Bone mineral density and the risk of incident dementia: A meta-analysis.

BACKGROUND: It is not known whether bone mineral density (BMD) measured at baseline or as the rate of decline prior to baseline (prior bone loss) is a stronger predictor of incident dementia or Alzheimer's disease (AD). METHODS: We performed a meta-analysis of three longitudinal studies, the Framingham Heart Study (FHS), the Rotterdam Study (RS), and the Rush Memory and Aging Project (MAP), modeling the time to diagnosis of dementia as a function of BMD measures accounting for covariates. We included individuals with one or two BMD assessments, aged ≥60 years, and free of dementia at baseline with follow-up available. BMD was measured at the hip femoral neck using dual-energy X-ray absorptiometry (DXA), or at the heel calcaneus using quantitative ultrasound to calculate estimated BMD (eBMD). BMD at study baseline ("baseline BMD") and annualized percentage change in BMD prior to baseline ("prior bone loss") were included as continuous measures. The primary outcome was incident dementia diagnosis within 10 years of baseline, and incident AD was a secondary outcome. Baseline covariates included age, sex, body mass index, ApoE4 genotype, and education. RESULTS: The combined sample size across all three studies was 4431 with 606 incident dementia diagnoses, 498 of which were AD. A meta-analysis of baseline BMD across three studies showed higher BMD to have a significant protective association with incident dementia with a hazard ratio of 0.47 (95% CI: 0.23-0.96; p = 0.038) per increase in g/cm2 , or 0.91 (95% CI: 0.84-0.995) per standard deviation increase. We observed a significant association between prior bone loss and incident dementia with a hazard ratio of 1.30 (95% CI: 1.12-1.51; p < 0.001) per percent increase in prior bone loss only in the FHS cohort. CONCLUSIONS: Baseline BMD but not prior bone loss was associated with incident dementia in a meta-analysis across three studies.

Metabolomic profiles predict individual multidisease outcomes.

Risk stratification is critical for the early identification of high-risk individuals and disease prevention. Here we explored the potential of nuclear magnetic resonance (NMR) spectroscopy-derived metabolomic profiles to inform on multidisease risk beyond conventional clinical predictors for the onset of 24 common conditions, including metabolic, vascular, respiratory, musculoskeletal and neurological diseases and cancers. Specifically, we trained a neural network to learn disease-specific metabolomic states from 168 circulating metabolic markers measured in 117,981 participants with ~1.4 million person-years of follow-up from the UK Biobank and validated the model in four independent cohorts. We found metabolomic states to be associated with incident event rates in all the investigated conditions, except breast cancer. For 10-year outcome prediction for 15 endpoints, with and without established metabolic contribution, a combination of age and sex and the metabolomic state equaled or outperformed established predictors. Moreover, metabolomic state added predictive information over comprehensive clinical variables for eight common diseases, including type 2 diabetes, dementia and heart failure. Decision curve analyses showed that predictive improvements translated into clinical utility for a wide range of potential decision thresholds. Taken together, our study demonstrates both the potential and limitations of NMR-derived metabolomic profiles as a multidisease assay to inform on the risk of many common diseases simultaneously.

The longitudinal association of sleep and 24-hour activity rhythms with cortisol response to a very low dose of dexamethasone.

