Causal Mediation Programs in R, Mplus, SAS, SPSS, and Stata

Guide to Decomposition of Causal Effects Into Mediation, Interaction, and Direct Effects: Case Study on Aerobic Exercise and Parkinson Disease

Mediation analysis can be applied in medical research with the aim of understanding the pathways that operate between an exposure and its effects on an outcome. This method can help to improve our understanding of pathophysiologic mechanisms and may guide the choice of potential treatment strategies. Traditional mediation analysis decomposes the total effect of an intervention on the outcome into 2 effects: (1) an indirect effect, from exposure using a mediator to the outcome, and (2) a direct effect, directly from exposure to outcome. A limitation of this method is that it assumes no interaction between the exposure and the mediator, which can either lead to an over- or underestimation of clinically relevant effects. The "4-way decomposition" method has the advantage of overcoming this limitation. Specifically, the total effect of an exposure on the outcome is decomposed into 4 elements: (1) reference interaction (interaction only), (2) mediated interaction (mediation and interaction), (3) the pure indirect effect (mediation but not interaction), and (4) the direct effect (no mediation and no interaction). We provide a guide to select the most appropriate method to investigate and decompose any causal effect given the research question at hand. We explain the application of the 4-way decomposition and illustrate this with a real-world example of how aerobic exercise may influence motor function in persons with Parkinson disease.

Single-Cell Patch-Clamp/Proteomics of Human Alzheimer's Disease iPSC-Derived Excitatory Neurons Versus Isogenic Wild-Type Controls Suggests Novel Causation and Therapeutic Targets

Standard single-cell (sc) proteomics of disease states inferred from multicellular organs or organoids cannot currently be related to single-cell physiology. Here, a scPatch-Clamp/Proteomics platform is developed on single neurons generated from hiPSCs bearing an Alzheimer's disease (AD) genetic mutation and compares them to isogenic wild-type controls. This approach provides both current and voltage electrophysiological data plus detailed proteomics information on single-cells. With this new method, the authors are able to observe hyperelectrical activity in the AD hiPSC-neurons, similar to that observed in the human AD brain, and correlate it to ≈1400 proteins detected at the single neuron level. Using linear regression and mediation analyses to explore the relationship between the abundance of individual proteins and the neuron's mutational and electrophysiological status, this approach yields new information on therapeutic targets in excitatory neurons not attainable by traditional methods. This combined patch-proteomics technique creates a new proteogenetic-therapeutic strategy to correlate genotypic alterations to physiology with protein expression in single-cells.

The effects and potential mechanisms of essential metals on the associations of polycyclic aromatic hydrocarbons with blood cell-based inflammation markers

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) are well-acknowledged pro-inflammatory chemicals, but their associations with blood cell-based inflammatory biomarkers need further investigation. Moreover, the effects and mechanisms of essential metals on PAH-related inflammation remain poorly understood.

OBJECTS

To elucidate the associations of PAHs on inflammatory biomarkers, as well as the effects and mechanisms of essential metals on these associations.

METHODS

A cross-sectional study was conducted on 1388 coke oven workers. We analyzed the modification effects of key essential metal(s) on PAHs-inflammatory biomarkers associations. To explore the possible mechanisms from an inflammation perspective, we performed a bioinformatic analysis on the genes of PAHs and essential metals obtained from the Comparative Toxicogenomics Database (CTD) and performed a mediation analysis.

RESULTS

We observed associations of PAHs and essential metals with lymphocyte-to-monocyte ratio (LMR) (P < 0.05). PAH mixtures were inversely associated with LMR (βQGC-index = -0.18, P < 0.001), with 1-hydroxypyrene (1-OH-Pyr) being the most prominent contributor (weight = 63.37%), whereas a positive association between essential metal mixtures and LMR was observed (βQGC-index = 0.14, P < 0.001), with tin being the most significant contributor (weight = 51.61%). An inverse association of 1-OH-Pyr with LMR was weakened by increased tin exposure (P < 0.05). The CTD database showed that PAHs and tin compounds co-regulated 22 inflammation-associated genes, but they regulated most genes in opposite directions. Further identified the involvement of oxidative stress and mediation analysis showed that the mediation effect of 8-hydroxydeoxyguanosine (8-OHdG) on 1-OH-Pyr-LMR association presented heterogeneity between low and high tin tertile groups (I2 = 37.84%).

CONCLUSION

1-OH-Pyr and tin were significantly associated with LMR. Modification effects indicated that the inverse association of 1-OH-Pyr with LMR was mitigated with an increase in tin. The mediation effect of 8-OHdG on the inverse association of 1-OH-Pyr with LMR may be partially dependent on tin.

Widening Educational Inequalities in Physical Health Due to the Obesity Trend?-A Mediation Analysis Using the German Socio-Economic Panel Study

Objectives

This study examined the contribution of obesity to the development of educational inequalities in physical health.

Methods

We used data from the German Socio-Economic Panel for the period 2002-2020. Physical health was measured with the modified SF12-questionnaire. Logistic regression analyses were applied to estimate time trends. The Relative Index of Inequality (RII) and the Slope Index of Inequality (SII) were calculated to examine educational inequalities. The role of obesity as a mediator was analyzed using the Karlson-Holm-Breen (KHB) method.

Results

Over time, educational inequalities in obesity as well as impaired physical health widened in men and women, particularly among those aged 30-49 years. For individuals with a low level of education at this age, the probability of impaired physical health increased significantly by 7.7%-points in women and 9.4%-points in men. Of this increase, 25.9% for women and 14.8% for men could be attributed to the increase in obesity.

Conclusion

Our findings suggest that the steeper rise in obesity among individuals with a low level of education partly explains the observed widening in educational inequalities in physical health.

Does health literacy mediate the relationship between socioeconomic status and health related outcomes in the Belgian adult population?

BACKGROUND

Health literacy (HL) has been put forward as a potential mediator through which socioeconomic status (SES) affects health. This study explores whether HL mediates the relation between SES and a selection of health or health-related outcomes.

METHODS

Data from the participants of the Belgian health interview survey 2018 aged 18 years or older were individually linked with data from the Belgian compulsory health insurance (n = 8080). HL was assessed with the HLS-EU-Q6. Mediation analyses were performed with health behaviour (physical activity, diet, alcohol and tobacco consumption), health status (perceived health status, mental health status), use of medicine (purchase of antibiotics), and use of preventive care (preventive dental care, influenza vaccination, breast cancer screening) as dependent outcome variables, educational attainment and income as independent variables of interest, age and sex as potential confounders and HL as mediating variable.

RESULTS

The study showed that unhealthy behaviours (except alcohol consumption), poorer health status, higher use of medicine and lower use of preventive care (except flu vaccination) were associated with low SES (i.e., low education and low income) and with insufficient HL. HL partially mediated the relationship between education and health behaviour, perceived health status and mental health status, accounting for 3.8-16.0% of the total effect. HL also constituted a pathway by which income influences health behaviour, perceived health status, mental health status and preventive dental care, with the mediation effects accounting for 2.1-10.8% of the total effect.

CONCLUSIONS

Although the influence of HL in the pathway is limited, our findings suggest that strategies for improving various health-related outcomes among low SES groups should include initiatives to enhance HL in these population groups. Further research is needed to confirm our results and to better explore the mediating effects of HL.

Associations Between Metabolic Obesity Phenotypes and Pathological Characteristics of Papillary Thyroid Carcinoma

OBJECTIVE

The association between obesity, metabolic dysregulation, and the aggressive pathological traits of papillary thyroid carcinoma (PTC) continues to be a contentious issue. To date, no investigations have examined the impact of metabolic status on the malignant pathological features of PTC in relation to obesity.

METHODS

This research involved 855 adult patients with PTC from Shandong Provincial Hospital, classified into 4 groups based on metabolic and obesity status: metabolically healthy nonobese, metabolically unhealthy nonobese (MUNO), metabolically healthy obese, and metabolically unhealthy obese. We employed logistic regression to investigate the relationship between these metabolic obesity phenotypes and PTC's pathological characteristics. Mediation analysis was also performed to determine metabolic abnormalities' mediating role in the nexus between obesity and these characteristics.

