencies world-wide.
doi:10.1016/S1474-4422(11)70175-2
PMCID: PMC3208320  PMID: 21885347
Parkinson disease; LRRK2; genetics
21.  Association of lung function with physical, mental and cognitive function in early old age 
Age  2010;33(3):385-392.
Lung function predicts mortality; whether it is associated with functional status in the general population remains unclear. This study examined the association of lung function with multiple measures of functioning in early old age. Data are drawn from the Whitehall II study; data on lung function (forced expiratory volume in 1 s, height FEV1), walking speed (2.44 m), cognitive function (memory and reasoning) and self-reported physical and mental functioning (SF-36) were available on 4,443 individuals, aged 50–74 years. In models adjusted for age, 1 standard deviation (SD) higher height-adjusted FEV1 was associated with greater walking speed (beta = 0.16, 95% CI: 0.13, 0.19), memory (beta = 0.09, 95% CI: 0.06, 0.12), reasoning (beta = 0.16, 95% CI: 0.13, 0.19) and self-reported physical functioning (beta = 0.13, 95% CI: 0.10, 0.16). Socio-demographic measures, health behaviours (smoking, alcohol, physical activity, fruit/vegetable consumption), body mass index (BMI) and chronic conditions explained two-thirds of the association with walking speed and self-assessed physical functioning and over 80% of the association with cognitive function. Our results suggest that lung function is a good ‘summary’ measure of overall functioning in early old age.
doi:10.1007/s11357-010-9189-x
PMCID: PMC3168608  PMID: 20878489
Ageing; Lung function; Cognitive function; Physical function
22.  Association of lung function with physical, mental and cognitive function in early old age 
Age  2010;33(3):385-392.
Lung function predicts mortality, whether it is associated with functional status in the general population remains unclear. This study examined the association of lung function with multiple measures of functioning in early old age. Data are drawn from the Whitehall II study; data on lung function (forced expiratory volume in one second, height FEV1), walking speed (over 2.44 m), cognitive function (memory and reasoning), and self-reported physical and mental functioning (SF-36) were available on 4443 individuals, aged 50–74 years. In models adjusted for age, one standard deviation (SD) higher height-adjusted FEV1 was associated with greater walking speed (beta=0.16, 95% CI: 0.13, 0.19), memory (beta=0.09, 95% CI: 0.06, 0.12), reasoning (beta=0.16, 95% CI: 0.13, 0.19), and self-reported physical functioning (beta=0.13, 95% CI: 0.10, 0.16). Socio-demographic measures, health behaviours (smoking, alcohol, physical activity, fruit/vegetable consumption), BMI and chronic conditions explained two-thirds of the association with walking speed and self-assessed physical functioning and over 80% of the association with cognitive function. Our results suggest that lung function is a good “summary” measure of overall functioning in early old age.
doi:10.1007/s11357-010-9189-x
PMCID: PMC3168608  PMID: 20878489
Aged; Aging; physiology; psychology; Cognition; physiology; Female; Health Status; Humans; Lung; physiology; Male; Middle Aged; Spirometry; Walking; physiology; ageing; lung function; cognitive function; physical function
23.  Independent and joint effects of the MAPT and SNCA genes in Parkinson's disease 
Annals of neurology  2011;69(5):778-792.
Objective
We studied the independent and joint effects of the genes encoding alpha-synuclein (SNCA) and microtubule associated protein tau (MAPT) in Parkinson's disease (PD) as part of a large meta-analysis of individual data from case-control studies participating in the Genetic Epidemiology of Parkinson's Disease (GEO-PD) consortium.
Methods
Participants of Caucasian ancestry were genotyped for a total of four SNCA (rs2583988, rs181489, rs356219, rs11931074) and two MAPT (rs1052553, rs242557) SNPs. Individual and joint effects of SNCA and MAPT SNPs were investigated using fixed- and random-effects logistic regression models. Interactions were studied both on a multiplicative and an additive scale, and using a case-control and case-only approach.