OBJECTIVES: Poor sleep is common in the general population, with hyperarousal and stress often suggested as causal factors. Conversely, sleep might also affect the stress response, in which the hypothalamic-pituitary-adrenal (HPA) axis plays a key role. We assessed the longitudinal association of sleep and 24-hour activity rhythms with functioning of the negative feedback loop of the HPA axis, as indicated by the cortisol response to a very low dose of dexamethasone. DESIGN: Longitudinal cohort. SETTING: Population-based. PARTICIPANTS: This study included 410 participants (mean age: 56.1 ± 5.5 years, 59% women) from the Rotterdam Study. For 217 participants, the cortisol response to dexamethasone was assessed again after a median follow-up of 5.7 years (IQR = 5.5-5.8). MEASUREMENTS: Between 2004 and 2007, sleep and 24-hour activity rhythms were estimated with actigraphy (mean duration: 146 ± 19.6 hours) and sleep quality with the Pittsburgh Sleep Quality Index. To assess the negative feedback loop of the HPA axis we measured cortisol before and after the intake of a very low-dose of dexamethasone (0.25 mg). RESULTS: Unstable (B = 1.64, 95% CI = 0.78; 2.50) and fragmented (B = -1.31, 95% CI = -2.17; -0.45) 24-hour activity rhythms, and a poor self-rated sleep quality (B = -0.02, 95% CI = -0.04; 0.00) were associated with an enhanced cortisol response to dexamethasone over time, also in those without clinically relevant depressive symptoms and those not using psychoactive medication. CONCLUSIONS: This study demonstrates a longitudinal association of disturbed 24-hour activity rhythms and poor self-rated sleep quality with an enhanced cortisol response to dexamethasone, in other words stronger suppression of cortisol. STATEMENT OF SIGNIFICANCE: This study shows that disturbed 24-hour activity rhythms and a poor self-rated sleep quality are associated with functioning of the negative feedback loop over a period of years.

Trends in Staging, Treatment, and Survival in Colorectal Cancer Between 1990 and 2014 in the Rotterdam Study.

BACKGROUND: This study aims to assess trends in patient-related factors and treatment strategies in Dutch colorectal cancer (CRC) patients and their effect on survival. METHODS: Data were obtained from the Rotterdam study, an ongoing population-based study of individuals aged ≥45 years. Between 1990 and 2014, incident, pathology-confirmed CRC cases were divided into two groups based on date of diagnosis (either before or after January 1, 2003). Patient characteristics, initial treatment, and date of mortality were collected. Analyses were performed using Kaplan-Meier and Cox proportional hazard models. RESULTS: Of 14,928 individuals, 272 developed colon cancer and 124 rectal cancer. Median follow-up was 13.2 years. Patients diagnosed after January 1, 2003 were treated chemotherapeutically more often than those diagnosed prior to this date in colon cancer (28.6% vs. 9.1%, p = 0.02) and treated more often with chemotherapy (38.6% vs. 12.3%, p = 0.02) and radiotherapy (41.3% vs. 10.2%, p = 0.001) in rectal cancer. Overall survival, adjusted for patient, tumor characteristics, and treatment, improved in rectal cancer (HR, 0.31; 95% CI, 0.13-0.74) but remained stable in colon cancer (HR, 1.28; 95% CI, 0.84-1.95). CONCLUSION: Chemotherapeutic agents and radiotherapy are increasingly used in CRC patients. Survival in rectal cancer improved, whereas in colon cancer this was not observed.

A systematic review and participant-level meta-analysis found little association of retinal microvascular caliber with reduced kidney function.

Previously, variation in retinal vascular caliber has been reported in association with chronic kidney disease (CKD) but findings remain inconsistent. To help clarify this we conducted individual participant data meta-analysis and aggregate data meta-analysis on summary estimates to evaluate cross-sectional associations between retinal vascular caliber and CKD. A systematic review was performed using Medline and EMBASE for articles published until October 2018. The aggregate analysis used a two-stage approach combining summary estimates from eleven studies (44,803 patients) while the individual participant analysis used a one-stage approach combining raw data from nine studies (33,222 patients). CKD stages 3-5 was defined as an estimated glomerular filtration rate under 60 mL/min/1.73m2. Retinal arteriolar and venular caliber (central retinal arteriolar and venular equivalent) were assessed from retinal photographs using computer-assisted methods. Logistic regression estimated relative risk of CKD stages 3-5 associated with a 20 µm decrease (approximately one standard deviation) in central retinal arteriolar and venular equivalent. Prevalence of CKD stages 3-5 was 11.2% of 33,222 and 11.3% of 44,803 patients in the individual participant and aggregate data analysis, respectively. No significant associations were detected in adjusted analyses between central retinal arteriolar and venular equivalent and CKD stages 3-5 in the aggregate analysis for central retinal arteriolar relative risk (0.98, 95% confidence interval 0.94-1.03); venular equivalent (0.99, 0.95-1.04) or individual participant central retinal arteriolar (0.99, 0.95-1.04) or venular equivalent (1.01, 0.97-1.05). Thus, meta-analysis provided little evidence to suggest that cross sectional direct measurements of retinal vascular caliber was associated with CKD stages 3-5 in the general population. Hence, meta-analyses of longitudinal studies evaluating the association between retinal parameters and CKD stages 3-5 may be warranted.

