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1.  Adipose Tissue Density, a Novel Biomarker Predicting Mortality Risk in Older Adults 
Knowledge of adipose composition in relation to mortality may help delineate inconsistent relationships between obesity and mortality in old age. We evaluated relationships between abdominal visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) density, mortality, biomarkers, and characteristics.
VAT and SAT density were determined from computed tomography scans in persons aged 65 and older, Health ABC (n = 2,735) and AGES-Reykjavik (n = 5,131), and 24 nonhuman primates (NHPs). Associations between adipose density and mortality (4–13 years follow-up) were assessed with Cox proportional hazards models. In NHPs, adipose density was related to serum markers and tissue characteristics.
Higher density adipose tissue was associated with mortality in both studies with adjustment for risk factors including adipose area, total fat, and body mass index. In women, hazard ratio and 95% CI for the densest quintile (Q5) versus least dense (Q1) for VAT density were 1.95 (1.36–2.80; Health ABC) and 1.88 (1.31–2.69; AGES-Reykjavik) and for SAT density, 1.76 (1.35–2.28; Health ABC) and 1.56 (1.15–2.11; AGES-Reykjavik). In men, VAT density was associated with mortality in Health ABC, 1.52 (1.12–2.08), whereas SAT density was associated with mortality in both Health ABC, 1.58 (1.21–2.07), and AGES-Reykjavik, 1.43 (1.07–1.91). Higher density adipose tissue was associated with smaller adipocytes in NHPs. There were no consistent associations with inflammation in any group. Higher density adipose tissue was associated with lower serum leptin in Health ABC and NHPs, lower leptin mRNA expression in NHPs, and higher serum adiponectin in Health ABC and NHPs.
VAT and SAT density provide a unique marker of mortality risk that does not appear to be inflammation related.
PMCID: PMC3859360  PMID: 23707956
Obesity; Aging; Leptin; Adiponectin.
2.  Different susceptibility of medial temporal lobe and basal ganglia atrophy rates to vascular risk factors 
Neurobiology of aging  2013;35(1):72-78.
Atrophy of medial temporal lobe (MTL) and basal ganglia (BG) are characteristic of various neurodegenerative diseases in older people. In search of potentially modifiable factors that lead to atrophy in these structures, we studied the association of vascular risk factors to atrophy of MTL and BG in 368 non-demented men and women [b. 1907–1935] who participated in the Age, Gene/Environment, Susceptibility - Reykjavik Study. A fully automated segmentation pipeline estimated volumes of MTL and BG from whole brain MRI performed at baseline and 2.4 years later. Linear regression models showed higher systolic and diastolic blood pressures and the presence of Apo E ε4 were independently associated with increased atrophy of MTL but no association of vascular risk factors with atrophy of BG. The different susceptibility of MTL and BG atrophy to the presence of vascular risk factors suggests the relatively preserved perfusion of BG when vascular risk factors are present.
PMCID: PMC3802531  PMID: 23992618
Medial temporal lobe; hippocampus; basal ganglia; thalamus; atrophy; aging; vascular risk factors
3.  Associations of current and remitted major depressive disorder with brain atrophy: the AGES-Reykjavik Study 
Psychological medicine  2012;43(2):317-328.
To examine whether lifetime DSM-IV diagnosis of major depressive disorder (MDD), including age at onset and number of episodes, is associated with brain atrophy in older persons without dementia.
Within the population-based AGES-Reykjavik Study 4,354 persons (mean age 76±5 years, 58% women) without dementia had a 1.5Tesla brain MRI. Automated brain segmentation total and regional brain volumes were calculated. History of MDD, including age at onset and number of episodes, and MDD in the past 2 weeks was diagnosed according to DSM-IV criteria using the MINI International Neuropsychiatric Interview.
Of the total sample, 4.5% reported a lifetime history of MDD; 1.5% had a current diagnosis of MDD (including 75% with a prior history of depression) and 3.0% had a past but no current diagnosis (remission). After adjusting for multiple covariates, compared to participants never depressed, those with current MDD (irrespective of past) had more global brain atrophy (B=−1.25%; 95%CI −2.05 to −0.44%), including more gray and white matter atrophy in most lobes as well as more atrophy of the hippocampus and thalamus. Participants with current, first onset, MDD also had more brain atrophy (B=−1.62%; 95%CI −3.30 to 0.05%), while those remitted did not (B=0.06%; 95%CI −0.54 to 0.66%).
In older persons without dementia, current MDD, irrespective of prior history, but not remitted MDD, was associated with widespread gray and white matter brain atrophy. Prospective studies should examine whether MDD is a consequence of or contributes to brain volume loss and development of dementia.
PMCID: PMC4244840  PMID: 22647536
4.  Structural patterns of the proximal femur in relation to age and hip fracture risk in women 
Bone  2013;57(1):10.1016/j.bone.2013.08.017.