RESULTS

Relative to metabolically healthy nonobese individuals, the metabolically unhealthy obese group was significantly associated with an elevated risk of larger tumor sizes and a greater number of tumor foci in PTC. Mediation analysis indicated that obesity directly influences tumor size, whereas its effect on tumor multifocality is mediated through metabolic dysfunctions. Specifically, high-density lipoprotein cholesterol levels were notably associated with tumor multifocality within obese subjects, serving as a mediator in obesity's impact on this trait.

CONCLUSION

The concurrent presence of obesity and metabolic dysregulation is often connected to more aggressive pathological features in PTC. The mediation analysis suggests obesity directly affects tumor size and indirectly influences tumor multifocality via low high-density lipoprotein cholesterol levels.

Carotid Intima-Media Thickness and Improved Stroke Risk Assessment in Hypertensive Black Adults

BACKGROUND

We aim to determine the added value of carotid intima-media thickness (cIMT) in stroke risk assessment for hypertensive Black adults.

METHODS

We examined 1,647 participants with hypertension without a history of cardiovascular (CV) disease, from the Jackson Heart Study. Cox regression analysis estimated hazard ratios (HRs) for incident stroke per standard deviation increase in cIMT and quartiles while adjusting for baseline variables. We then evaluated the predictive capacity of cIMT when added to the pool cohort equations (PCEs).

RESULTS

The mean age at baseline was 57 ± 10 years. Each standard deviation increase in cIMT (0.17 mm) was associated with approximately 30% higher risk of stroke (HR 1.27, 95% confidence interval: 1.08-1.49). Notably, cIMT proved valuable in identifying residual stroke risk among participants with well-controlled blood pressure, showing up to a 56% increase in the odds of stroke for each 0.17 mm increase in cIMT among those with systolic blood pressure <120 mm Hg. Additionally, the addition of cIMT to the PCE resulted in the reclassification of 58% of low to borderline risk participants with stroke to a higher-risk category and 28% without stroke to a lower-risk category, leading to a significant net reclassification improvement of 0.22 (0.10-0.30).

CONCLUSIONS

In this community-based cohort of middle-aged Black adults with hypertension and no history of CV disease at baseline, cIMT is significantly associated with incident stroke and enhances stroke risk stratification.

In-Hospital Formula Feeding Hindered Exclusive Breastfeeding: Breastfeeding Self-Efficacy as a Mediating Factor

Breastfeeding self-efficacy (BSE), defined as a mother's confidence in her ability to breastfeed, has been confirmed to predict the uptake of exclusive breastfeeding (EBF). Early experiences during the birth hospital stay, especially in-hospital formula feeding (IHFF), can impact both EBF and maternal breastfeeding confidence. Therefore, our objective was to examine the association between IHFF and EBF outcomes and investigate whether this association is influenced by BSE. The study included 778 infants from a larger cohort study conducted in 2021, with a one-year follow-up in rural areas of Sichuan Province, China. We used a causal mediation analysis to estimate the total effect (TE), natural direct (NDE), and nature indirect effects (NIE) using the paramed command in Stata. Causal mediation analyses revealed that IHFF was negatively associated with EBF (TE odds ratio = 0.47; 95% CI, 0.29 to 0.76); 28% of this association was mediated by BSE. In the subgroup analysis, there were no significant differences in the effects between parity subgroups, as well as between infant delivery subgroups. Our study found that IHFF hindered later EBF and that BSE mediated this association. Limiting the occurrence of in-hospital formula feeding or improving maternal breastfeeding self-efficacy is likely to improve exclusive breastfeeding outcomes.

A methodological study of exposome based on an open database: Association analysis between exposure to metal mixtures and hyperuricemia

BACKGROUND

Exposome recognizes that humans are constantly exposed to multiple environmental factors, and elucidating the health effects of complex exposure mixtures places greater demands on analytical methods.

OBJECTS

We aimed to explore the association between mixed exposure to metals and hyperuricemia (HUA), and highlight the potential of explainable machine learning (EML) and causal mediation analysis (CMA) for application in the analysis of exposome data.

METHODS

Pre-pandemic data from the National Health and Nutrition Examination Survey (NHANES) 2011-2020 and a total of 13780 individuals were included. We first used traditional statistical models (multiple logistic regression (MLR) and restricted cubic spline regression (RCS)) and EML to explore associations between mixed metals exposures and HUA, followed by the CMA using the 4-way decomposition method to analyze the interaction and mediation effects among BMI or estimated glomerular filtration rate (eGFR), metals and HUA.

RESULTS

The prevalence of HUA was 18.91% (2606/13780). The MLR showed that mercury (Q4 vs Q1: OR = 1.08, 95% CI:1.02-1.14) and lead (Q4 vs Q1: OR = 1.23, 95% CI:1.13-1.34) were generally positively associated with HUA. Higher concentrations of lead, mercury, selenium and manganese were associated with the increased odds of HUA, and BMI and eGFR were the top two variables attributable to the risk of developing HUA in the EML. Subgroup analyses from the MLR and EML consistently demonstrated the positive relationship between exposure to lead, mercury and selenium in participants with BMI <25 kg/m2 and BMI ≥30 kg/m2. BMI mediated 32.12% of the association between lead exposure and HUA, and the interaction between BMI and lead accounted for 3.88% of the association in the CMA.

CONCLUSIONS

Heavy metals can increase the HUA risk and BMI or eGFR can mediate and interact with metals to cause HUA. Future studies based on exposome can attempt to utilize the EML and CMA.

The contribution of parity to ethnic differences in mothers' body mass index in the Netherlands: A Blinder-Oaxaca decomposition approach

Women of Turkish and Moroccan origin in the Netherlands are relatively likely to have an unhealthy bodyweight. This study sheds light on how ethnic differences in parity, i.e., the number of times a female carried pregnancies to a viable gestational age, contribute to body mass index (BMI) differences between Turkish-born and Moroccan-born mothers aged 35 + and their native Dutch counterparts. We applied a Blinder-Oaxaca decomposition approach to pooled data from four migrant surveys based on national probability samples (n = 2,532). Unlike conventional mediation analyses, the Blinder-Oaxaca approach recognizes that the association between parity and bodyweight may vary across different groups. Our results indicated that Turkish-born and Moroccan-born mothers in the Netherlands had more children and a higher BMI than native Dutch mothers. Regression analyses moreover showed that the parity-BMI gradient was steeper for Turkish-born mothers than for native Dutch mothers. Decomposition using the Blinder-Oaxaca approach indicated that the higher number of children of Turkish-born and Moroccan-born mothers compared to native Dutch mothers contributed substantially to the higher mean BMI in the former groups. The steeper parity-BMI gradient in Turkish-born mothers further amplified the contribution of parity to the higher mean BMI of Turkish-born mothers as compared to native Dutch mothers. Future research is needed to assess to which extent the steep parity-BMI gradient in Turkish-born mothers can be explained by relatively strong barriers to a healthy lifestyle that Turkish-born mothers of a larger number of children may face due to a relatively strongly gendered division of household and childrearing tasks.

Adherence to Healthy Dietary Patterns and Glioma: A Matched Case-Control Study

Recent studies have revealed a putative relationship between diet and glioma development and prognosis, but few studies have examined the association between overall diet and glioma risk. This study, conducted in China, employed a hospital-based case-control approach. The researchers utilized an a priori method based on dietary data to evaluate compliance scores for five healthy dietary patterns (the Mediterranean diet, the Dietary Approaches to Stop Hypertension (DASH) diet, the Mediterranean-DASH diet Intervention for Neurodegenerative Delay (MIND) diet, the Paleolithic diet, and the Planetary Health Diet) in 1012 participants. At the same time, data-driven methods were used to explore the association between dietary patterns and glioma via principal component analysis (PCA). In the multivariate model, adhering to the Mediterranean diet (odds ratio (OR) = 0.29; 95% confidence interval (95% CI): 0.17-0.52), the DASH diet (OR = 0.09; 95% CI: 0.04-0.18), the MIND diet (OR = 0.25; 95% CI: 0.14-0.44), and the Paleolithic diet (OR = 0.13; 95% CI: 0.06-0.25) was associated with a reduced glioma risk. The results of PCA suggested that increasing the intake of plant-based foods and fish and limiting foods rich in carbohydrates, fats, and salts were associated with a reduced glioma risk. There was a substantial nonlinear dose-response association between glioma and the Mediterranean diet score. However, the DASH diet score, the MIND diet score, and the Paleolithic diet score exhibited linear dose-response relationships. Therefore, this study finds that dietary patterns may be an influencing factor for glioma risk.