Quantitative Gait Impairments in Patients With Stroke or Transient Ischemic Attack: A Population-Based Approach.

BACKGROUND AND PURPOSE: Gait is a complex process involving various cortical and subcortical brain regions. An acute stroke or transient ischemic attack (TIA) may disrupt white and gray matter integrity and, therefore, affect gait in patients without evident neurological signs. We determined whether patients with stroke and TIA experience subtle changes in global gait and several independent gait domains. METHODS: In the population-based Rotterdam Study, 4456 participants (median age, 65 years; 55% women) underwent detailed quantitative gait assessment (GAITRite) between 2009 and 2016. We summarized 30 gait parameters into a global gait score and 7 mutually independent gait domains. First, we assessed the association between prior stroke or TIA and global and domain-specific gait using linear regression models adjusted for age, sex, vascular risk factors, and cognition. Subsequently, we repeated the analysis stratified by the presence of different neurological symptoms in a subgroup of participants with ischemic stroke after study entry. RESULTS: Compared with participants without prior stroke, patients with stroke had a worse global gait (SD, -0.49 [95% CI, -0.64 to -0.34]), especially in the gait domains Pace, Phases, and Turning. The detrimental effect of stroke on gait was amplified in participants with worse cognition. No gait differences were found between participants with and without prior TIA. Ischemic stroke patients without lower limb weakness, loss of coordination, or visuospatial problems still had a worse gait compared with participants without stroke. Stratification by different stroke symptoms showed that different gait domains were affected in each group. CONCLUSIONS: Prior stroke without neurological signs that affect gait is still associated with gait difficulties compared with individuals without stroke. Our study suggests that stroke not only has a direct impact on gait through neurological impairments but also includes an indirect effect possibly through disruption of gray and white matter integrity and accelerated neurodegeneration.

The cardiovascular risk profile of middle age women previously diagnosed with premature ovarian insufficiency: A case-control study.