Fractures of the proximal femur are the most devastating outcome of osteoporosis. It is generally understood that age-related changes in hip structure confer increased risk, but there have been few explicit comparisons of such changes in healthy subjects to those with hip fracture. In this study, we used quantitative computed tomography and tensor-based morphometry (TBM) to identify three-dimensional internal structural patterns of the proximal femur associated with age and with incident hip fracture. A population-based cohort of 349 women representing a broad age range (21–97 years) were included in this study, along with a cohort of 222 older women (mean age 79±7 years) with (n=74) and without (n=148) incident hip fracture. Images were spatially normalized to a standardized space, and age- and fracture-specific morphometric features were identified based on statistical maps of shape features described as local changes of bone volume. Morphometric features were visualized as maps of local contractions and expansions, and significance was displayed as Student’s t-test statistical maps. Significant age-related changes included local expansions of regions low in volumetric bone mineral density (vBMD) and local contractions of regions high in vBMD. Some significant fracture-related features resembled an accentuated aging process, including local expansion of the superior aspect of the trabecular bone compartment in the femoral neck, with contraction of the adjoining cortical bone. However, other features were observed only in the comparison of hip fracture subjects with age-matched controls including focal contractions of the cortical bone at the superior aspect of the femoral neck, the lateral cortical bone just inferior to the greater trochanter, and the anterior intertrochanteric region. Results of this study support the idea that the spatial distribution of morphometric features is relevant to age-related changes in bone and independently to fracture risk. In women, the identification by TBM of fracture-specific morphometric alterations of the proximal femur, in conjunction with vBMD and clinical risk factors, may improve hip fracture prediction.
PMCID: PMC3809121  PMID: 23981658
Osteoporosis; proximal femur; statistical parametric mapping; tensor-based morphometry (TBM); age; fracture
5.  Similarities and differences between sexes in regional loss of cortical and trabecular bone in the mid-femoral neck: The AGES-Reykjavik Longitudinal Study 
The risk of hip fracture rises rapidly with age, and is notably higher in women. After falls and prior fragility fractures, the main clinically recognized risk factor for hip fracture is reduced bone density. To better understand the extent to which femoral neck density and structure change with age in each sex, we have carried out a longitudinal study in subjects not treated with agents known to influence bone mineral density to investigate changes in regional cortical thickness, as well as cortical and trabecular bone mineral density at the mid-femoral neck. Segmental QCT analysis was used to assess bone measurements in two anatomic sub-regions, the supero-lateral (superior) and infero-medial (inferior). A total of 400 older individuals (100 men and 300 women, aged 66–90 years) who were participants in the AGES-Reykjavik study, were studied. Participants had two QCT scans of the hip over a median follow-up of 5.1 yr. (mean baseline age 74 yr.). Changes in bone values during follow-up were estimated from mixed effects regression models. At baseline women had lower bone values in the superior region than men. At follow-up all bone values were lower in women, except cortical vBMD inferiorly. The relative losses in all bone values estimated in the superior region were substantially (about threefold) and significantly greater compared to those estimated in the inferior region in both sexes. Women lost cortical thickness and cortical vBMD more rapidly than men in both regions; and this was only weakly reflected in total femoral neck DXA-like results. The higher rate of bone loss in women at critical locations may contribute materially to the greater femoral neck fracture incidence among women than men.
PMCID: PMC3779495  PMID: 23609070
Cortical thickness; proximal end of femur; aging; longitudinal; QCT
6.  Prevalence and Prognosis of Unrecognized Myocardial Infarction Determined by Cardiac Magnetic Resonance in Older Adults 
Unrecognized myocardial infarction (MI) is prognostically important but electrocardiography (ECG), the main epidemiology tool for detection, is insensitive to MI.
Determine prevalence and mortality risk for unrecognized MI (UMI) detected by cardiac magnetic resonance (CMR) or ECG.
ICELAND MI is a cohort substudy of the Age, Gene/Environment Susceptibility-Reykjavik Study (enrollment January 2004–January 2007) using ECG or CMR to detect UMI.
Community dwelling participants in Iceland over age 67.
936 participants (ages 67–93 years) including 670 who were randomly selected and 266 with diabetes.
Main Outcome Measures
MI prevalence and mortality through September 1, 2011. Results reported with 95% confidence limits and net reclassification improvement (NRI).
Of 936 participants, 91 had recognized MI (RMI; 9.7% CI 8–12%), and 157 had UMI by CMR (17%; CI 14–19%) which was more prevalent than the 46 UMI by ECG (5%; CI 4–6%, p<0.001). Diabetic participants had more UMI by CMR than UMI by ECG (n=72; 21%; CI 17–26% vs. n=15; 4%; CI 2–7%, p<0.001). UMI by CMR was associated with atherosclerosis risk factors, coronary calcium, coronary revascularization, and peripheral vascular disease. Over a median of 6.4 years, 33% (CI 23–43%) of individuals with RMI died (30 of 91) and 28% (CI 21–35%) with UMI died (44 of 157), both higher rates than the 17% (CI 15–20%) with no MI that died (119 of 688). UMI by CMR improved risk stratification for mortality over RMI (NRI: 0.34; CI 0.16–0.53). Adjusting for age, sex, diabetes, and RMI, UMI by CMR remained associated with mortality (HR 1.45 CI 1.02–2.06, absolute risk increase (ARI) 8%) and significantly improved risk stratification for mortality, NRI 0.16 (CI 0.01–0.31)) but UMI by ECG did not (HR 0.88, CI 0.45–1.73 ARI −2%; NRI: −0.05; CI −0.17–0.05). Compared to those with RMI, participants with UMI by CMR used cardiac medications such as statins less often (36%; CI, 28–43% or 56/157 vs.73%; CI 63–82% or 66/91; p<0.001).