Tutorial on causal mediation analysis with binary variables: An application to health psychology research

Mediation analysis has been widely applied to explain why and assess the extent to which an exposure or treatment has an impact on the outcome in health psychology studies. Identifying a mediator or assessing the impact of a mediator has been the focus of many scientific investigations. This tutorial aims to introduce causal mediation analysis with binary exposure, mediator, and outcome variables, with a focus on the resampling and weighting methods, under the potential outcomes framework for estimating natural direct and indirect effects. We emphasize the importance of the temporal order of the study variables and the elimination of confounding. We define the causal effects in a hypothesized causal mediation chain in the context of one exposure, one mediator, and one outcome variable, all of which are binary variables. Two commonly used and actively maintained R packages, mediation and medflex, were used to analyze a motivating example. R code examples for implementing these methods are provided. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

A brief primer on conducting regression-based causal mediation analysis

OBJECTIVE

We provide an overview of regression-based causal mediation analysis in the field of traumatic stress and guidance on how to conduct mediation analysis using our R package regmedint.

METHOD

We discuss the causal interpretations of the quantities that causal mediation analysis estimates, including total, direct, and indirect effects, especially when the interaction between exposure and mediator is permitted. We discuss the assumptions that must be fulfilled for mediation analyses to validly estimate these causal quantities, discuss suitable study designs for assessing mediation, and describe how causal mediation analysis differs from traditional methods of mediation. To illustrate how to conduct and interpret mediation analysis using our R package regmedint, we use data from a published longitudinal study to assess the extent to which children's externalizing behavior mediates changes in parental negative feelings during the COVID-19 lockdown. We compare the results to those obtained using traditional methods, thus illustrating the importance of accounting for exposure-mediator interaction when an interaction may be present.

RESULTS

When the exposure and the mediator interact, traditional methods can provide estimates of direct and indirect effects that differ from those provided by more flexible causal mediation methods. When the exposure and the mediator do not interact, traditional methods and causal mediation method may estimate similar direct and indirect effects depending on the model specification.

CONCLUSIONS

In contrast to traditional methods of mediation analysis, regression-based causal mediation methods seek to estimate specific interventional quantities, not mere associations, and the causal methods explicitly allow for exposure-mediator interactions. We recommend using these methods by default rather than using more restrictive traditional methods. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Chinese Dietary Indices and Glioma: New Insights of a Case-Control Study in the Chinese Population

Identifying modifiable factors in primary prevention strategies is a typical goal of glioma epidemiology. Among many glioma risk factors, diet was always considered as one. Most of the relevant studies thus far were concentrated on the West. It was crucial to investigate the connection between the Chinese diet and gliomas given the stark variations between western and eastern diets. A food frequency questionnaire including 114 items was used to investigate the food intake of the study subjects. The Chinese Dietary Quality Index (CDQI), the Chinese Dietary Balance Index (CDBI), the Dietary Antioxidant Index (DAI), the Dietary Inflammation Index (DII), and the Chinese Healthy Eating Index (CHEI) were calculated based on the data provided by the food frequency questionnaire to evaluate dietary quality, dietary balance, dietary antioxidants, dietary inflammation and adherence to the Chinese dietary guidelines in 506 glioma patients and 506 controls, respectively. After adjusting covariates, CHEI (OR = 0.90, 95% CI: 0.88-0.93) and DAI (OR = 0.61, 95% CI: 0.54-0.70) were correlated to a reduced glioma risk, and CDBI-based undernutrition (OR = 1.08, 95% CI: 1.06-1.12) and overnutrition (OR = 1.14, 95% CI: 1.09-1.20) and DII (OR = 2.20, 95% CI: 1.81-2.68) were correlated to an elevated glioma risk. Moreover, restrictive cubic spline analysis showed that there were significant nonlinear dose-response relationships between CHEI, CDBI, DAI, DII, and glioma. Therefore, adhering to the Chinese dietary guidelines was connected with a lower glioma risk, and undernutrition and overnutrition in the Chinese diet were associated with an increased risk of glioma.

Association of Maternal Cigarette Smoking with Neonatal Death: A Population-Based Cohort Study

INTRODUCTION

Maternal pregnancy smoking has adverse perinatal outcomes and the relationship between maternal smoking and neonatal death has not been fully elucidated. We aimed to examine the risk of neonatal death in relation to maternal smoking and to quantify potential mediators of these associations.

METHODS

We did a population-based cohort study using Period Linked Birth-Infant Death data from 2016 to 2019 in the US National Vital Statistics System. The exposure was maternal smoking status. The main outcome was neonatal death. Association between maternal smoking and neonatal death was estimated through logistic regression. Mediation analysis was performed to assess the extent to which the association between maternal smoking and neonatal death was mediated by neonatal complications.

RESULTS

The final sample consisted of 14,717,020 mothers with live singleton births. The overall neonatal mortality rate was 2.2 per 1,000 live births. Maternal pregnancy smoking was associated with an increased risk of neonatal death {adjusted odds ratio (aOR, 1.33 [95% CI, 1.28-1.38]; p < 0.001)}, while smoking cessation during the whole pregnancy showed a comparable risk of neonatal death with nonsmokers (aOR, 1.06 [95% CI, 0.99-1.14]; p = 0.116). Mediation analysis indicated that the association between pregnancy smoking and neonatal death might be mainly mediated by preterm birth and low Apgar score at 5 min.

CONCLUSIONS

Maternal pregnancy smoking, regardless of pregnancy trimester and intensity, was associated with increased risk of neonatal death. Efforts are needed for policymakers to promote smoking cessation before pregnancy, and professional perinatal care should be provided for those who smoked during pregnancy.

Maternal weight and paediatric health use: mediating role of adverse birth outcomes: a retrospective cohort study

BACKGROUND

Maternal pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) above or below recommendations have been associated with increased paediatric health service utilization as well as increased risk of adverse birth outcomes, including small for gestational age (SGA) and preterm birth (PTB). SGA and PTB are associated with numerous adverse health outcomes in the child, including delayed growth, motor and cognitive impairment. Previous research has identified birth weight and gestational age on the causal pathway in the association between maternal pre-pregnancy BMI and child hospital admissions, there are no studies to date to quantify this relationship across other areas of health service utilization, nor the impact of gestational weight gain. This study aimed to assess if SGA or PTB partially explain the association between maternal weight and paediatric health service utilization.

METHODS

The study population consisted of all women who delivered a singleton, live infant in Ontario between 2012 and 2014, and was assembled from data contained in the provincial birth registry. Health service utilization over the first 24 months following birth was examined by linking data from the registry with other provincial health administrative databases housed at ICES. The mediating roles of PTB and SGA were assessed using the Baron-Kenny method and causal mediation analysis.

RESULTS

A total of 204,162 infants were included in the analysis of maternal pre-pregnancy BMI and 171,127 infants were included in the GWG analysis. The small magnitude of association between maternal BMI and paediatric health service utilization impacted our ability to estimate the indirect effect of maternal BMI through adverse birth outcomes (adjusted indirect effect = 0.00). 56.7% of the association between below recommended GWG and increased hospitalizations was attributed to PTB, while 6.8% of the association was attributed to SGA.

CONCLUSION

Paediatric hospitalizations may be partially attributable to PTB and SGA in children born to mothers with below-recommended GWG. However, maternal weight also appears to be related to increased paediatric health service utilization independent of PTB and SGA.

Effect of the decreased frequency of going out on the association between anxiety and sleep disorder during the COVID-19 pandemic: a mediation analysis

PURPOSE

The objective of the present study was to examine the relationship between anxiety and sleep disorder during the COVID-19 pandemic and to evaluate whether sleep disorder is mediated by the decreased frequency of going out.