BACKGROUND: Cardiovascular disease (CVD) is the leading cause of death in women worldwide. The cardiovascular risk profile deteriorates after women enter menopause. By definition, women diagnosed with premature ovarian insufficiency (POI) experience menopause before 40 years of age, which may render these women even more susceptible to develop CVD later in life. However, prospective long-term follow up data of well phenotyped women with POI are scarce. In the current study we compare the CVD profile and risk of middle aged women previously diagnosed with POI, to a population based reference group matched for age and BMI. METHODS AND FINDINGS: We compared 123 women (age 49.0 (± 4.3) years) and diagnosed with POI 8.1 (IQR: 6.8-9.6) years earlier, with 123 population controls (age 49.4 (± 3.9) years). All women underwent an extensive standardized cardiovascular screening. We assessed CVD risk factors including waist circumference, BMI, blood pressure, lipid profile, pulse wave velocity (PWV), and the prevalence of diabetes mellitus, metabolic syndrome (MetS) and carotid intima media thickness (cIMT), in both women with POI and controls. We calculated the 10-year CVD Framingham Risk Score (FRS) and the American Heart Association's suggested cardiovascular health score (CHS). Waist circumference (90.0 (IQR: 83.0-98.0) versus 80.7 (IQR: 75.1-86.8), p < 0.01), waist-to-hip ratio (0.90 (IQR: 0.85-0.93) versus 0.79 (IQR: 0.75-0.83), p < 0.01), systolic blood pressure (124 (IQR 112-135) versus 120 (IQR109-131), p < 0.04) and diastolic blood pressure (81 (IQR: 76-89) versus 78 (IQR: 71-86), p < 0.01), prevalence of hypertension (45 (37%) versus 21 (17%), p < 0.01) and MetS (19 (16%) versus 4 (3%), p < 0.01) were all significantly increased in women with POI compared to healthy controls. Other risk factors, however, such as lipids, glucose levels and prevalence of diabetes were similar comparing women with POI versus controls. The arterial stiffness assessed by PWV was also similar in both populations (8.1 (IQR: 7.1-9.4) versus 7.9 (IQR: 7.1-8.4), p = 0.21). In addition, cIMT was lower in women with POI compared to controls (550 µm (500-615) versus 684 µm (618-737), p < 0.01). The calculated 10-year CVD risk was 5.9% (IQR: 3.7-10.6) versus 6.0% (IQR: 3.9-9.0) (p = 0.31) and current CHS was 6.1 (1.9) versus 6.5 (1.6) (p = 0.07), respectively in POI versus controls. CONCLUSIONS: Middle age women with POI presented with more unfavorable cardiovascular risk factors (increased waist circumference and a higher prevalence of hypertension and MetS) compared to age and BMI matched population controls. In contrast, the current study reveals a lower cIMT and similar 10-year cardiovascular disease risk and cardiovascular health score. In summary, neither signs of premature atherosclerosis nor a worse cardiovascular disease risk or health score were observed among middle age women with POI compared to population controls. Longer-term follow-up studies of women of more advanced age are warranted to establish whether women with POI are truly at increased risk of developing CVD events later in life. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02616510.

Survival After Uncomplicated EVAR in Octogenarians is Similar to the General Population of Octogenarians Without an Abdominal Aortic Aneurysm.

OBJECTIVE: Long term survival after endovascular aortic aneurysm repair (EVAR) in octogenarians remains unclear. This was evaluated by comparing octogenarians after EVAR with a matched group of octogenarians without an abdominal aortic aneurysm (AAA) from the Rotterdam Study (RS). The influence of complications after EVAR on survival was also studied with the aim of identifying risk factors for the development of complications in octogenarians. METHODS: Using propensity score matching (PSM), 83 EVAR octogenarians were matched for comorbidities with 83 octogenarians from the RS, and survival was compared between these two groups using Cox proportional hazard analysis. Then, complications were studied, defined as cardiac or pulmonary, renal deterioration, access site bleeding, acute limb ischaemia or bowel ischaemia, within 30 days of surgery between 83 EVAR octogenarians and 475 EVAR non-octogenarians. Also, the difference in baseline characteristics between the octogenarians with and without complications after EVAR were studied, and survival was compared between the RS controls and the complicated and uncomplicated EVAR octogenarians separately. RESULTS: The total EVAR octogenarian population did not show an increased mortality risk compared with RS octogenarian controls (hazard ratio [HR] 1.28, 95% confidence interval [CI] 0.84-1.97). Post-operative complications occurred in 22 octogenarians (27%) and 59 non-octogenarians (12.4%, p < .001), mainly cardiac, pulmonary, and bleeding complications. All baseline characteristics were similar in the complicated EVAR octogenarians compared with the uncomplicated EVAR octogenarians. After uncomplicated EVAR, octogenarians had a similar survival compared with the RS controls (HR 1.09, 95% CI 0.68-1.77), but after complicated EVAR their mortality risk increased significantly (HR 1.93, 95% CI 1.06-3.54). CONCLUSION: After standard EVAR, the life expectancy of octogenarians is the same as that of a matched group from the general population without an AAA, provided they do not develop early post-operative complications. Patient selection and meticulous peri-operative care are key.

Diet quality and chronic axonal polyneuropathy: a population-based study.

