Interplay of circulating leptin and obesity in cognition and cerebral volumes in older adults

We aimed to investigate whether circulating leptin and body mass index (BMI) associate independently with cognitive function (decline) and brain volumes using magnetic resonance imaging (MRI) in older individuals at risk of cardiovascular disease. We studied the cross-sectional and longitudinal associations in participants enrolled in the PROSPER study (Prospective Study of Pravastatin in the Elderly at Risk). Cognitive function was tested at baseline and repeated during a mean follow-up time of 3.2 years. Analyses were performed with multivariable (repeated) linear regression models and adjusted for demographics, cardiovascular risk-factors, and stratified by sex. We included 5623 dementia-free participants (52 % female, mean age 75 years) with a mean BMI of 26.9 (SD = 4.1). In a sub-study, 527 participants underwent brain MRI. At baseline, individuals with a BMI > 30 had a worse performance on the Stroop test (β 5.0 s, 95 %CI 2.6;7.5) and larger volumes of the amygdala (β 234 mm³, 95 %CI 3;464) and hippocampus (β 590 mm³, 95 %CI 181;999), independent of intracranial volume and serum leptin levels, compared with individuals with the reference BMI (BMI 18-25 kg/m²). Per log ng/mL higher serum leptin, independent of BMI, a 135 mm³ (95 %CI 2;268) higher volume of the amygdala was found, but no association was observed with cognitive tests nor with other brain volumes. Stratification for sex did not materially change the results. Whereas higher BMI associated with worse cognitive function independent of leptin levels, our study provided evidence that leptin and BMI independently associate with amygdala volume suggesting potential distinct biological associations.

Basal cell carcinoma genetic susceptibility increases the rate of skin ageing: a Mendelian randomization study

BACKGROUND

Onset of basal cell carcinoma (BCC) is connected to skin ageing, but it is unclear whether higher BCC genetic susceptibility drives skin ageing.

OBJECTIVES

To investigate whether loci increasing genetic susceptibility to BCC also drive multiple features of skin ageing, independently of confounding factors, using Mendelian randomization.

METHODS

A Mendelian randomization study was conducted in older adults from the Leiden Longevity Study (N = 604). A total of 25 BCC loci, selected based on a published genome-wide association study on BCC (P-value < 5 × 10^-8 ), were used as genetic instruments for the calculation of a standardized (mean = 0, SD = 1) weighted BCC genetic risk score. Based on facial photographs, we determined perceived age, and skin wrinkling and pigmented spot grading.

RESULTS

A higher BCC genetic risk score was associated with a higher perceived age (adjusted for chronological age and sex) of 0.88 years (95% CI: 0.44, 1.31; P-value = 7.1e^-5 ), greater wrinkling by 0.14 grades (95% CI: 0.05, 0.23; P-value = 2.3e^-3 ), and greater pigmented spots by 0.17 grades (95% CI: 0.08, 0.25; P-value = 1.1e^-4 ). These findings were weakened but still present after exclusion of gene variants in MC1R and IRF4 which have potential pleiotropic effects.

CONCLUSIONS

Mechanisms influenced by genetic loci increasing susceptibility to BCC also drive skin ageing suggesting shared biology and shared targets for interventions.

High-sensitivity C-reactive protein, low-grade systemic inflammation and type 2 diabetes mellitus: A two-sample Mendelian randomization study

BACKGROUND AND AIMS

The role of inflammation in type 2 diabetes mellitus (T2D) remains unclear. We investigated the associations of high sensitivity C-reactive protein (hsCRP) concentration with T2D and glycemic traits using two-sample Mendelian Randomization.