METHODS

The data of a total of 1976 residents aged 18 years and over who had responded to a self-reported questionnaires at a health survey in 2020 were analyzed. The subjects were divided into four groups based on their response to the questionnaire on anxiety about the COVID-19 pandemic. Sleep disorder was measured using the Athens Insomnia Scale (AIS). A cross-sectional analysis was performed to examine the association between anxiety about the COVID-19 pandemic and AIS scores. Mediation analysis was used to calculate the association between anxiety and AIS scores during the COVID-19 pandemic, with decreased frequency of going out as a potential mediating variable.

RESULTS

In the cross-sectional study, the level of anxiety about the COVID-19 pandemic was significantly associated with the AIS score (p < 0.001). On mediation analysis, the direct effect of the relationship showed that anxiety positively influenced AIS scores (β = 0.283, p < 0.01). The indirect effect of the relationship showed that the decreased frequency of going out positively mediated the relationship between anxiety and AIS scores (β = 0.342, p < 0.05). The decreased frequency of going out accounted for almost 10% of the AIS score.

CONCLUSION

The present study found that anxiety about the COVID-19 pandemic was significantly associated with sleep disorder, with the decreased frequency of going out mediating this association.

Overcoming blinding confounds in psychedelic randomized controlled trials using biomarker driven causal mediation analysis

INTRODUCTION

There is great interest in the use of psychedelic-assisted therapies to treat a range of mental health conditions and initial randomized controlled trials (RCTs) have generated positive results. However, the effect sizes reported in psychedelic RCTs are likely inflated due to expectancy effects due to the de-blinding of both participants and study personnel to treatment allocation caused by the distinctive psychoactive effects of psychedelic drugs.

AREAS COVERED

An introduction to causal inference for RCTs, the underlying assumptions, and potential confounders along with graphical illustrations is provided. It is proposed that causal mediation analysis using objectively measured mediating biomarkers could be used to identify causal pathways between treatment and outcome in psychedelic RCTs, even with de-blinding of participants and give greater confidence as to the mechanistic basis and efficacy of psychedelic therapies.

EXPERT OPINION

It is argued that psychedelic therapies should not be approved as licensed medicines until causal pathways are clearly established between treatment and outcome. Potential downsides of doing so include, future indication expansion based on low quality clinical trial evidence, the approval of other therapies based on similarly low-quality evidence, and the potential for efficacy to change over time after approvals has been granted.

Gut Microbiota Taxon-Dependent Transformation of Microglial M1/M2 Phenotypes Underlying Mechanisms of Spatial Learning and Memory Impairment after Chronic Methamphetamine Exposure

Methamphetamine (METH) exposure may lead to cognitive impairment. Currently, evidence suggests that METH exposure alters the configuration of the gut microbiota. However, the role and mechanism of the gut microbiota in cognitive impairment after METH exposure are still largely unknown. Here, we investigated the impact of the gut microbiota on the phenotype status of microglia (microglial phenotypes M1 and microglial M2) and their secreting factors, the subsequent hippocampal neural processes, and the resulting influence on spatial learning and memory of chronically METH-exposed mice. We determined that gut microbiota perturbation triggered the transformation of microglial M2 to M1 and a subsequent change of pro-brain-derived neurotrophic factor (proBDNF)-p75NTR-mature BDNF (mBDNF)-TrkB signaling, which caused reduction of hippocampal neurogenesis and synaptic plasticity-related proteins (SYN, PSD95, and MAP2) and, consequently, deteriorated spatial learning and memory. More specifically, we found that Clostridia, Bacteroides, Lactobacillus, and Muribaculaceae might dramatically affect the homeostasis of microglial M1/M2 phenotypes and eventually contribute to spatial learning and memory decline after chronic METH exposure. Finally, we found that fecal microbial transplantation could protect against spatial learning and memory decline by restoring the microglial M1/M2 phenotype status and the subsequent proBDNF-p75NTR/mBDNF-TrkB signaling in the hippocampi of chronically METH-exposed mice. IMPORTANCE Our study indicated that the gut microbiota contributes to spatial learning and memory dysfunction after chronic METH exposure, in which microglial phenotype status plays an intermediary role. The elucidated "specific microbiota taxa-microglial M1/M2 phenotypes-spatial learning and memory impairment" pathway would provide a novel mechanism and elucidate potential gut microbiota taxon targets for the no-drug treatment of cognitive deterioration after chronic METH exposure.

Mediation Effect of Body Mass Index on the Association of Urinary Nickel Exposure with Serum Lipid Profiles

The objective of this study was to determine the relationship of urinary nickel (U-Ni) exposure to serum lipid profiles and the mediation effect of body mass index (BMI) in a US general population. We analyzed the cross-sectional data from 3517 participants in the National Health and Nutrition Examination Survey (NHANES) (2017-March 2020). Multivariable linear regression and restricted cubic spline (RCS) regression were conducted to explore the association of U-Ni with four serum lipids and four lipids-derived indicators. Mediation analysis was performed to examine the effect of BMI on the relationship between U-Ni levels and serum lipid profiles. Compared with the lowest quartile, the β with 95% confidence intervals (CIs) in the highest quartile were - 12.83 (- 19.42, - 6.25) for total cholesterol (TC) (P for trend < 0.001), - 12.76 (- 19.78, - 5.74) for non-high-density lipoprotein cholesterol (non-HDL-C) (P for trend = 0.001) and - 0.29 (- 0.51, - 0.07) for TC/HDL-C (P for trend = 0.007) in the fully adjusted model. RCS plots showed the linear association of log₂-transformed U-Ni levels with TC, non-HDL-C and TC/HDL-C (P for nonlinearity = 0.294, 0.152, and 0.087, respectively). Besides, BMI decreased monotonically in correlation with increasing U-Ni levels (P for trend < 0.001). Mediation analysis revealed that BMI significantly mediated the relationship of U-Ni to TC, non-HDL-C and TC/HDL-C with mediated proportions of 11.17%, 22.20% and 36.44%, respectively. In summary, our findings suggest that BMI mediates the negative association of U-Ni with TC, non-HDL-C, and TC/HDL-C in the US general population.

Maternal comorbidity and adverse perinatal outcomes in survivors of adolescent and young adult cancer: A cohort study

OBJECTIVE

To evaluate risks of preterm birth (PTB) and severe maternal morbidity (SMM) in female survivors of adolescent and young adult cancer and assess maternal comorbidity as a potential mechanism. To determine whether associations differ by use of assisted reproductive technology (ART).

DESIGN

Retrospective cohort.

SETTING

Commercially insured females in the USA.

SAMPLE

Females with live births from 2000-2019 within a de-identified US administrative health claims data set.

METHODS

Log-binomial regression models estimated relative risks of PTB and SMM by cancer status and tested for effect modification. Causal mediation analysis evaluated the proportions explained by maternal comorbidity.

MAIN OUTCOME MEASURES

PTB and SMM.

RESULTS

Among 46 064 cancer survivors, 2440 singleton births, 214 multiple births and 2590 linked newborns occurred after cancer diagnosis. In singleton births, the incidence of PTB was 14.8% in cancer survivors versus 12.4% in females without cancer (aRR 1.19, 95% CI 1.06-1.34); the incidence of SMM was 3.9% in cancer survivors versus 2.4% in females without cancer (aRR 1.44, 95% CI 1.13-1.83). Cancer survivors had more maternal comorbidities before and during pregnancy; 26% of the association between cancer and PTB and 30% of the association between cancer and SMM was mediated by maternal comorbidities. Tests for effect modification of cancer status on perinatal outcomes by ART were non-significant.

CONCLUSIONS

Preterm birth and SMM risks were modestly increased after cancer. Significant proportions of elevated risks may result from increased comorbidities. ART did not significantly modify the association between adolescent and young adult cancer and adverse perinatal outcomes. The prevention and treatment of comorbidities provides an opportunity to improve perinatal outcomes among cancer survivors.

Racial/Ethnic Disparities in Cervical Cancer Stage at Diagnosis: Mediating Effects of Neighborhood-level Socioeconomic Deprivation

BACKGROUND

Mortality from cervical cancer has declined steadily in the United States over the past several decades due to widespread screening for precancerous and early-stage cervical cancer (ECC), which are significantly easier to treat compared with late-stage cervical cancer (LCC). Unequal screening access continues to cause significant racial/ethnic disparities in cervical cancer diagnosis stage. This study examined the underlying role of neighborhood-level socioeconomic disadvantage as a potential mediator of the association between race/ethnicity and cervical cancer diagnosis stage.