OBJECTIVE: To investigate the association between diet quality and chronic axonal polyneuropathy. METHODS: Between June 2013 and January 2017, among 1650 participants of the Rotterdam Study (median age 69.1 years, 54.2% women), diet quality was quantified based on food frequency questionnaires as a sum score of adherence (yes/no) to 14 components of the Dutch dietary guidelines. Presence of polyneuropathy was determined based on a questionnaire, neurological examination of the legs, and nerve conduction studies. We used logistic regression to associate diet quality with the presence of chronic axonal polyneuropathy and linear regression to associate with sural sensory nerve action potential (SNAP) amplitude in participants without polyneuropathy. Results were adjusted for age, sex, time between measurements, body mass index, blood pressure, diabetes mellitus, smoking, kidney function, and education. RESULTS: Overall diet quality was not associated with chronic axonal polyneuropathy (odds ratio [OR] = 0.99, 95% confidence interval [CI] 0.88; 1.12, P = 0.842), nor with sural SNAP amplitude in participants without polyneuropathy (difference = 0.01, 95% CI -0.14; 0.15, P = 0.993). Although not surviving multiple testing, a nominally significant association was found between salt intake ≤6 g/day and presence of chronic axonal polyneuropathy (OR = 0.55, 95% CI 0.35; 0.86, P = 0.008). INTERPRETATION: We did not find an association between diet quality and chronic axonal polyneuropathy.

Potential Interplay between Dietary Saturated Fats and Genetic Variants of the NLRP3 Inflammasome to Modulate Insulin Resistance and Diabetes Risk: Insights from a Meta-Analysis of 19 005 Individuals.

SCOPE: Insulin resistance (IR) and inflammation are hallmarks of type 2 diabetes (T2D). The nod-like receptor pyrin domain containing-3 (NLRP3) inflammasome is a metabolic sensor activated by saturated fatty acids (SFA) initiating IL-1ß inflammation and IR. Interactions between SFA intake and NLRP3-related genetic variants may alter T2D risk factors. METHODS: Meta-analyses of six Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium (n = 19 005) tested interactions between SFA and NLRP3-related single-nucleotide polymorphisms (SNPs) and modulation of fasting insulin, fasting glucose, and homeostasis model assessment of insulin resistance. RESULTS: SFA interacted with rs12143966, wherein each 1% increase in SFA intake increased insulin by 0.0063 IU mL-1 (SE ± 0.002, p = 0.001) per each major (G) allele copy. rs4925663, interacted with SFA (ß ± SE = -0.0058 ± 0.002, p = 0.004) to increase insulin by 0.0058 IU mL-1 , per additional copy of the major (C) allele. Both associations are close to the significance threshold (p < 0.0001). rs4925663 causes a missense mutation affecting NLRP3 expression. CONCLUSION: Two NLRP3-related SNPs showed potential interaction with SFA to modulate fasting insulin. Greater dietary SFA intake accentuates T2D risk, which, subject to functional validation, may be further elaborated depending on NLRP3-related genetic variants.

Genome-wide association analyses of risk tolerance and risky behaviors in over 1 million individuals identify hundreds of loci and shared genetic influences.

Humans vary substantially in their willingness to take risks. In a combined sample of over 1 million individuals, we conducted genome-wide association studies (GWAS) of general risk tolerance, adventurousness, and risky behaviors in the driving, drinking, smoking, and sexual domains. Across all GWAS, we identified hundreds of associated loci, including 99 loci associated with general risk tolerance. We report evidence of substantial shared genetic influences across risk tolerance and the risky behaviors: 46 of the 99 general risk tolerance loci contain a lead SNP for at least one of our other GWAS, and general risk tolerance is genetically correlated ([Formula: see text] ~ 0.25 to 0.50) with a range of risky behaviors. Bioinformatics analyses imply that genes near SNPs associated with general risk tolerance are highly expressed in brain tissues and point to a role for glutamatergic and GABAergic neurotransmission. We found no evidence of enrichment for genes previously hypothesized to relate to risk tolerance.

Impact of cumulative SBP and serious adverse events on efficacy of intensive blood pressure treatment: a randomized clinical trial.