In a community-based cohort, the prevalence of UMI by CMR was higher than the prevalence of recognized MI or UMI by ECG, and was associated with increased mortality risk.
PMCID: PMC4137910  PMID: 22948699
7.  Migraine, depression, and brain volume 
Neurology  2013;80(23):2138-2144.
To examine the joint association of migraine headache and major depressive disorder on brain volume in older persons without dementia.
Participants (n = 4,296, 58% women) from the population-based Age, Gene/Environment Susceptibility–Reykjavik Study were assessed for migraine headache in 1967–1991 (age 51 years [range 33–65]) according to modified International Classification of Headache Disorders–II criteria. In 2002–2006 (age 76 years [range 66–96]), lifetime history of major depressive disorder (depression) was diagnosed according to DSM-IV criteria, and full-brain MRI was acquired, which was computer postprocessed into total brain volume (TBV) (gray matter [GM], white matter [WM], white matter hyperintensities) and CSF volume for each study subject. We compared brain tissue volumes by headache categories with or without depression using linear regression, adjusting for intracranial volume and other factors.
Compared with the reference group (no headache, no depression) TBV and WM and GM volumes were smaller in those with both migraine and depression (TBV −19.2 mL, 95% confidence interval [CI] −35.3, −3.1, p = 0.02; WM −12.8 mL, CI −21.3, −4.3, p = 0.003; GM −13.0 mL, CI −26.0, 0.1, p = 0.05) but not for those with migraine alone (TBV 0.4 mL, WM 0.2 mL, GM 0.6 mL) or depression alone (TBV −3.9 mL, WM −0.9 mL, GM −2.9 mL).
Reporting both migraine and major depressive disorder was associated with smaller brain tissue volumes than having one or neither of these conditions. Migraineurs with depression may represent a distinct clinical phenotype with different long-term sequelae. Nonetheless, the number of subjects in the current study is relatively small and these findings need to be confirmed in future studies.
PMCID: PMC3716352  PMID: 23700334
8.  Propensity to Work Among Chronically Unemployed Adult Drug Users 
Substance use & misuse  2010;46(5):599-607.
Analyses were conducted to compare rates of employment before, during, and after employment at the therapeutic workplace, which is a novel employment-based treatment for drug misuse. Participants in two clinical trials attended the therapeutic workplace at higher rates than they worked before intake and six months after discharge. These data suggest that unemployed chronic drug misusers will attend work at higher rates at the therapeutic workplace than in the community when paid modest wages, and that the failure of chronic drug misusers to obtain employment in the community may not result from lack of interest in work.
PMCID: PMC3985271  PMID: 20964531
drug misuse; employment; therapeutic workplace; vocational training
9.  Motivating Ergonomic Computer Workstation Setup: Sometimes Training Is Not Enough 
Musculoskeletal disorders lead to pain and suffering and result in high costs to industry. There is evidence to suggest that whereas conventional ergonomics training programs result in knowledge gains, they may not necessarily translate to changes in behavior. There were 11 participants in an ergonomics training program, and a subsample of participants received a motivational intervention in the form of incentives for correct workstation setup. Training did not yield any changes in ergonomics measures for any participant. Incentives resulted in marked and durable changes in targeted workstation measures. The data suggest that improving worker knowledge about ergonomically correct workstation setup does not necessarily lead to correct workstation setup, and that motivational interventions may be needed to achieve lasting behavior change.
PMCID: PMC3985273  PMID: 22429527
computer workstations; incentives; injury prevention; musculoskeletal disorders; training
10.  Barriers to Employment among Unemployed Drug Users: Age Predicts Severity 
Drug users in treatment or exiting treatment face many barriers to employment when entering the job market, such as low levels of education and technical skills, and low levels of interpersonal skills. As a result of these and other barriers, employment rates in these groups are generally low.
This article examines the existence and possible predictors of specific barriers to employment related to interpersonal and technical skills in a sample of participants enrolled in a therapeutic workplace intervention for substance abuse.
In Study I (N = 77), we characterized and examined predictors of participant scores on a staff-rated scale of interpersonal skills (Work Behavior Inventory). In Study II (N = 29), we examined whether participants had lower levels of computer knowledge than job seekers in the general population, and investigated possible predictors of computer knowledge in the sample.
In general, participants in Study I displayed low levels of interpersonal skills, and participants in Study II scored lower on the computer knowledge test than job seekers in the general population. Older participants tended to have lower levels of interpersonal skills and lower levels of computer knowledge.
Conclusions and Scientific Significance
These results suggest that providers of workforce development services for drug users in treatment or exiting treatment should attend to these specific barriers to employment, which may also be more pronounced among older clients.
PMCID: PMC3985289  PMID: 22242680
computer skills; employment; employment barriers; social skills; substance abuse
11.  Atrial fibrillation is associated with reduced brain volume and cognitive function independent of cerebral infarcts 
Background and Purpose
Atrial fibrillation (AF) has been associated with cognitive decline independant of stroke, suggesting additional effects of AF on the brain. We aimed to assess the association between AF and brain function and structure in a general elderly population.
