Perceived stress is related to lower blood pressure in a Swedish cohort

AIMS

General psychosocial stress and job strain have been related to blood pressure (BP) with conflicting results. This study sought to explore the contribution of several lifestyle factors in the relation between general psychosocial stress, job strain and BP.

METHODS

This cross-sectional study investigated the association of general stress and job strain with systolic BP (SBP) and diastolic BP in a sample of 9441 employed individuals from the EpiHealth cohort. General stress was measured by the Perceived Stress Scale. Job strain was assessed with the Job Content Questionnaire, assessing two dimensions of job strain: psychological job demand and decision latitude. Linear regression and sensitivity analysis were performed.

RESULTS

At the uncorrected model, general stress, job demand and decision latitude were all inversely associated with SBP. After further adjustment for lifestyle and health parameters, only general stress was associated with SPB (β coefficient: -0.103; 95% confidence interval -0.182 to 0.023).

CONCLUSIONS

General stress is associated with lower SBP independently of lifestyle in middle-aged adults. Our findings point towards a major contribution for job-unrelated stressors in determining SBP and support the pivotal role of lifestyle behaviours and health status in modulating the effect of stress on BP, calling for a careful selection of confounders.

Differential DNA Methylation of the Genes for Amyloid Precursor Protein, Tau, and Neurofilaments in Human Traumatic Brain Injury

Traumatic brain injury (TBI) is an established risk factor for neurodegenerative disorders and dementias. Epigenetic modifications, such as DNA methylation, may alter the expression of genes without altering the DNA sequence in response to environmental factors. We hypothesized that DNA methylation changes may occur in the injured human brain and be implicated in the neurodegenerative aftermath of TBI. The DNA methylation status of genes related to neurodegeneration; for example, amyloid beta precursor protein (APP), microtubule associated protein tau (MAPT), neurofilament heavy (NEFH), neurofilament medium (NEFM), and neurofilament light (NEFL), was analyzed in fresh, surgically resected human brain tissue from 17 severe TBI patients and compared with brain biopsy samples from 19 patients with idiopathic normal pressure hydrocephalus (iNPH). We also performed an epigenome-wide association study (EWAS) comparing TBI patients with iNPH controls. Thirty-eight CpG sites in the APP, MAPT, NEFH, and NEFL genes were differentially methylated by TBI. Among the top 20 differentially methylated CpG sites, 11 were in the APP gene. In addition, the EWAS evaluating 828,888 CpG sites revealed 308 differentially methylated CpG sites in genes related to cellular/anatomical structure development, cell differentiation, and anatomical morphogenesis. These preliminary findings provide the first evidence of an altered DNA methylome in the injured human brain, and may have implications for the neurodegenerative disorders associated with TBI.

Personality, lifestyle and job satisfaction: causal association between neuroticism and job satisfaction using Mendelian randomisation in the UK biobank cohort

Job-related stress has been associated with poor health outcomes but little is known about the causal nature of these findings. We employed Mendelian randomisation (MR) approach to investigate the causal effect of neuroticism, education, and physical activity on job satisfaction. Trait-specific genetic risk score (GRS) based on recent genome wide association studies were used as instrumental variables (IV) using the UK Biobank cohort (N = 315,536). Both single variable and multivariable MR analyses were used to determine the effect of each trait on job satisfaction. We observed a clear evidence of a causal association between neuroticism and job satisfaction. In single variable MR, one standard deviation (1 SD) higher genetically determined neuroticism score (4.07 units) was associated with -0.31 units lower job satisfaction (95% confidence interval (CI): -0.38 to -0.24; P = 9.5 × 10^-20). The causal associations remained significant after performing sensitivity analyses by excluding invalid genetic variants from GRS_Neuroticism (β(95%CI): -0.28(-0.35 to -0.21); P = 3.4 x 10^-15). Education (0.02; -0.08 to 0.12; 0.67) and physical activity (0.08; -0.34 to 0.50; 0.70) did not show any evidence for causal association with job satisfaction. When genetic instruments for neuroticism, education and physical activity were included together, the association of neuroticism score with job satisfaction was reduced by only -0.01 units, suggesting an independent inverse causal association between neuroticism score (P = 2.7 x 10^-17) and job satisfaction. Our findings show an independent causal association between neuroticism score and job satisfaction. Physically active lifestyle may help to increase job satisfaction despite presence of high neuroticism scores. Our study highlights the importance of considering the confounding effect of negative personality traits for studies on job satisfaction.