BACKGROUND: Intensive blood pressure lowering is increasingly gaining attention. In addition to higher baseline blood pressure, cumulative SBP, visit-to-visit variability, and treatment-induced serious adverse events (SAEs) could impact treatment efficacy over time. Our aim was to assess the impact of cumulative SBP and SAEs on intensive hypertension treatment efficacy in the Systolic Blood Pressure Intervention Trial (SPRINT) population during follow-up. METHODS: Secondary analysis of the SPRINT study: a randomized, controlled, open-label trial including 102 clinical sites in the United States. We included 9068 SPRINT participants with 128 139 repeated SBP measurements. Participants were randomly assigned to intensive (target SBP < 120 mmHg) versus standard treatment (target SBP between 135 and 139 mmHg). We used cumulative joint models for longitudinal and survival data analysis. Primary outcome was a composite outcome of myocardial infarction, other acute coronary syndromes, acute decompensated heart failure, stroke, and cardiovascular mortality. RESULTS: Although intensive treatment decreased the risk for the primary SPRINT outcome at the start of follow-up, its effect lost significance after 3.4 years of follow-up in the total SPRINT population and after 1.3, 1.3, 1.1, 1.8, 2.1, 1.8, and 3.4 years among participants with prevalent chronic kidney disease, prevalent cardiovascular disease, women, black individuals, participants less than 75 years, those with baseline SBP more than 132 mmHg, and individuals who suffered SAEs during follow-up, respectively. CONCLUSION: The initial beneficial impact of intensive hypertension treatment might be offset by cumulative SBP and development of SAEs during follow-up.

Thinner retinal layers are associated with changes in the visual pathway: A population-based study.

Increasing evidence shows that thinner retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL), assessed on optical coherence tomography (OCT), are reflecting global brain atrophy. Yet, little is known on the relation of these layers with specific brain regions. Using voxel-based analysis, we aimed to unravel specific brain regions associated with these retinal layers. We included 2,235 persons (mean age: 67.3 years, 55% women) from the Rotterdam Study (2007-2012) who had gradable retinal OCT images and brain magnetic resonance imaging (MRI) scans, including diffusion tensor (DT) imaging. Thicknesses of peripapillary RNFL and perimacular GCL were measured using an automated segmentation algorithm. Voxel-based morphometry protocols were applied to process DT-MRI data. We investigated the association between retinal layer thickness with voxel-wise gray matter density and white matter microstructure by performing linear regression models. We found that thinner RNFL and GCL were associated with lower gray matter density in the visual cortex, and with lower fractional anisotropy and higher mean diffusivity in white matter tracts that are part of the optic radiation. Furthermore, thinner GCL was associated with lower gray matter density of the thalamus. Thinner RNFL and GCL are associated with gray and white matter changes in the visual pathway suggesting that retinal thinning on OCT may be specifically associated with changes in the visual pathway rather than with changes in the global brain. These findings may serve as a basis for understanding visual symptoms in elderly patients, patients with Alzheimer's disease, or patients with posterior cortical atrophy.

Brain Volumes and Longitudinal Cognitive Change: A Population-based Study.

OBJECTIVE: To investigate the association of brain volumes, white matter lesion (WML) volumes, and lacunes, with cognitive decline in a population-based cohort of nondemented persons. METHODS: Within the Rotterdam Study, 3624 participants underwent brain magnetic resonance imaging. Cognition was evaluated at baseline (2005 to 2009) and at the follow-up visit (2011 to 2013). We used a test battery that tapped into domains of executive function, information processing speed, motor speed, and memory. The volumetric measures assessed were total brain volume, lobar (gray matter and white matter) volumes, and hippocampal volumes. We also studied the association of WML volumes and lacunes with cognitive decline using linear regression models. RESULTS: Total brain volume was associated with decline in global cognition, information processing, and motor speed (P<0.001) in analyses controlled for demographic and vascular factors. Specifically, smaller frontal and parietal lobes were associated with decline in information processing and motor speed, and smaller temporal and parietal lobes were associated with decline in general cognition and motor speed (P<0.001 for all tests). Total WML volume was associated with decline in executive function. Lobar WML volume, hippocampal volume, and lacunes were not associated with cognitive decline. CONCLUSIONS: Lower brain volume is associated with subsequent cognitive decline. Although lower total brain volume was significantly associated with decline in global cognition, specific lobar volumes were associated with decline in certain cognitive domains.