This is a cross-sectional analysis on 4251 non-demented participants (mean age 76 ± 5 years) in the population-based AGES-Reykjavik Study. Medical record data were collected on the presence, subtype and time from first diagnosis of AF; 330 participants had AF. Brain volume measurements, adjusted for intracranial volume, and presence of cerebral infarcts were determined with MRI. Memory, speed of processing and executive function composites were calculated from a cognitive test battery. In a multivariable linear regression model, adjustments were made for demographic, cardiovascular risk factors and cerebral infarcts.
Participants with AF had lower total brain volume compared to those without AF (p<0.001). The association was stronger with persistent/permanent than paroxysmal AF and with increased time from the first diagnosis of the disease. Of the brain tissue volumes, AF was associated with lower volume of gray and white matter (p<0.001 and p=0.008 respectively) but not of white matter hyperintesities (p=0.49). Participants with AF scored lower on tests on memory.
AF is associated with smaller brain volume and the association is stronger with increasing burden of the arrhythmia. These findings suggest that AF has a cumulative negative effect on the brain independent of cerebral infarcts.
PMCID: PMC3632359  PMID: 23444303
atrial fibrillation; brain imaging; cognition; cerebral infarct
12.  Hip Fractures and Bone Mineral Density in the Elderly—Importance of Serum 25-Hydroxyvitamin D 
PLoS ONE  2014;9(3):e91122.
The significance of serum 25-hydroxyvitamin D [25(OH)D] concentrations for hip fracture risk of the elderly is still uncertain. Difficulties reaching both frail and healthy elderly people in randomized controlled trials or large cohort studies may in part explain discordant findings. We determined hazard ratios for hip fractures of elderly men and women related to serum 25(OH)D, including both the frail and the healthy segment of the elderly population.
The AGES-Reykjavik Study is a prospective study of 5764 men and women, age 66–96 years, based on a representative sample of the population of Reykjavik, Iceland. Participation was 71.8%. Hazard ratios of incident hip fractures and baseline bone mineral density were determined according to serum concentrations of 25(OH)D at baseline.
Mean follow-up was 5.4 years. Compared with referent values (50–75 nmol/L), hazard ratios for hip fractures were 2.24 (95% CI 1.63, 3.09) for serum 25(OH)D <30 nmol/L, adjusting for age, sex, body mass index, height, smoking, alcohol intake and season, and 2.08 (95% CI 1.51, 2.87), adjusting additionally for physical activity. No difference in risk was associated with 30–50 nmol/L or ≥75 nmol/L in either model compared with referent. Analyzing the sexes separately, hazard ratios were 2.61 (95% CI 1.47, 4.64) in men and 1.93 (95% CI 1.31, 2.84) in women. Values <30 nmol/L were associated with significantly lower bone mineral density of femoral neck compared with referent, z-scores -0.14 (95% CI −0.27, −0.00) in men and −0.11 (95% CI −0.22, −0.01) in women.
Our results lend support to the overarching importance of maintaining serum 25(OH)D above 30 nmol/L for bone health of elderly people while potential benefits of having much higher levels could not be detected.
PMCID: PMC3951316  PMID: 24621578
13.  Proximal femoral density distribution and structure in relation to age and hip fracture risk in women 
Hip fracture risk rises exponentially with age, but there is little knowledge about how fracture-related alterations in hip structure differ from those of aging. We employed computed tomography (CT) imaging to visualize the three-dimensional (3D) spatial distribution of bone mineral density (BMD) in the hip in relation to age- and incident hip fracture. We used inter-subject image registration to integrate 3D hip CT images into a statistical atlas comprising women aged 21-97 years (n=349) and a group of women with (n=74) and without (n=148) incident hip fracture 4-7 years after their imaging session. Voxel-based morphometry was used to generate Student’s t-test statistical maps from the atlas, which indicated regions that were significantly associated with age or with incident hip fracture. Scaling factors derived from inter-subject image registration were employed as measures of bone size. BMD comparisons of young, middle-aged, and older American women showed preservation of load-bearing cortical and trabecular structures with aging, whereas extensive bone loss was observed in other trabecular and cortical regions. In contrast, comparisons of older Icelandic fracture women with age-matched controls showed that hip fracture was associated with a global cortical bone deficit, including both the superior cortical margin and the load-bearing inferior cortex. Bone size comparisons showed larger dimensions in older compared to younger American women and in older Icelandic fracture women compared to controls. The results indicate that older Icelandic women who sustain incident hip fracture have a structural phenotype that cannot be described as an accelerated pattern of normal age-related loss. The fracture-related cortical deficit noted in this study may provide a biomarker of increased hip fracture risk that may be translatable to DXA and other clinical images.
PMCID: PMC3578081  PMID: 23109068
Osteoporosis; proximal femur; statistical parametric mapping; age; fracture
14.  Cerebral microbleeds and age-related macular degeneration: The AGES-Reykjavik Study 
Neurobiology of aging  2012;33(12):2935-2937.