METHODS AND RESULTS

We used publically available summary-statistics data from genome-wide association studies on T2D (DIAGRAM: 12 171 cases; 56 862 controls) and glycemic traits (MAGIC: 46 186 participants without diabetes mellitus). We combined the effects of the genetic instrumental variables through inverse-variance weighting (IVW), and MR-Egger regression and weighted-median estimation as sensitivity analyses which take into account potential violations (e.g., directional pleiotropy) of the assumptions of instrumental variable analyses. Analyses were conducted using 15 known hsCRP genetic instruments among which 6 instruments are hsCRP specific and not involved in inflammatory processes beyond hsCRP concentration regulation. Though we found no association between the combined effect of the genetic instrumental variables for hsCRP and T2D with IVW (odds ratio per 1 ln [hsCRP in mg/L]: 1.15; 95% confidence interval: 0.93, 1.42), we found associations for T2D with MR-Egger regression and weighted-median estimation (odds ratio with 95% confidence interval per 1 ln [hsCRP in mg/L], MR-Egger regression: 1.29; 1.08, 1.49; weighted-median estimator: 1.21; 1.02, 1.39). We found no association with T2D for the combination of hsCRP-specific genetic instruments nor did we found associations with glycemic traits in any of the analyses.

CONCLUSION

Evidence was provided for a potential causal association between hsCRP and T2D, but only after considering directional pleiotropy. However, hsCRP was not causally associated with glycemic traits.

Pharmacogenomics study of thiazide diuretics and QT interval in multi-ethnic populations: the cohorts for heart and aging research in genomic epidemiology

Thiazide diuretics, commonly used antihypertensives, may cause QT interval (QT) prolongation, a risk factor for highly fatal and difficult to predict ventricular arrhythmias. We examined whether common single-nucleotide polymorphisms (SNPs) modified the association between thiazide use and QT or its component parts (QRS interval, JT interval) by performing ancestry-specific, trans-ethnic and cross-phenotype genome-wide analyses of European (66%), African American (15%) and Hispanic (19%) populations (N=78 199), leveraging longitudinal data, incorporating corrected standard errors to account for underestimation of interaction estimate variances and evaluating evidence for pathway enrichment. Although no loci achieved genome-wide significance (P<5 × 10-8), we found suggestive evidence (P<5 × 10-6) for SNPs modifying the thiazide-QT association at 22 loci, including ion transport loci (for example, NELL1, KCNQ3). The biologic plausibility of our suggestive results and simulations demonstrating modest power to detect interaction effects at genome-wide significant levels indicate that larger studies and innovative statistical methods are warranted in future efforts evaluating thiazide-SNP interactions.

A critical appraisal of pharmacogenetic inference

In essence, pharmacogenetic research is aimed at discovering variants of importance to gene-treatment interaction. However, epidemiological studies are rarely set up with this goal in mind. It is therefore of great importance that researchers clearly communicate which assumptions they have had to make, and which inherent limitations apply to the interpretation of their results. This review discusses considerations of, and the underlying assumptions for, utilizing different response phenotypes and study designs popular in pharmacogenetic research to infer gene-treatment interaction effects, with a special focus on those dealing with of clinical effects of drug treatment.

Interrelationship of the rs7903146 TCF7L2 gene variant with measures of glucose metabolism and adiposity: The NEO study

BACKGROUND AND AIMS

We investigated the interrelationship of rs7903146-T in TCF7L2 with measures of glucose metabolism and measures of adiposity.

METHODS AND RESULTS

This cross-sectional analysis was conducted in 5744 middle-aged participants (mean (standard deviation [SD]) age is 55.9 (6.0) years) from the Netherlands Epidemiology of Obesity (NEO) Study. Associations between rs7903146-T and Type 2 diabetes mellitus (T2D) were assessed with logistic regression. Additive (per-allele) associations with measures of glucose metabolism (e.g., fasting insulin) and adiposity (e.g., body mass index [BMI]) were examined with multivariable linear regression. In the total study population, rs7903146-T was associated with a higher risk of T2D (additive odds ratio: 1.42; 95% confidence interval: 1.17; 1.72), and specifically with T2D treated with insulin analogs (2.31 [1.19; 4.46]). After exclusion of participants treated with glucose-lowering medication, rs7903146-T was associated with lower mean insulin concentration (additive mean difference: -0.07 SD [-0.14; 0.00]), but not with higher mean glucose concentration (0.03 SD [-0.01; 0.07]). Furthermore, rs7903146-T was associated with, among other measures of adiposity, a lower mean BMI (-0.04 SD [-0.09; -0.00]), and a lower mean total body fat (-0.04 SD [-0.08; -0.00]). The association between rs7903146-T and T2D increased after adjustment for BMI (odds ratio: 1.51 [1.24; 1.86]); the association between rs7903146-T and fasting insulin diminished after adjustment (-0.05 SD [-0.11; 0.02]).