METHODS

We analyzed Texas Cancer Registry data for cervical cancer cases diagnosed among women ages 18 or older from 2010 to 2018. We performed causal mediation analyses of the association between race/ethnicity and cervical cancer stage at diagnosis mediated by neighborhood-level socioeconomic disadvantage.

RESULTS

Of the 9,192 women with cervical cancer, 4,720 (51.3%) had LCC at diagnosis. Compared with non-Hispanic white (NHW) women (106.13, standard deviation (SD) = 13.32), non-Hispanic Black (NHB; 111.46, SD = 9.55) and Hispanic (112.32, SD = 9.42) women had higher area deprivation index (ADI) and had greater odds of LCC diagnosis [total effects: adjusted odds ratios (AOR) = 1.29 (95% CI, 1.11-1.46) and AOR 1.14 (95% CI, 1.03-1.25), respectively]. Approximately 34.7% and 71.6% of the disparity in LCC diagnosis were attributable to higher neighborhood socioeconomic disadvantage among NHB and Hispanic women, respectively.

CONCLUSIONS

LCC disparity varied by race/ethnicity and was partly attributable to neighborhood disadvantage. The disparity among Hispanic women due to neighborhood deprivation was twice as high among NHB women.

IMPACT

Findings may be used to develop targeted race- and place-specific interventions to improve cancer care equity.

The Nexus of Violent Victimization, Mental Health, and Employment: Findings From a Sample of Post-Incarcerated Individuals

The goals of this study were to assess the prevalence of victimization among people who are transitioning from prison to the community, and to examine the nexus of violent victimization during reentry, mental health, and weekly work hours. The participants (n = 724; average age = 29.09 years) were interviewed before release, and in the 3rd, 9th, and 15th months into reentry. Longitudinal data about their mental health, work hours, family environment, and victimization were collected. We drew on Agnew's general strain theory and employed multilevel longitudinal modeling to examine how victimization affected respondents' work hours via mental health. Findings revealed that greater exposure to violent victimization deteriorated mental health among respondents. Furthermore, an indirect effect between victimization and reduced work capacity operating through poor mental health was observed at the between-person level. These results underscored the alarmingly high prevalence of victimization among reentering individuals and that maintaining stable employment, a critical step of reintegration after imprisonment, is difficult for reentering individuals when they become a victim of violence and suffer mental health deterioration. Implications for addressing victimization among people transitioning out of prison are discussed.

The relationship between physical activity and subjective cognitive decline: Evidence from the behavioral risk factor surveillance system (BRFSS)

BACKGROUND

Studies have shown that subjective cognitive decline (SCD) is a major risk factor for mild cognitive impairment or even dementia, but the relationship between physical activity (PA) and SCD is still unclear. The goal of current study is to address how various physical activities relate to SCD.

METHODS

216,593 adults from the Behavioral Risk Factor Surveillance System (BRFSS) were included in this study. We measured SCD and PA with participants' self-report. With the unconditional logistic regression model, the association between PA and SCD was investigated. We used a four-way decomposition method to explore the mediation roles of depression between PA and SCD. The nearest matching method of propensity score and multinomial propensity score were used to reduce the effects of confounding factors.

RESULTS

Compared with those inactive, the weighted adjusted odds ratios (AORs) of SCD among those who were physically active were <1 (p < 0.005), regardless of the type of PA. The top three PA in weighted AORs were: running (AOR: 0.51, 95 % CI: 0.50-0.52), aerobics exercise (AOR: 0.55, 95 % CI: 0.53-0.56), and weightlifting (AOR: 0.60, 95 % CI: 0.59-0.62). The dose-response relationship between PA and SCD was found. Participants who engaged in PA for 241-300 min per week (AOR: 0.61, 95 % CI: 0.59-0.62) or exercised metabolic equivalent of 801-1000 per week (AOR: 0.62, 95 % CI: 0.62-0.65) had the lowest risk of SCD.

CONCLUSIONS

Regardless of the specific PA types, engaging in PA is associated with a reduced risk of having SCD, and people who engage in running had the lowest risk of SCD. There was a dose-response relationship between PA and SCD, and PA-based interventions should be developed accordingly to prevent cognitive deterioration in older age.

Environmental polycyclic aromatic hydrocarbon exposure is associated with low back pain

Several studies have assessed the influence of several often-ignored environmental factors on low back pain (LBP), but the effects of environmental polycyclic aromatic hydrocarbon (PAH) exposure on LBP are unclear. During the 2001-2004 cycle of the National Health and Nutrition Examination Survey (NHANES), our study was given to a representative sample of US participants older than 20 (N = 2743). Environmental PAH exposure was calculated using urinary PAH metabolite concentrations. Weighted logistic regression was performed to assess the connection between PAH levels and LBP, with mediation analysis utilised to explore the underlying mechanism. Levels of 1-hydroxynaphthalene (1-OHNa), 2-hydroxynaphthalene (2-OHNa) and total PAHs had a statistically significant positive association with LBP. The odds ratios per 1-unit increase for log-transformed levels of urinary 1-OHNa, 2-OHNa, and total PAHs with LBP were 1.01 (95% CI 1.02-1.19), 1.19 (95% CI 1.04-1.36) and 1.16 (95% CI 1.03-1.32), respectively. The results revealed a strong dose-response association between 1-OHNa, 2-OHNa, total PAHs, and LBP risk. Subgroup analysis indicated that 2&3-OHPh may increase the risk of LBP in the lower family income subgroup. Gamma-glutamyl transaminase (GGT), known as a biomarker of oxidative stress, was strongly related to PAHs. The relationship between total PAHs and LBP was mediated in part by GGT. Our study demonstrates associations between environmental PAH exposure and LBP that need more research to determine the precise effects of various PAH compounds on LBP.

Life satisfaction among persons living with dementia and those without dementia

BACKGROUND

Despite possible major adverse cognitive, physical, social, and behavioral consequences, little is known about how persons living with dementia perceive satisfaction with life, a key component of well-being. We sought to examine (i) whether persons living with dementia perceive a lower level of satisfaction compared to their peers without dementia and (ii) whether the associations between individual characteristics and life satisfaction are different between persons living with and without dementia.

METHODS

Using a nationally representative sample of community-dwelling older adults aged ≥70 years in the U.S. from the Health and Retirement Study, we compared scores on the Satisfaction with Life Scale (SWLS), a self-reported 5-item scale ranging from 1 to 7 (more satisfaction), between persons with probable dementia (n = 341) and those without (n = 5530), adjusting for individual characteristics. We also tested whether the associations between the individual characteristics and SWLS differ by dementia status.

RESULTS

Scores on SWLS did not differ between persons with probable dementia and those without when adjusting for individual characteristics including limitations in activities of daily living (ADL) (adjusted difference, -0.09; 95% CI, -0.33 to +0.15; p-value, 0.45). However, dementia status was associated with lower life satisfaction through the mediation of limitations in ADL (total effect, -0.29; bootstrapped 95% CI, -0.47 to -0.12). Most individual characteristics associated with lower life satisfaction were similar in the two groups, including younger age, more limitations in ADL, and depression. Less wealth was associated with lower satisfaction among persons without dementia but not among those with probable dementia.

CONCLUSIONS

Dementia status was only modestly associated with lower life satisfaction through the mediation of limitations in ADL among participants who were able to provide response. Future research is warranted to determine whether life satisfaction can be used as a meaningful outcome when evaluating well-being among persons living with dementia.

Experiences of discrimination and oral health-related quality of life among foreign-born older Chinese Americans: Does resilience play a mediating role?

OBJECTIVES

It is well-established that racial discrimination influences quality of life, but there is scarce evidence about how racial discrimination affects oral health-related quality of life (OHRQoL). Furthermore, the pathways linking racial discrimination and OHRQoL remain unknown. Guided by the integrative framework of immigration, ageing, and oral health, psychosocial stressors and resources exert influences on OHRQoL. In addition, according to the compensatory model of resilience, resilient resources could counteract risk exposures to stressors given specific outcomes. Hence, this study examined the relationship between experiences of discrimination and OHRQoL and investigated resilience as a mediator in such a relationship among older Chinese immigrants.