Maximizing the Potential of Longitudinal Cohorts for Research in Neurodegenerative Diseases: A Community Perspective.

Despite a wealth of activity across the globe in the area of longitudinal population cohorts, surprisingly little information is available on the natural biomedical history of a number of age-related neurodegenerative diseases (ND), and the scope for intervention studies based on these cohorts is only just beginning to be explored. The Joint Programming Initiative on Neurodegenerative Disease Research (JPND) recently developed a novel funding mechanism to rapidly mobilize scientists to address these issues from a broad, international community perspective. Ten expert Working Groups, bringing together a diverse range of community members and covering a wide ND landscape [Alzheimer's, Parkinson's, frontotemporal degeneration, amyotrophic lateral sclerosis (ALS), Lewy-body and vascular dementia] were formed to discuss and propose potential approaches to better exploiting and coordinating cohort studies. The purpose of this work is to highlight the novel funding process along with a broad overview of the guidelines and recommendations generated by the ten groups, which include investigations into multiple methodologies such as cognition/functional assessment, biomarkers and biobanking, imaging, health and social outcomes, and pre-symptomatic ND. All of these were published in reports that are now publicly available online.

Fine-mapping the effects of Alzheimer's disease risk loci on brain morphology.

The neural substrate of genetic risk variants for Alzheimer's disease (AD) remains unknown. We studied their effect on healthy brain morphology to provide insight into disease etiology in the preclinical phase. We included 4071 nondemented, elderly participants of the population-based Rotterdam Study who underwent brain magnetic resonance imaging and genotyping. We performed voxel-based morphometry (VBM) on all gray-matter voxels for 19 previously identified, common AD risk variants. Whole-brain expression data from the Allen Human Brain Atlas was used to examine spatial overlap between VBM association results and expression of genes in AD risk loci regions. Brain regions most significantly associated with AD risk variants were the left postcentral gyrus with ABCA7 (rs4147929, p = 4.45 × 10-6), right superior frontal gyrus by ZCWPW1 (rs1476679, p = 5.12 × 10-6), and right postcentral gyrus by APOE (p = 6.91 × 10-6). Although no individual voxel passed multiple-testing correction, we found significant spatial overlap between the effects of AD risk loci on VBM and the expression of genes (MEF2C, CLU, and SLC24A4) in the Allen Brain Atlas. Results are available online on www.imagene.nl/ADSNPs/. In this single largest imaging genetics data set worldwide, we found that AD risk loci affect cortical gray matter in several brain regions known to be involved in AD, as well as regions that have not been implicated before.

Common variation in COL4A1/COL4A2 is associated with sporadic cerebral small vessel disease.

OBJECTIVES: We hypothesized that common variants in the collagen genes COL4A1/COL4A2 are associated with sporadic forms of cerebral small vessel disease. METHODS: We conducted meta-analyses of existing genotype data among individuals of European ancestry to determine associations of 1,070 common single nucleotide polymorphisms (SNPs) in the COL4A1/COL4A2 genomic region with the following: intracerebral hemorrhage and its subtypes (deep, lobar) (1,545 cases, 1,485 controls); ischemic stroke and its subtypes (cardioembolic, large vessel disease, lacunar) (12,389 cases, 62,004 controls); and white matter hyperintensities (2,733 individuals with ischemic stroke and 9,361 from population-based cohorts with brain MRI data). We calculated a statistical significance threshold that accounted for multiple testing and linkage disequilibrium between SNPs (p < 0.000084). RESULTS: Three intronic SNPs in COL4A2 were significantly associated with deep intracerebral hemorrhage (lead SNP odds ratio [OR] 1.29, 95% confidence interval [CI] 1.14-1.46, p = 0.00003; r(2) > 0.9 between SNPs). Although SNPs associated with deep intracerebral hemorrhage did not reach our significance threshold for association with lacunar ischemic stroke (lead SNP OR 1.10, 95% CI 1.03-1.18, p = 0.0073), and with white matter hyperintensity volume in symptomatic ischemic stroke patients (lead SNP OR 1.07, 95% CI 1.01-1.13, p = 0.016), the direction of association was the same. There was no convincing evidence of association with white matter hyperintensities in population-based studies or with non-small vessel disease cerebrovascular phenotypes. CONCLUSIONS: Our results indicate an association between common variation in the COL4A2 gene and symptomatic small vessel disease, particularly deep intracerebral hemorrhage. These findings merit replication studies, including in ethnic groups of non-European ancestry.