We test the hypothesis that cerebral microbleeds (CMB) and age-related macular degeneration (AMD), both linked to amyloid-β deposition, are correlated. This study includes 4205 participants (mean age 76.2; 57.8% women) in the AGES-Reykjavik Study (2002–2006). CMB were assessed from magnetic resonance images and AMD from digital retinal images. Data were analyzed with multinomial logistic models controlling for major confounders. Evidence of CMB was detected in 476 persons (272 with strict lobar CMB and 204 with non-lobar CMB). AMD was detected in 1098 persons (869 with early AMD, 140 with exudative AMD, and 89 with pure geographic atrophy). Early and exudative AMD were not associated with CMB. The adjusted odds ratio of pure geographic atrophy was 1.62 (95% confidence interval 0.93–2.82, P=0.089) for having any CMB, 1.43 (0.66–3.06, P=0.363) for strict lobar CMB, and 1.85 (0.89–3.87, P=0.100) for non-lobar CMB. This study provides no evidence that amyloid deposits in the brain and AMD are correlated. However, the suggestive association of geographic atrophy with CMB warrants further investigation.
PMCID: PMC3368038  PMID: 22382405
Age-related macular degeneration; Cerebral microbleeds; Amyloid-β; The AGES-Reykjavik Study
15.  Maintenance of reinforcement to address the chronic nature of drug addiction 
Preventive medicine  2012;55(Suppl):S46-S53.
Drug addiction can be a chronic problem. Abstinence reinforcement can initiate drug abstinence, but as with other treatments many patients relapse after the intervention ends. Abstinence reinforcement can be maintained to promote long-term drug abstinence, but practical means of implementing long-term abstinence reinforcement are needed.
We reviewed 8 clinical trials conducted in Baltimore, MD from 1996 through 2010 that evaluated the therapeutic workplace as a vehicle for maintaining reinforcement for the treatment of drug addiction. The therapeutic workplace uses employment-based reinforcement in which employees must provide objective evidence of drug abstinence or medication adherence to work and earn wages.
Employment-based reinforcement can initiate (3 of 4 studies) and maintain (2 studies) cocaine abstinence in methadone patients, although relapse can occur even after long-term exposure to abstinence reinforcement (1 study). Employment-based reinforcement can also promote abstinence from alcohol in homeless alcohol dependent adults (1 study), and maintain adherence to extended-release naltrexone in opioid dependent adults (2 studies).
Treatments should seek to promote life-long effects in patients. Therapeutic reinforcement may need to be maintained indefinitely to prevent relapse. Workplaces could be effective vehicles for the maintenance of therapeutic reinforcement contingencies for drug abstinence and adherence to addiction medications.
PMCID: PMC3437006  PMID: 22668883
Reinforcement; Incentives; Contingency Management; Cocaine; Heroin; Drug Addiction; Treatment; Employment; Poverty; Relapse
16.  Genetic Associations with Valvular Calcification and Aortic Stenosis 
The New England journal of medicine  2013;368(6):503-512.
Limited information is available regarding genetic contributions to valvular calcification, which is an important precursor of clinical valve disease.
We determined genomewide associations with the presence of aorticvalve calcification (among 6942 participants) and mitral annular calcification (among 3795 participants), as detected by computed tomographic (CT) scanning; the study population for this analysis included persons of white European ancestry from three cohorts participating in the Cohorts for Heart and Aging Research in Genomic Epidemiology consortium (discovery population). Findings were replicated in independent cohorts of persons with either CT-detected valvular calcification or clinical aortic stenosis.
One SNP in the lipoprotein(a) (LPA) locus (rs10455872) reached genomewide significance for the presence of aorticvalve calcification (odds ratio per allele, 2.05; P = 9.0×10−10), a finding that was replicated in additional white European, African-American, and Hispanic-American cohorts (P<0.05 for all comparisons). Genetically determined Lp(a) levels, as predicted by LPA genotype, were also associated with aorticvalve calcification, supporting a causal role for Lp(a). In prospective analyses, LPA genotype was associated with incident aortic stenosis (hazard ratio per allele, 1.68; 95% confidence interval [CI], 1.32 to 2.15) and aortic-valve replacement (hazard ratio, 1.54; 95% CI, 1.05 to 2.27) in a large Swedish cohort; the association with incident aortic stenosis was also replicated in an independent Danish cohort. Two SNPs (rs17659543 and rs13415097) near the proinflammatory gene IL1F9 achieved genomewide significance for mitral annular calcification (P = 1.5×10−8 and P = 1.8×10−8, respectively), but the findings were not replicated consistently.
Genetic variation in the LPA locus, mediated by Lp(a) levels, is associated with aorticvalve calcification across multiple ethnic groups and with incident clinical aortic stenosis. (Funded by the National Heart, Lung, and Blood Institute and others.)
PMCID: PMC3766627  PMID: 23388002
17.  Coronary artery calcium distributions in older persons in the AGES-Reykjavik study 
European journal of epidemiology  2012;27(9):673-687.
Coronary Artery Calcium (CAC) is a sign of advanced atherosclerosis and an independent risk factor for cardiac events. Here, we describe CAC-distributions in an unselected aged population and compare modelling methods to characterize CAC-distribution. CAC is difficult to model because it has a skewed and zero inflated distribution with over-dispersion. Data are from the AGES-Reykjavik sample, a large population based study [2002-2006] in Iceland of 5,764 persons aged 66-96 years.
Linear regressions using logarithmic- and Box-Cox transformations on CAC+1, quantile regression and a Zero-Inflated Negative Binomial model (ZINB) were applied. Methods were compared visually and with the PRESS-statistic, R2 and number of detected associations with concurrently measured variables.