Results
Fifteen GEO-PD sites contributed a total of 5302 cases and 4161 controls. All four SNCA SNPs and the MAPT H1-haplotype defining SNP (rs1052553) displayed a highly significant marginal association with PD at the significance level adjusted for multiple comparisons. For SNCA, the strongest associations were observed for SNPs located at the 3′ end of the gene. There was no evidence of statistical interaction between any of the four SNCA SNPs and rs1052553 or rs242557, neither on the multiplicative nor on the additive scale.
Interpretation
This study confirms the association between PD and both SNCA SNPs and the H1 MAPT haplotype. It shows, based on a variety of approaches, that the joint action of variants in these two loci is consistent with independent effects of the genes without additional interacting effects.
doi:10.1002/ana.22321
PMCID: PMC3082599  PMID: 21391235
Parkinson disease; SNCA; MAPT; genetics; interaction; case-control
24.  Association of walking speed in late midlife with mortality: results from the Whitehall II cohort study 
Age  2012;35(3):943-952.
Slow walking speed is associated with increased mortality in the elderly, but it is unknown whether a similar association is present in late midlife. Our aim was to examine walking speed in late midlife as a predictor of mortality, as well as factors that may explain this association. Data are drawn from the Whitehall II longitudinal cohort study of British civil servants. The analyses are based on 6,266 participants (29% women; mean age = 61 years, SD = 6) for whom “walking speed at usual pace” was measured over 8 ft (2.44 m) at baseline. Participants were followed for all-cause and cause-specific mortalities during a mean of 6.4 (SD = 0.8) years. During this period, 227 participants died. Participants in the bottom sex-specific third of walking speed (men, <1.26 m/s; women, <1.09 m/s) had an increased risk of death compared to those in the middle and top thirds (age- and sex-adjusted hazard ratio = 1.89, 95% confidence interval (CI) = 1.45–2.46), with no evidence of effect modification by age or sex (interactions, P ≥ 0.40). The association between walking speed and mortality was partially explained by baseline inflammatory markers (percentage reduction of the association 22.8%), height and body mass index (16.6%), chronic diseases (14.0%), and health behaviors (13.4%). Together these and other baseline factors (socioeconomic status, cardiovascular risk factors, cognitive function) explained 48.5% of the association (adjusted hazard ratio = 1.39, 95% CI = 1.04–1.84). In conclusion, walking speed measured in late midlife seems to be an important marker of mortality risk; multiple factors, in particular inflammatory markers, partially explain this association.
Electronic supplementary material
The online version of this article (doi:10.1007/s11357-012-9387-9) contains supplementary material, which is available to authorized users.
doi:10.1007/s11357-012-9387-9
PMCID: PMC3636402  PMID: 22361996
Walking speed; Mortality; Inflammation; Cohort study; Epidemiology
25.  Why Does Lung Function Predict Mortality? Results From the Whitehall II Cohort Study 
American Journal of Epidemiology  2010;172(12):1415-1423.
The authors examined the extent to which socioeconomic position, behavior-related factors, cardiovascular risk factors, inflammatory markers, and chronic diseases explain the association between poor lung function and mortality in 4,817 participants (68.9% men) from the Whitehall II Study aged 60.8 years (standard deviation, 5.9), on average. Forced expiratory volume in 1 second (FEV1) was used to measure lung function in 2002–2004. A total of 139 participants died during a mean follow-up period of 6.4 years (standard deviation, 0.8). In a model adjusted for age and sex, being in the lowest tertile of FEV1/height2 was associated with a 1.92-fold (95% confidence interval: 1.35, 2.73) increased risk of mortality compared with being in the top 2 tertiles. Once age, sex, and smoking history were taken into account, the most important explanatory factors for this association were inflammatory markers (21.3% reduction in the FEV1/height2-mortality association), coronary heart disease, stroke, and diabetes (11.7% reduction), and alcohol consumption, diet, physical activity, and body mass index (9.8% reduction). The contribution of socioeconomic position and cardiovascular risk factors was small (≤3.5% reduction). Taken together, these factors explained 32.5% of the association. Multiple pathways link lung function to mortality; these results show inflammatory markers to be particularly important.
doi:10.1093/aje/kwq294
PMCID: PMC2998200  PMID: 20961971
forced expiratory volume; inflammation; middle aged; mortality; respiratory function tests

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