METHODS

Data came from the Population Study of Chinese Elderly in Chicago collected between 2017 and 2019. The working sample included 3054 foreign-born older Chinese Americans aged 60 years or older. OHRQoL was measured by seven items from the Geriatric Oral Health Assessment Index. Experiences of discrimination (yes or no) were measured by the 9-item Experiences of Discrimination instrument. Resilience was measured by the 10-item Connor Davidson Resilience Scale. Mediation analysis was conducted to examine the direct and indirect pathways towards OHRQoL.

RESULTS

Experiences of discrimination were directly associated with poorer OHRQoL (b = -0.98, P < .05). Resilience partially mediated the relationship between discrimination experiences and OHRQoL. Specifically, discrimination experiences were associated with weaker resilience (b = -1.58, P < .05), and weaker resilience was associated with poorer OHRQoL (b = 0.06, P < .05).

CONCLUSIONS

Findings illustrate the importance of studying racial discrimination and resilience in OHRQoL. Interventions need to consider individuals' discrimination experiences and stress coping abilities to promote OHRQoL.

Causal mediation effects in single case experimental designs

Single case experimental designs (SCEDs) are used to test treatment effects in a wide range of fields and consist of repeated measurements for a single case throughout one or more baseline phases and throughout one or more treatment phases. Recently, mediation analysis has been applied to SCEDs. Mediation analysis decomposes the total treatment-outcome effect into a direct and indirect effect, and therefore aims to unravel the causal processes underlying treatment-outcome effects. The most recent methodological advancement for mediation analysis is the development of causal mediation analysis methodology which clarifies the necessary causal assumptions for mediation analysis. The goal of this article is to derive the causal mediation effects and corresponding standard errors based on piecewise linear regression models for the mediator and outcome and to evaluate the performance of these regression estimators and standard errors. Whereas previous studies estimated the direct and indirect effects as either the change in level or change in trend, we showed that the causal direct and indirect effects incorporate both the change in level and change in trend. Based on our simulation study we showed that for the causal indirect effects, Monte Carlo confidence intervals provided accurate (i.e., p = .05) Type I error rates and higher statistical power than normal theory confidence intervals. For the causal direct effects and total effect, normal theory confidence intervals provided accurate Type I error rates and higher statistical power than the Monte Carlo confidence intervals. Limitations and future directions are discussed. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

The association between food insecurity and cognitive impairment among the US adults: The mediation role of anxiety or depression

BACKGROUND

Using a nationally representative sample, this study aimed to examine (1) socio-demographic and health-related disparities in cognitive impairment, (2) the association between food insecurity and cognitive impairment, and (3) the mediation role of anxiety or depression in the pathway between food insecurity and cognitive impairment.

METHODS

Cross-sectional data of 28,508 adults from the 2020 National Health Interview Survey were analyzed. Multivariable logistic regression models were used to estimate associations with cognitive impairment. Mediation analyses were conducted using the four-way decomposition method under a counterfactual framework.

RESULTS

Disparities in cognitive impairment were observed across socio-demographic and health-related characteristics (all p < 0.0001). Food insecurity was significantly associated with cognitive impairment in the overall population and the magnitude of the association was greater for the young or middle-aged, females and non-Hispanic Blacks than the general population (AOR ranged from 1.19 to 2.54, all p < 0.01). With anxiety as a mediator, 28.66 % of the total effect of food insecurity on cognitive impairment was attributable to mediation only, and 22.39 % was attributable to interaction (between food insecurity and anxiety) and mediation. With depression as a mediator, 22.33 % of the total effect was attributable to mediation only, and 16.00 % was attributable to interaction (between food insecurity and depression) and mediation.

LIMITATIONS

The cross-sectional design prevents inference of causality.

CONCLUSIONS

Ensuring available and adequate food resources is important to prevent adverse cognitive outcomes. Clinical interventions or treatments for anxiety or depression may help improve cognitive function.

Sleep deprivation altered encoding of basolateral amygdala on fear acquisition

Sleep deprivation (SD) may lead to the development of fear- and anxiety-related emotional disorders. However, the neural mechanisms underlying the effects of SD on fear acquisition are unclear. Here, we tested whether and how SD influences the behavioral and neural manifestations of fear acquisition. We found that subjective fear ratings and objective fear indices (skin conductance response [SCR]) in the SD group were greater than those in the control group during fear acquisition, suggesting that SD facilitated fear acquisition (nSD = 18 and ncontrol = 23 for self-reported rating analysis; nSD = 10 and ncontrol = 10 for SCR analysis). Neuroimaging data showed that the SD group exhibited stronger activity in the left basolateral amygdala (BLA) and left superficial amygdala (SFA). Moreover, the left BLA activity, which positively correlated with the objective fear indices, significantly mediated the effect of SD on fear acquisition. Together, the present findings indicate that SD facilitates fear acquisition by augmenting threat-specific encoding in the BLA, which may be a potential biomarker of the risk of developing fear-related disorders under traumatic and distressing situations.

Association Between Serum Trace Heavy Metals and Liver Function Among Adolescents

BACKGROUND

Exposure to metals has been associated with liver-related disease. Few studies have explored the effect of sex stratification on adolescent liver function.

METHOD

From the National Health and Nutrition Examination Survey (2011-2016), 1143 subjects aged 12-19 years were selected for analysis. The outcome variables were the levels of alanine aminotransferase (ALT), aspartate aminotransferase, and gamma-glutamyl transpeptidase.

RESULTS

The results showed a positive association between serum zinc and ALT in boys (odds ratio [OR], 2.37; 95% confidence interval [CI], 1.11-5.06). Serum mercury was associated with an increase in ALT level in girls (OR, 2.73; 95% CI, 1.14-6.57). Mechanistically, the efficacy mediated by total cholesterol accounted for 24.38% and 6.19% of the association between serum zinc and ALT.

CONCLUSIONS

The results imply that serum heavy metals were associated with the risk of liver injury, possibly mediated by serum cholesterol, in adolescents.

Obesity indicators as mediators of the association between age at menopause and blood pressure values

Having a later age at menopause is associated with having a higher blood pressure (BP) value, but the mediation pathways remain unclear. We quantitatively examined the mediation effects of various obesity indicators using baseline data from phase 4 of the Guangzhou Biobank Cohort Study. The product of coefficients approach and bootstrapping procedures were used to assess the mediation effects of body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR) on the association between age at menopause and BP values. Age, education, occupation, family income, smoking, drinking, diet, physical activity, age at menarche, number of births, fasting glucose, triglycerides, and high-density lipoprotein cholesterol were adjusted as covariates. Of 5429 women with natural menopause, the mean age and menopausal age were 60.0 (standard deviation = 5.8) and 50.3 (3.1) years, respectively. The prevalence of hypertension was 29.6%. In women with a menopausal age of ≥50 years, BMI, WC, WHR and WHtR showed significant mediation effects on the positive association between menopausal age and BP. The adjusted proportion (95% confidence interval) of the mediation effects for those variables were 26.04% (10.40-116.82%), 25.92% (10.19-108.57%), 14.11% (3.59-62.78%), and 23.17% (8.70-95.81%), respectively, for systolic BP values and 22.59% (10.72-53.60%), 20.67% (9.83-49.31%), 9.21% (2.73-23.92%), and 17.19% (7.56-41.31%) for diastolic BP values. In women with a menopausal age of <50 years, no significant association between age at menopause and systolic/diastolic BP values was found. In conclusion, obesity indicators showed significant mediating effects on the association between having a later age at menopause and having a higher BP value. Further longitudinal studies with detailed and accurate measurements of metabolic changes after menopause and sufficient follow-up are warranted to confirm these results. We demonstrated obesity indicators showed significant mediating effects on the association between later age at menopause (≥50 years) and higher BP.

Association of nurse staffing and unit occupancy with mortality and morbidity among very preterm infants: a multicentre study

OBJECTIVE

In a healthcare system with finite resources, hospital organisational factors may contribute to patient outcomes. We aimed to assess the association of nurse staffing and neonatal intensive care unit (NICU) occupancy with outcomes of preterm infants born <33 weeks' gestation.