There were pronounced differences in CAC according to sex, age, history of coronary events and presence of plaque in the carotid artery. Associations with conventional coronary artery disease (CAD) risk factors varied between the sexes.
The ZINB model provided the best results with respect to the PRESS-statistic, R2, and predicted proportion of zero scores. The ZINB model detected similar numbers of associations as the linear regression on ln(CAC+1) and usually with the same risk factors.
PMCID: PMC3746182  PMID: 22990371
Coronary artery calcium; epidemiology; older persons; skewed distribution; ZINB; statistical modelling
18.  Common variants at 6q22 and 17q21 are associated with intracranial volume 
Nature genetics  2012;44(5):539-544.
During aging, intracranial volume remains unchanged and represents maximally attained brain size, while various interacting biological phenomena lead to brain volume loss. Consequently, intracranial volume and brain volume in late life reflect different genetic influences. Our genome-wide association study in 8,175 community-dwelling elderly did not reveal any genome-wide significant associations (p<5*10−8) for brain volume. In contrast, intracranial volume was significantly associated with two loci: rs4273712 (p=3.4*10−11), a known height locus on chromosome 6q22, and rs9915547, tagging the inversion on chromosome 17q21 (p=1.5*10−12). We replicated the associations of these loci with intracranial volume in a separate sample of 1,752 older persons (p=1.1*10−3 for 6q22 and p=1.2*10−3 for 17q21). Furthermore, we also found suggestive associations of the 17q21 locus with head circumference in 10,768 children (mean age 14.5 months). Our data identify two loci associated with head size, with the inversion on 17q21 also likely involved in attaining maximal brain size.
PMCID: PMC3618290  PMID: 22504418
19.  Type 3 finger length pattern is associated with total knee replacements due to osteoarthritis but not with hip replacements or hand osteoarthritis in the elderly: The AGES-Reykjavik study 
Recent case–control studies have shown an association between type 3 finger length pattern (longer ring finger than index finger) and knee osteoarthritis. This large cross-sectional study tests the hypothesis that the type 3 pattern is associated with total joint replacements due to osteoarthritis in a large population based study.
Finger length ratios were assessed visually on 5170 hand photographs (2975 females, 2195 males, mean age 76). In this population-based multidisciplinary study of aging in Reykjavik, Iceland, the prevalence of osteoarthritis associated total knee replacements was 223(4.3%) and total hip replacements 316(6.1%). We then performed a binary logistic regression analysis for total knee replacements and total hip replacements, including finger length patterns, osteoarthritis at other sites and other variables with possible association to osteoarthritis such as age, BMI and bone mineral density of the spine.
The prevalence of the type 3 pattern was 50% (43% in females, 58% in males). The regression analysis revealed an odds ratio for total knee replacements of 1.65 (1.24-2.2) p = 0.0007, in the type 3 finger pattern group, similar in both genders. This association was independent of the associations we have previously reported between total knee replacements and BMI and the presence of hand osteoarthritis. No association was seen between finger length patterns and total hip replacements.
Finger length patterns read from digital photographs in this large study confirm previous radiographic observations with significant associations between the type 3 pattern and total knee replacements but not total hip replacements in both genders in this elderly group.
PMCID: PMC3626925  PMID: 23530906
Osteoarthritis; Finger length ratio; Epidemiology
20.  Common Genetic Variation in the 3-BCL11B Gene Desert Is Associated With Carotid-Femoral Pulse Wave Velocity and Excess Cardiovascular Disease Risk The AortaGen Consortium 
Mitchell, Gary F. | Verwoert, Germaine C. | Tarasov, Kirill V. | Isaacs, Aaron | Smith, Albert V. | Yasmin | Rietzschel, Ernst R. | Tanaka, Toshiko | Liu, Yongmei | Parsa, Afshin | Najjar, Samer S. | O’Shaughnessy, Kevin M. | Sigurdsson, Sigurdur | De Buyzere, Marc L. | Larson, Martin G. | Sie, Mark P.S. | Andrews, Jeanette S. | Post, Wendy S. | Mattace-Raso, Francesco U.S. | McEniery, Carmel M. | Eiriksdottir, Gudny | Segers, Patrick | Vasan, Ramachandran S. | van Rijn, Marie Josee E. | Howard, Timothy D. | McArdle, Patrick F. | Dehghan, Abbas | Jewell, Elizabeth | Newhouse, Stephen J. | Bekaert, Sofie | Hamburg, Naomi M. | Newman, Anne B. | Hofman, Albert | Scuteri, Angelo | De Bacquer, Dirk | Ikram, Mohammad Arfan | Psaty, Bruce | Fuchsberger, Christian | Olden, Matthias | Wain, Louise V. | Elliott, Paul | Smith, Nicholas L. | Felix, Janine F. | Erdmann, Jeanette | Vita, Joseph A. | Sutton-Tyrrell, Kim | Sijbrands, Eric J.G. | Sanna, Serena | Launer, Lenore J. | De Meyer, Tim | Johnson, Andrew D. | Schut, Anna F.C. | Herrington, David M. | Rivadeneira, Fernando | Uda, Manuela | Wilkinson, Ian B. | Aspelund, Thor | Gillebert, Thierry C. | Van Bortel, Luc | Benjamin, Emelia J. | Oostra, Ben A. | Ding, Jingzhong | Gibson, Quince | Uitterlinden, André G. | Abecasis, Gonçalo R. | Cockcroft, John R. | Gudnason, Vilmundur | De Backer, Guy G. | Ferrucci, Luigi | Harris, Tamara B. | Shuldiner, Alan R. | van Duijn, Cornelia M. | Levy, Daniel | Lakatta, Edward G. | Witteman, Jacqueline C.M.