Hypermethylation-associated downregulation of microRNA-4456 in hypersexual disorder with putative influence on oxytocin signalling: A DNA methylation analysis of miRNA genes

Hypersexual disorder (HD) was proposed as a diagnosis in the DSM-5 and the classification ‘Compulsive Sexual Behavior Disorder’ is now presented as an impulse-control disorder in ICD-11. HD incorporates several pathophysiological mechanisms; including impulsivity, compulsivity, sexual desire dysregulation and sexual addiction. No previous study investigated HD in a methylation analysis limited to microRNA (miRNA) associated CpG-sites. The genome wide methylation pattern was measured in whole blood from 60 subjects with HD and 33 healthy volunteers using the Illumina EPIC BeadChip. 8,852 miRNA associated CpG-sites were investigated in multiple linear regression analyses of methylation M-values to a binary independent variable of disease state (HD or healthy volunteer), adjusting for optimally determined covariates. Expression levels of candidate miRNAs were investigated in the same individuals for differential expression analysis. Candidate methylation loci were further studied for an association with alcohol dependence in an independent cohort of 107 subjects. Two CpG-sites were borderline significant in HD – cg18222192 (MIR708)(p < 10E-05,p_FDR = 5.81E-02) and cg01299774 (MIR4456)(p < 10E-06, p_FDR = 5.81E-02). MIR4456 was significantly lower expressed in HD in both univariate (p < 0.0001) and multivariate (p < 0.05) analyses. Cg01299774 methylation levels were inversely correlated with expression levels of MIR4456 (p < 0.01) and were also differentially methylated in alcohol dependence (p = 0.026). Gene target prediction and pathway analysis revealed that MIR4456 putatively targets genes preferentially expressed in brain and that are involved in major neuronal molecular mechanisms thought to be relevant for HD, e.g., the oxytocin signalling pathway. In summary, our study implicates a potential contribution of MIR4456 in the pathophysiology of HD by putatively influencing oxytocin signalling.

A MIR4646 associated methylation locus is hypomethylated in adolescent depression

BACKGROUND

Studies of epigenetics and transcriptional activity in adolescents may provide knowledge about possible preventive strategies of depression.

METHODS

We present a methylome-wide association study (MWAS) and cohort validation analysis of depression in adolescents, in two separate cohorts: discovery (n=93) and validation data set 1 (n=78). The genome-wide methylation pattern was measured from whole blood using the Illumina 450K array. A second validation cohort, validation data set 2, consists of post-mortem brain biopsies from depressed adults (n=58). We performed a MWAS by robust multiple linear regressions of methylation to a modified risk-score assessment of depression. Methylation levels of candidate CpG sites were correlated with expression levels of the associated gene in an independent cohort of 11 healthy volunteers.

RESULTS

The methylation state of two CpG sites reliably predicted ratings of depression in adolescents (cg13227623 and cg04102384) (p<10E-06). Cohort validation analysis confirmed cg04102384 - located in the promoter region of microRNA 4646 (MIR4646) - to be hypomethylated in both validation data set 1 and validation data set 2 (p<0.05). Cg04102384 was inversely correlated to expression levels of MIR4646-3p in healthy controls (p<0.05).

LIMITATIONS

MIR4646 was not differentially expressed in a subset of samples with adolescent depression measured by qRT-PCR measurements.

CONCLUSION

We identify a specific MIR4646 associated epigenetic risk site to be associated with depression in adolescents. Cg04102384 putatively regulates gene expression of MIR4646-3p. Target gene prediction and gene set overrepresentation analysis revealed involvement of this miRNA in fatty acid elongation, a process related to omega-3 fatty acids, previously associated with depression.

A genetic risk score is significantly associated with statin therapy response in the elderly population

The ability of statins to strongly reduce low-density lipoprotein cholesterol (LDL-C) varies interindividually and is partially influenced by genetic variants. Based on a comprehensive analysis of 23 single nucleotide polymorphisms (SNPs) known to be associated with pharmacokinetics and dynamics of statins, we developed a genetic risk score to study its impact on the therapy outcome in elderly individuals under at least 5 years statin therapy. The study was performed in a population-based cohort of 1016 elderly individuals, which comprised 168 statin users investigated at age 75 and 80. Using random forest models, the major variants influencing LDL-C levels were summarized in a weighted GRS (wGRS). The wGRS was tested with lipid and glucose outcomes and validated in an independent population-based cohort including 221 statin users. Four SNPs within the APOE cluster (rs7412, rs4420638), ABCC2 (rs2002042) and CELSR/SORT1/PSRC1 (rs646776), displayed a major impact on statin efficacy. The wGRS was significantly associated with lower LDL-C at age 75 and 80. This association was replicated displaying similar results. GRS analysis is a powerful tool to evaluate the additive effects of genetic variants on statin response and to estimate the magnitude of LDL-C reduction to a considerable extent in the older population.