DESIGN

Retrospective cohort study.

SETTING

Four level III NICUs.

PATIENTS

Infants born 23-32 weeks' gestation 2015-2018.

MAIN OUTCOME MEASURES

Nursing provision ratios (nursing hours worked/recommended nursing hours based on patient acuity categories) and unit occupancy rates were averaged for the first shift, 24 hours and 7 days of admission of each infant. Primary outcome was mortality/morbidity (bronchopulmonary dysplasia, severe neurological injury, retinopathy of prematurity, necrotising enterocolitis and nosocomial infection). ORs for association of exposure with outcomes were estimated using generalised linear mixed models adjusted for confounders.

RESULTS

Among 1870 included infants, 823 (44%) had mortality/morbidity. Median nursing provision ratio was 1.03 (IQR 0.89-1.22) and median unit occupancy was 89% (IQR 82-94). In the first 24 hours of admission, higher nursing provision ratio was associated with lower odds of mortality/morbidity (OR 0.93, 95% CI 0.89 to 0.98), and higher unit occupancy was associated with higher odds of mortality/morbidity (OR 1.19, 95% CI 1.04 to 1.36). In causal mediation analysis, nursing provision ratios mediated 47% of the association between occupancy and outcomes.

CONCLUSIONS

NICU occupancy is associated with mortality/morbidity among very preterm infants and may reflect lack of adequate resources in periods of high activity. Interventions aimed at reducing occupancy and maintaining adequate resources need to be considered as strategies to improve patient outcomes.

The Characteristics of Cognitive Proficiency in Patients with Acute Neuromyelitis Optica Spectrum Disease and its Correlation with Serum Aquaporin-4 Antibody Titer

Objective: To explore the characteristics and dynamic evolution of cognitive impairment in patients with neuromyelitis optica spectrum disorder (NMOSD). Methods: Twenty-five patients with acute NMOSD and 30 age-matched healthy individuals were consecutively recruited in this study. The Montreal Cognitive Assessment (MoCA), Chinese Version of Rey Auditory Vocabulary Learning Test (CRAVLT), Verbal Fluency Test (VFT), Digital Span Test (DST), Paced Auditory Serial Addition Task 3/2s version (PASAT-3/2), Rey−Osterrieth Complex Figure Test (ROCF) and Stroop Color and Word Test (CWT) were used to evaluate cognitive function. The correlations between cognitive function and serum aquaporin-4 (AQP-4) antibody titer were analyzed. Results: Sixty-four percent of patients with acute NMOSD had cognitive dysfunction. MoCA (p < 0.001), CRAVLT-N7 (p = 0.004), CRAVLT-N8 (p = 0.011), ROCF-C (p = 0.005), ROCF-R (p < 0.001), PASAT-3 (p = 0.013), PASAT-2 (p = 0.001) and CWT-A (p = 0.017) were significantly worse in patients with acute NMOSD than those in control group. During follow-up visits, significant differences of serum AQP-4 antibody titers were still noted in NMOSD patients (p < 0.001), while no significant differences were found by MoCA. Conclusion: A high number of patients with acute NMOSD suffer from cognitive dysfunction. Serum AQP-4 antibody titers can decrease during disease remission, while obvious cognitive decline in these patients still exists.

Associations of hiatus hernia with CT-based interstitial lung changes: the MESA Lung Study

BACKGROUND

Hiatus hernia (HH) is prevalent in adults with pulmonary fibrosis. We hypothesised that HH would be associated with markers of lung inflammation and fibrosis among community-dwelling adults and stronger among MUC5B (rs35705950) risk allele carriers.

METHODS

In the Multi-Ethnic Study of Atherosclerosis, HH was assessed from cardiac and full-lung computed tomography (CT) scans performed at Exam 1 (2000-2002, n=3342) and Exam 5 (2010-2012, n=3091), respectively. Percentage of high attenuation areas (HAAs; percentage of voxels with attenuation between -600 and -250 HU) was measured from cardiac and lung scans. Interstitial lung abnormalities (ILAs) were examined from Exam 5 scans (n=2380). Regression models were used to examine the associations of HH with HAAs, ILAs and serum matrix metalloproteinase-7 (MMP-7), and adjusted for age, sex, race/ethnicity, educational attainment, smoking, height, weight and scanner parameters for HAA analysis.

RESULTS

HH detected from Exam 5 scans was associated with a mean percentage difference in HAAs of 2.23% (95% CI 0.57-3.93%) and an increase of 0.48% (95% CI 0.07-0.89%) per year, particularly in MUC5B risk allele carriers (p-value for interaction=0.02). HH was associated with ILAs among those <80 years of age (OR for ILAs 1.78, 95% CI 1.14-2.80) and higher serum MMP-7 level among smokers (p-value for smoking interaction=0.04).

CONCLUSIONS

HH was associated with more HAAs over time, particularly among MUC5B risk allele carriers, and ILAs in younger adults, and may be a risk factor in the early stages of interstitial lung disease.

COVID-19 Concerns, Perceived Stress, and Increased Alcohol Use Among Adult Women in the United States

The objective of this study was to assess the direct and indirect (via perceived stress) effects of different types of pandemic-related concerns and increased alcohol use among adult women in the United States (US). We conducted a secondary analysis of cross-sectional survey data from April 2020 for adult females in the US who use alcohol (n = 1,089). The indirect effect model accounted for 19% of the variance in perceived stress and 8% of the variance in reporting increased alcohol use compared to no change or decreased use. Path analysis results indicated that concerns about isolation (odds ratio [OR] = 1.027, 95% confidence interval [CI] = 1.013-1.046), job/finances (OR = 1.025, 95% CI = 1.007-1.065), basic needs (OR = 1.021, 95% CI = 1.008-1.047), and concerns about government (OR = 1.038, 95% CI = 1.014-1.179]) were significantly related to reporting increased alcohol use through perceived stress. These findings can inform timely public health interventions to minimize alcohol-related harm among women.

Afraid but misinformed: Conspiracist beliefs cancel the positive influence of fear of COVID-19 on vaccination intentions - Findings from a Romanian sample

Understanding the factors that make people more likely to refuse vaccination against COVID-19 is crucial in order to design public health messages efficient in increasing vaccination rates. As COVID-19 creates risks of seriously damaging health effects, fear of this disease is as a significant determinant of vaccination intentions, as indicated by past research. Nevertheless, this positive influence may be limited in people who do not consider vaccines as a solution to protect against COVID-19, especially those who hold conspiracist beliefs about the new coronavirus and, implicitly, about the newly developed vaccines. The present study examined in a cross-sectional design on a convenience sample (N = 564) the joint effect of fear of COVID-19 and conspiracist beliefs on vaccination intentions, advancing past research on their independent influences. Furthermore, we investigated and controlled the effects of perceived risk of catching COVID-19, trust in medical experts, attitude towards vaccination and socio-demographical characteristics (i.e., gender, age, and education), previously found to be associated to COVID-19 vaccination intentions. We also tested the effect of ambivalence towards vaccination, i.e., the degree to which people simultaneously hold positive and negative evaluations of this intervention, as the widespread misinformation on the new coronavirus and its vaccines may induce ambivalence on this latter issue in many people. The results showed that the positive effect of fear of COVID-19 on vaccination intentions emerged only in participants who tend not to endorse conspiracist ideas on the new coronavirus. Moreover, higher vaccine hesitancy was found in participants with higher ambivalence towards vaccination, in those who perceive the risk of being contaminated by the new coronavirus as low, and in those with more negative attitudes towards vaccines in general. Vaccine ambivalence also emerged as a mediator of the negative effects of conspiracist beliefs about COVID-19 on vaccination intentions. This pattern of findings suggests the public messages emphasizing the risks of COVID-19 should also combat misinformation in order to maximize vaccine uptake.