Carotid-femoral pulse wave velocity (CFPWV) is a heritable measure of aortic stiffness that is strongly associated with increased risk for major cardiovascular disease events.
Methods and Results
We conducted a meta-analysis of genome-wide association data in 9 community-based European ancestry cohorts consisting of 20,634 participants. Results were replicated in 2 additional European ancestry cohorts involving 5,306 participants. Based on a preliminary analysis of 6 cohorts, we identified a locus on chromosome 14 in the 3′-BCL11B gene desert that is associated with CFPWV (rs7152623, minor allele frequency = 0.42, beta=−0.075±0.012 SD/allele, P = 2.8 x 10−10; replication beta=−0.086±0.020 SD/allele, P = 1.4 x 10−6). Combined results for rs7152623 from 11 cohorts gave beta=−0.076±0.010 SD/allele, P=3.1x10−15. The association persisted when adjusted for mean arterial pressure (beta=−0.060±0.009 SD/allele, P = 1.0 x 10−11). Results were consistent in younger (<55 years, 6 cohorts, N=13,914, beta=−0.081±0.014 SD/allele, P = 2.3 x 10−9) and older (9 cohorts, N=12,026, beta=−0.061±0.014 SD/allele, P=9.4x10−6) participants. In separate meta-analyses, the locus was associated with increased risk for coronary artery disease (hazard ratio [HR]=1.05, confidence interval [CI]=1.02 to 1.08, P=0.0013) and heart failure (HR=1.10, CI=1.03 to 1.16, P=0.004).
Common genetic variation in a locus in the BCL11B gene desert that is thought to harbor one or more gene enhancers is associated with higher CFPWV and increased risk for cardiovascular disease. Elucidation of the role this novel locus plays in aortic stiffness may facilitate development of therapeutic interventions that limit aortic stiffening and related cardiovascular disease events.
PMCID: PMC3288392  PMID: 22068335
aorta; arterial stiffness; pulse wave velocity; genetics; cardiovascular disease
21.  Genome-wide Association Study for Coronary Artery Calcification with Follow-up in Myocardial Infarction 
Circulation  2011;124(25):2855-2864.
Coronary artery calcification (CAC) detected by computed tomography is a non-invasive measure of coronary atherosclerosis, that underlies most cases of myocardial infarction (MI). We aimed to identify common genetic variants associated with CAC and further investigate their associations with MI.
Methods and Results
Computed tomography was used to assess quantity of CAC. A meta-analysis of genome-wide association studies for CAC was carried out in 9,961 men and women from five independent community-based cohorts, with replication in three additional independent cohorts (n=6,032). We examined the top single nucleotide polymorphisms (SNPs) associated with CAC quantity for association with MI in multiple large genome-wide association studies of MI. Genome-wide significant associations with CAC for SNPs on chromosome 9p21 near CDKN2A and CDKN2B (top SNP: rs1333049, P=7.58×10−19) and 6p24 (top SNP: rs9349379, within the PHACTR1 gene, P=2.65×10−11) replicated for CAC and for MI. Additionally, there is evidence for concordance of SNP associations with both CAC and with MI at a number of other loci, including 3q22 (MRAS gene), 13q34 (COL4A1/COL4A2 genes), and 1p13 (SORT1 gene).
SNPs in the 9p21 and PHACTR1 gene loci were strongly associated with CAC and MI, and there are suggestive associations with both CAC and MI of SNPs in additional loci. Multiple genetic loci are associated with development of both underlying coronary atherosclerosis and clinical events.
PMCID: PMC3397173  PMID: 22144573
cardiac computed tomography; coronary artery calcification; coronary atherosclerosis; genome-wide association studies; myocardial infarction
22.  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.
PMCID: PMC3427729  PMID: 22504421
23.  Arterial stiffness, pressure and flow pulsatility and brain structure and function: the Age, Gene/Environment Susceptibility – Reykjavik Study 
Brain  2011;134(11):3398-3407.