CONCLUSION

rs7903146-T is associated with a decreased insulin concentration and increased risk of T2D with opposing effects of adjustment for adiposity.

Genetic variation in the obesity gene FTO is not associated with decreased fat oxidation: the NEO study

BACKGROUND

The fat mass and obesity-associated (FTO) gene harbors the strongest common genetic variant associated with obesity. Recently, rs1421085-T to -C substitution mapped in FTO was shown to induce a developmental shift of human adipocytes from an energy-combusting beige to an energy-storing white phenotype in vitro. As browning of adipocytes selectively enhances fat oxidation (FatOx), we hypothesized that rs1421085-C in FTO is associated with deceased FatOx compared with carbohydrate oxidation (CarbOx) and an increased respiratory quotient (RQ).

METHODS

In the Netherlands Epidemiology of Obesity study, a population-based cohort study of middle-aged individuals (45-65 years), anthropometry and genotyping was performed (n=5744), in addition to indirect calorimetry (n=1246). With linear regression analyses, we examined associations of rs1421085 genotype with FatOx, CarbOx and RQ.

RESULTS

In the total study population, 36.7% carried the rs1421085-TT genotype, 47.6% rs1421085-CT and 15.7% rs1421085-CC. Mean (s.d.) age was 56 (6) years, mean (s.d.), body mass index (BMI) was 26.3 (4.4) kg m^-2 and 56% of the total population were women. Measures of adiposity (difference, 95% confidence interval) were higher in CC carriers compared with that in rs1421085-TT carriers: BMI +0.56 (0.15, 0.98) kg m^-2, waist circumference +1.25 (0.02, 2.49) cm and total body fat mass +1.21 (0.28, 2.14) kg. However, no differences in mean FatOx (+2.5 (-2.4, 7.4) mg min^-1), CarbOx (-6.1 (-17.4, 5.2) mg min^-1) or RQ (-0.01 (-0.02, 0.01)) were observed between the two genotypes.

CONCLUSIONS

We observed no evidence for associations of rs1421085 in FTO with FatOx and RQ. This indicates that the rs1421085-C allele in FTO induces obesity likely via other pathways than via reduced FatOx.

Vitamin D serum levels are cross-sectionally but not prospectively associated with late-life depression

OBJECTIVE

The evidence for a prospective association of vitamin D deficiency with the occurrence of late-life depression is limited. We aimed to study the long-term association between vitamin D serum levels and depression in a large population-based study of older adults.

METHOD

We included 3251 participants from the Rotterdam Study, aged 55 and older with 32 400 person-years follow-up for depression. Baseline 25-hydroxyvitamin D (25(OH)D) serum levels were analyzed continuously and categorically. Repeated depressive symptoms' questionnaire assessments were used to assess the change of depressive symptoms. Semistructured psychiatric interviews, and GP records were used to assess incident major depressive disorder according to DSM-IV criteria.

RESULTS

Low serum vitamin D levels were cross-sectionally associated with more depressive symptoms. However, low 25(OH)D serum levels were not prospectively associated with change of depressive symptoms (unstandardized beta = 0.02, 95% CI = -0.23; 0.26) or incident MDD (hazard ratio = 0.95, 95% CI = 0.86; 1.05).

CONCLUSION

We observed a cross-sectional but no prospective association between serum vitamin D levels and depression. A cross-sectional association in the absence of the longitudinal association can mostly be attributed to reverse causality or residual confounding. Probably, vitamin D deficiency is not an independent risk factor for depression but co-occurs with late-life depression.