The role of cerebellar volume in cognition in the general elderly population.

BACKGROUND: It is unknown whether the cerebellum affects cognitive function in an aging community-dwelling population. In a population-based study on 3745 nondemented individuals aged 45 years and above, we investigated the relationship between cerebellar volume and cognitive function. METHODS: Brain volumes were obtained using automatic tissue segmentation of magnetic resonance imaging scans. Cognitive functioning was assessed using MMSE and cognitive compound scores of global cognition, executive function, information processing speed, memory, and motor speed. Linear regression modeling was used to study the associations between cerebellar volumes and cognitive measures, independent of cerebral volumes. RESULTS: We found a relationship between larger cerebellar volume and better global cognition, executive function, information processing speed, and motor speed. After adjustment for cerebral volume, only cerebellar gray matter volume remained borderline significantly associated with global cognition and information processing speed. After Bonferroni correction, the few associations found between cerebellar volume and cognition disappeared. CONCLUSIONS: We only found a minor relationship between larger cerebellar volume and better cognition in healthy older adults, which further attenuated after correcting for cerebral volume. Our findings support the notion that cerebellar volume has an influence on cognition in aging, but that it is not the major leading structure.

Genome-wide association study for circulating tissue plasminogen activator levels and functional follow-up implicates endothelial STXBP5 and STX2.

OBJECTIVE: Tissue plasminogen activator (tPA), a serine protease, catalyzes the conversion of plasminogen to plasmin, the major enzyme responsible for endogenous fibrinolysis. In some populations, elevated plasma levels of tPA have been associated with myocardial infarction and other cardiovascular diseases. We conducted a meta-analysis of genome-wide association studies to identify novel correlates of circulating levels of tPA. APPROACH AND RESULTS: Fourteen cohort studies with tPA measures (N=26 929) contributed to the meta-analysis. Three loci were significantly associated with circulating tPA levels (P<5.0×10(-8)). The first locus is on 6q24.3, with the lead single nucleotide polymorphism (SNP; rs9399599; P=2.9×10(-14)) within STXBP5. The second locus is on 8p11.21. The lead SNP (rs3136739; P=1.3×10(-9)) is intronic to POLB and <200 kb away from the tPA encoding the gene PLAT. We identified a nonsynonymous SNP (rs2020921) in modest linkage disequilibrium with rs3136739 (r(2)=0.50) within exon 5 of PLAT (P=2.0×10(-8)). The third locus is on 12q24.33, with the lead SNP (rs7301826; P=1.0×10(-9)) within intron 7 of STX2. We further found evidence for the association of lead SNPs in STXBP5 and STX2 with expression levels of the respective transcripts. In in vitro cell studies, silencing STXBP5 decreased the release of tPA from vascular endothelial cells, whereas silencing STX2 increased the tPA release. Through an in silico lookup, we found no associations of the 3 lead SNPs with coronary artery disease or stroke. CONCLUSIONS: We identified 3 loci associated with circulating tPA levels, the PLAT region, STXBP5, and STX2. Our functional studies implicate a novel role for STXBP5 and STX2 in regulating tPA release.