Aortic stiffness increases with age and vascular risk factor exposure and is associated with increased risk for structural and functional abnormalities in the brain. High ambient flow and low impedance are thought to sensitize the cerebral microcirculation to harmful effects of excessive pressure and flow pulsatility. However, haemodynamic mechanisms contributing to structural brain lesions and cognitive impairment in the presence of high aortic stiffness remain unclear. We hypothesized that disproportionate stiffening of the proximal aorta as compared with the carotid arteries reduces wave reflection at this important interface and thereby facilitates transmission of excessive pulsatile energy into the cerebral microcirculation, leading to microvascular damage and impaired function. To assess this hypothesis, we evaluated carotid pressure and flow, carotid–femoral pulse wave velocity, brain magnetic resonance images and cognitive scores in participants in the community-based Age, Gene/Environment Susceptibility – Reykjavik study who had no history of stroke, transient ischaemic attack or dementia (n = 668, 378 females, 69–93 years of age). Aortic characteristic impedance was assessed in a random subset (n = 422) and the reflection coefficient at the aorta–carotid interface was computed. Carotid flow pulsatility index was negatively related to the aorta–carotid reflection coefficient (R = −0.66, P<0.001). Carotid pulse pressure, pulsatility index and carotid–femoral pulse wave velocity were each associated with increased risk for silent subcortical infarcts (hazard ratios of 1.62–1.71 per standard deviation, P<0.002). Carotid–femoral pulse wave velocity was associated with higher white matter hyperintensity volume (0.108 ± 0.045 SD/SD, P = 0.018). Pulsatility index was associated with lower whole brain (−0.127 ± 0.037 SD/SD, P<0.001), grey matter (−0.079 ± 0.038 SD/SD, P = 0.038) and white matter (−0.128 ± 0.039 SD/SD, P<0.001) volumes. Carotid–femoral pulse wave velocity (−0.095 ± 0.043 SD/SD, P = 0.028) and carotid pulse pressure (−0.114 ± 0.045 SD/SD, P = 0.013) were associated with lower memory scores. Pulsatility index was associated with lower memory scores (−0.165 ± 0.039 SD/SD, P<0.001), slower processing speed (−0.118 ± 0.033 SD/SD, P<0.001) and worse performance on tests assessing executive function (−0.155 ± 0.041 SD/SD, P<0.001). When magnetic resonance imaging measures (grey and white matter volumes, white matter hyperintensity volumes and prevalent subcortical infarcts) were included in cognitive models, haemodynamic associations were attenuated or no longer significant, consistent with the hypothesis that increased aortic stiffness and excessive flow pulsatility damage the microcirculation, leading to quantifiable tissue damage and reduced cognitive performance. Marked stiffening of the aorta is associated with reduced wave reflection at the interface between carotid and aorta, transmission of excessive flow pulsatility into the brain, microvascular structural brain damage and lower scores in various cognitive domains.
PMCID: PMC3212721  PMID: 22075523
haemodynamics; aortic stiffness; magnetic resonance imaging; brain structure; cognitive function
24.  Genome-wide association studies of cerebral white matter lesion burden: the CHARGE Consortium 
Annals of neurology  2011;69(6):928-939.
White matter hyperintensities (WMH) detectable by magnetic resonance imaging (MRI)are part of the spectrum of vascular injury associated with aging of the brain and are thought to reflect ischemic damage to the small deep cerebral vessels. WMH are associated with an increased risk of cognitive and motor dysfunction, dementia, depression, and stroke. Despite a significant heritability, few genetic loci influencing WMH burden have been identified.
We performed a meta-analysis of genome-wide association studies (GWAS) for WMH burden in 9,361 stroke-free individuals of European descent from 7 community-based cohorts. Significant findings were tested for replication in 3,024 individuals from 2 additional cohorts.
We identified 6 novel risk-associated single nucleotide polymorphisms (SNPs)in one locus on chromosome 17q25 encompassing 6 known genes including WBP2, TRIM65, TRIM47, MRPL38, FBF1, and ACOX1. The most significant association was for rs3744028 (Pdiscovery= 4.0×10−9; Preplication =1.3×10−7; Pcombined =4.0×10−15). Other SNPs in this region also reaching genome-wide significance are rs9894383 (P=5.3×10−9), rs11869977 (P=5.7×10−9), rs936393 (P=6.8×10−9), rs3744017 (P=7.3×10−9), and rs1055129 (P=4.1×10−8). Variant alleles at these loci conferred a small increase in WMH burden (4–8% of the overall mean WMH burden in the sample).
This large GWAS of WMH burden in community-based cohorts of individuals of European descent identifies a novel locus on chromosome 17. Further characterization of this locus may provide novel insights into the pathogenesis of cerebral WMH.
PMCID: PMC3122147  PMID: 21681796
25.  Distribution of Cortical Bone in the Femoral Neck and Hip Fracture: A Prospective Case-Control Analysis of 143 Incident Hip Fractures; the AGES-REYKJAVIK Study 
Bone  2011;48(6):1268-1276.
In this prospective nested case-control study we analyzed the circumferential differences in estimated cortical thickness (Est CTh) of the mid femoral neck as a risk factor for osteoporotic hip fractures in elderly women and men. Segmental QCT analysis of the mid femoral neck was applied to assess cortical thickness in anatomical quadrants. The superior region of the femoral neck was a stronger predictor for hip fracture than the inferior region, particularly in men. There were significant gender differences in Est CTh measurements in the control group but not in the case group. In multivariable analysis for risk of femoral neck (FN) fracture, Est CTh in the supero-anterior (SA) quadrant was significant in both women and men, and remained a significant predictor after adjustment for FN areal BMD (aBMD, dimensions g/cm2, DXA-like), (p=0.05 and p<0.0001, respectively). In conclusion, Est CTh in the SA quadrant best discriminated cases (n=143) from controls (n=298), especially in men. Cortical thinning superiorly in the hip might be of importance in determining resistance to fracture.
PMCID: PMC3129599  PMID: 21473947
cortical thickness; hip fracture; quantitative computed tomography; proximal femur; BMD

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