The long-term risk of recognized and unrecognized myocardial infarction for depression in older men

BACKGROUND

The association between myocardial infarction (MI) and depression is well described. Yet, the underlying mechanisms are unclear and the contribution of psychological factors is uncertain. We aimed to determine the risk of recognized (RMI) and unrecognized (UMI) myocardial infections on depression, as both have a similar impact on cardiovascular health but differ in psychological epiphenomena.

METHOD

Participants of the Rotterdam Study, 1823 men aged ⩾55 years, were followed for the occurrence of depression. RMI and UMI were ascertained using electrocardiography and medical history at baseline. We determined the strength of the association of RMI and UMI with mortality, and we studied the relationship of RMI and UMI with depressive symptoms and the occurrence of major depression.

RESULTS

The risk of mortality was similar in men with RMI [adjusted hazard ratio (aHR) 1.71, 95% confidence interval (CI) 1.45-2.03] and UMI (aHR 1.58, 95% CI 1.27-1.97). Men with RMI had on average [unstandardized regression coefficient (B) 1.14, 95% CI 0.07-2.21] higher scores for depressive symptoms. By contrast, we found no clear association between UMI and depressive symptoms (B 0.55, 95% CI -0.51 to 1.62) in men. Analysis including occurrence of major depression as the outcome were consistent with the pattern of association.

CONCLUSION

The discrepant association of RMI and UMI with mortality compared to depression suggests that the psychological burden of having experienced an MI contributes to the long-term risk of depression.

Both low circulating insulin-like growth factor-1 and high-density lipoprotein cholesterol are associated with hair loss in middle-aged women

BACKGROUND

Multiple biomarkers have been associated with hair loss in women, but studies have shown inconsistent results.

OBJECTIVES

We investigated the associations between markers of cardiovascular disease risk (e.g. serum lipid levels and hypertension) and ageing [e.g. 25-hydroxyvitamin D and insulin-like growth factor (IGF)] with hair loss in a population of middle-aged women.

METHODS

In a random subgroup of 323 middle-aged women (mean age 61·5 years) from the Leiden Longevity Study, hair loss was graded by three assessors using the Sinclair scale; women with a mean score > 1·5 were classified as cases with hair loss.

RESULTS

Every 1 SD increase in high-density lipoprotein (HDL) cholesterol was associated with a 0·65-times lower risk [95% confidence interval (CI) 0·46-0·91] of hair loss. For IGF-1 the risk was 0·68 times lower (95% CI 0·48-0·97) per 1 SD increase, independently of the other studied variables. Women with both IGF-1 and HDL cholesterol levels below the medians of the study population had a 3·47-times higher risk (95% CI 1·30-9·25) of having hair loss.

CONCLUSIONS

Low HDL cholesterol and IGF-1 were associated with a higher risk of hair loss in women. However, further studies are required to infer causal relationships.

Antidepressants and heart-rate variability in older adults: a population-based study

BACKGROUND

Tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs) may be associated with lower heart rate variability (HRV), a condition associated with increased mortality risk. We aimed to investigate the association between TCAs, SSRIs and HRV in a population-based study.

METHOD

In the prospective Rotterdam Study cohort, up to five electrocardiograms (ECGs) per participant were recorded (1991-2012). Two HRV variables were studied based on 10-s ECG recordings: standard deviation of normal-to-normal RR intervals (SDNN) and root mean square of successive RR interval differences (RMSSD). We compared the HRV on ECGs recorded during use of antidepressants with the HRV on ECGs recorded during non-use of any antidepressant. Additionally, we analysed the change in HRV on consecutive ECGs. Those who started or stopped using antidepressants before the second ECG were compared with non-users on two ECGs.

RESULTS

We included 23 647 ECGs from 11 729 participants (59% women, mean age 64.6 years at baseline). Compared to ECGs recorded during non-use of antidepressants (n = 22 971), SDNN and RMSSD were lower in ECGs recorded during use of TCAs (n = 296) and SSRIs (n = 380). Participants who started using TCAs before the second ECG had a decrease in HRV and those who stopped had an increase in HRV compared to consistent non-users (p < 0.001). Starting or stopping SSRIs was not associated with HRV changes.

CONCLUSION

TCAs were associated with a lower HRV in all analyses, indicating a real drug effect. For SSRIs the results are mixed, indicating a weaker association, possibly due to other factors.

Utilization patterns of antidepressants between 1991 and 2011 in a population-based cohort of middle-aged and elderly

BACKGROUND

In middle-aged and older patients in whom antidepressant use increased in last decades, patterns of use might be of concern The objective of this study was to investigate the patterns of prevalence, incidence and duration of antidepressant use in an ageing population.

METHODS

All participants (aged>45 years) from the population-based Rotterdam Study were followed from January 1st 1991 until death, loss to follow-up, or end of the study period (December 31st 2011). Antidepressant drug dispensing, based on pharmacy records, were subdivided into Tricyclic Antidepressants (TCAs), Selective Serotonin Reuptake Inhibitors (SSRIs) and other antidepressants. One-year prevalence, 5-year incidence and duration of antidepressant use were calculated.

RESULTS

Yearly prevalence of antidepressant use increased from 3.9% in 1991 to 8.3% of the population in 2011. The increase in SSRI use was 5.8-fold, whereas use of other antidepressants doubled and TCA use remained stable over time. Incidence of all antidepressants decreased from 23.9 to 14.2 per 1000 person-years between 1992 and 2011. The duration of a first treatment episode increased over time.

CONCLUSION

Despite the prevalence of antidepressant use increased over time, incidence did not, which is most likely explained by a longer treatment duration and recurrent episodes.

Serum insulin-like growth factor 1 and facial ageing: high levels associate with reduced skin wrinkling in a cross-sectional study

BACKGROUND

Insulin-like growth factor (IGF)-1 is a growth factor that can influence fibroblast functioning, with effects including the inhibition of collagenases and the induction of collagen expression.

OBJECTIVES

To assess whether serum IGF-1, IGF-binding protein (IGFBP)3 and the ratio between IGF-1 and IGFBP3, as a measure of IGF-1 bioavailability, are associated with facial ageing and skin wrinkling.

METHODS

From a random sample comprising 617 subjects from the Leiden Longevity Study, perceived age and skin wrinkling were assessed from facial photographs, and IGF-1 and IGFBP3 were measured in serum. The associations were assessed using linear regression models, adjusted for chronological age, sex, body mass index, smoking and sun exposure.

RESULTS

Across tertiles of the ratio of IGF-1 to IGFBP3, and after adjusting for all potential confounding factors, the mean perceived age decreased from 60·6 years in the lowest tertile to 59·5 years in the highest (P = 0·045). Similarly, the mean skin wrinkling grade decreased from 4·8 in the lowest tertile to 4·5 in the highest (P = 0·011). Adding skin wrinkling as a covariate in the analysis between IGF-1 and perceived age diminished this association.

CONCLUSIONS

This study demonstrates that a higher ratio of IGF-1 to IGFBP3 associates with a lower perceived age, via its association with reduced skin wrinkling. Whether high IGF-1 levels actually delay the accumulation of skin wrinkling now needs investigating.

[Internal migration by municipality, 1992]

Trends in internal migration in the Netherlands in 1992 are examined. "In 1992 the total internal mobility in the Netherlands amounted to 103 per 1,000 of the average population against about 100 at the beginning of the eighties.... The level of internal mobility as well as the proportion of intramunicipal changes of residence in big municipalities is higher on average than in small ones." (SUMMARY IN ENG)

[Increase in residential mobility in the Netherlands in 1992]

Data on residential mobility in the Netherlands for 1992 are analyzed and compared by region and family characteristics of movers. "During 1992, 742 thousand persons changed address in family context, whereas 828 thousand persons moved individually. The moving families counted on average 2.94 persons." (SUMMARY IN ENG)

Linking of immigrant flow and stock data in the Netherlands; present and future possibilities

The authors examine ways currently under consideration to link data on the resident population and on immigrants in the Netherlands. "An important development is the introduction of a new computerized population registration system in the near future. One of the features in the new system is that each inhabitant will be identified by a unique identification number. This promises well for opportunities in matching data at the individual level. It is therefore expected that in the new situation it will be possible to better link immigrant stock and flow data."