Plant-Based Diets and the Incidence of Asthma Symptoms among Elderly Women, and the Mediating Role of Body Mass Index

We aimed to test the hypothesis that adherence to a healthful plant-based diet (hPDI) is associated with a subsequent decrease in the incidence of asthma symptoms, with an opposite association with adherence to an unhealthful plant-based diet (uPDI). In addition, we evaluated a potential mediating role of body mass index (BMI) and the modifying effect of smoking. Among 5700 elderly women from the French Asthma-E3N study with dietary data in 1993 and 2005, we assessed the incidence of asthma symptoms in 2018 among women with no asthma symptoms in 2011. BMI was evaluated in 2008. Mediation analyses in the counterfactual framework were used to disentangle total, direct, and indirect effects mediated by BMI. We found that both healthful and unhealthful plant-based diets were associated with a lower incidence of asthma symptoms over time, mediated by BMI (OR (95%CI) for the indirect effect: 0.94 (0.89-1.00) for hPDI and 0.92 (0.70-1.00) for uPDI)). Associations with both healthful and unhealthful PDIs were mediated by changes in BMI by 33% and 89%, respectively. Plant-based diets (healthful and unhealthful) were associated with subsequently reduced incidences of asthma symptoms over time, partly or almost totally mediated by BMI according to their nutritional quality.

Living a Calling During COVID-19: A Resource Gain Perspective

Massive disruptions to work and threats to employee well-being due to the coronavirus disease 2019 (COVID-19) pandemic have highlighted the need to identify resources which enable employees to gain other valuable resources. Using a resource gain perspective, we examined the role of living a calling as a potentially robust resource, enabling employees to gain work readiness during the COVID-19 pandemic, and, in turn, resulting in a greater well-being in the form of lower job strain. Using a sample of clergy (N = 216) from various denominations, we provide initial evidence that living a calling may be associated with lower levels of job strain through increased COVID-19 work readiness. This study underscores the relevance of living a calling in a time of high potential or actual loss of resources.

Water From the Lake of Memory: The Regulatory Model of Nostalgia

We organize the literature on triggers and functions of nostalgia by advancing a regulatory model in which the emotion serves as a homeostatic corrective (i.e., a process that establishes and maintains a relatively stable psychological equilibrium) that countervails the negative effects of psychological perturbations and adverse environmental conditions. We illustrate complementary approaches to testing this model as it applies to transient, or state-level, nostalgia and show how the model can be generalized to different levels of analysis, including chronic, or trait-level, nostalgia and collective nostalgia. We then formulate a proposal for future research inspired by recent developments in causal mediation analysis and conclude with a discussion of the model’s potential boundary conditions.

Impact on outcomes of measuring lactates prior to ICU in unselected heterogeneous critically ill patients: A propensity score analysis

BACKGROUND

Elevated blood lactate levels were reported as effective predictors of clinical outcome and mortality in ICU. However, there have been no studies simply comparing the timing of measuring lactates before vs. after ICU admission.

METHODS

A total of 19,226 patients with transfer time ≤ 24 hr were extracted from the Medical Information Mart for Intensive Care IV database (MIMIC-IV). After 1:1 propensity score matching, the patients were divided into two groups: measuring lactates within 3 hr before (BICU group, n = 4,755) and measuring lactate within 3 hr after ICU admission(AICU group, n = 4,755). The primary and secondary outcomes were hospital mortality, hospital 28-day mortality, ICU mortality, ICU length of stay (LOS), hospital LOS, and restricted mean survival time (RMST).

RESULTS

Hospital, hospital 28-day, and ICU mortality were significantly higher in AICU group (7.0% vs.9.8%, 6.7% vs. 9.4%, and 4.6% vs.6.7%, respectively, p<0.001 for all) Hospital LOS and ICU LOS were significantly longer in AICU group (8.4 days vs. 9.0 days and 3.0 days vs. 3.5 days, respectively, p<0.001 for both). After adjustment for predefined covariates, a significant association between the timing of measuring lactate and hospital mortality was observed in inverse probability treatment weight (IPTW) multivariate regression, doubly robust multivariate regression, and multivariate regression models (OR, 0.96 [95%CI, 0.95-0.97], OR 0.52 [95%CI, 0.46-0.60], OR 0.66 [95%CI, 0.56-0.78], respectively, p<0.001 for all), indicating the timing as a significant risk-adjusted factor for lower hospital mortality. The difference (BICU-AICU) of RMST at 28- days after ICU admission was 0.531 days (95%CI, 0.002-1.059, p<0.05). Placement of A-line and PA-catheter, administration of intravenous antibiotics, and bolus fluid infusion during the first 24-hr in ICU were significantly more frequent and faster in the BICU vs AICU group (67.6% vs. 51.3% and 126min vs.197min for A-line, 19.6% vs.13.2% and 182min vs. 274min for PA-catheter, 77.5% vs.67.6% and 109min vs.168min for antibiotics, and 57.6% vs.51.6% and 224min vs.278min for bolus fluid infusion, respectively, p<0.001 for all). Additionally, a significant indirect effect was observed in frequency (0.19879 [95% CI, 0.14061-0.25697] p<0.001) and time (0.07714 [95% CI, 0.22600-0.13168], p<0.01) of A-line replacement, frequency of placement of PA-catheter (0.05614 [95% CI, 0.04088-0.07140], p<0.001) and frequency of bolus fluid infusion (0.02193 [95%CI, 0.00303-0.04083], p<0.05).

CONCLUSIONS

Measuring lactates within 3 hr prior to ICU might be associated with lower hospital mortality in unselected heterogeneous critically ill patients with transfer time to ICU ≤ 24hr, presumably due to more frequent and faster therapeutic interventions.

Pain and Nausea Intensity, Social Function, and Psychological Well-Being among Women with Metastatic Breast Cancer

Advances in diagnostics and therapeutics have improved prognosis for metastatic breast cancer (MBC). Yet, treatment and disease burden-including experiences of pain and nausea-present practical and emotional challenges. To better support patients and enhance quality of life, deeper understanding of the pathways linking physical and psychological health is needed. To this end, we examined associations of pain and nausea with depression and anxiety among women with MBC. In doing so, we highlighted social function as a potentially important mechanism in this relationship. This observational, cross-sectional study included 148 predominantly non-Hispanic White, highly educated women living with MBC. Multivariate regression models demonstrated that more intense pain and nausea were significantly associated with higher levels of depression and anxiety (p < .001). Causal mediation analyses confirmed significant indirect effects whereby decreases in social function associated with pain and nausea contributed to depression and anxiety. Thus, our findings illustrate decreased social function as one pathway through which pain and nausea contribute to escalation of depression and anxiety. Our results, therefore, underscore the importance of supporting social function among women with MBC to potentially reduce psychological sequelae of pain and nausea.

Accommodating a Latent XM Interaction in Statistical Mediation Analysis

Statistical mediation analysis is used in the social sciences and public health to uncover potential mechanisms, known as mediators, by which a treatment led to a change in an outcome. Recently, the estimation of the treatment-by-mediator interaction (i.e., the XM interaction) has been shown to play a pivotal role in understanding the equivalence between the traditional mediation effects in linear models and the causal mediation effects in the potential outcomes framework. However, there is limited guidance on how to estimate the XM interaction when the mediator is latent. In this article, we discuss eight methods to accommodate latent XM interactions in statistical mediation analysis, which fall in two categories: using structural models (e.g., latent moderated structural equations, Bayesian mediation, unconstrained product indicator method, multiple-group models) or scoring the mediator prior to estimating the XM interaction (e.g., summed scores and factor scores, with and without attenuation correction). Simulation results suggest that finite-sample bias is low, type 1 error rates and coverage of percentile bootstrap confidence intervals and Bayesian credible intervals are close to the nominal values, and statistical power is similar across approaches. The methods are demonstrated with an applied example, syntax is provided for their implementation, and general considerations are discussed.

Association of Plasma and Cerebrospinal Fluid Alzheimer Disease Biomarkers With Race and the Role of Genetic Ancestry, Vascular Comorbidities, and Neighborhood Factors

IMPORTANCE

Differences in cerebrospinal fluid (CSF) tau Alzheimer dementia (AD) biomarkers by self-identified race have been observed in prior studies. More recently, plasma biomarkers have been gaining recognition, but whether they exhibit similar differences is unclear. Furthermore, the underlying explanation for these differences in AD biomarkers is still unexplored.

OBJECTIVES

To investigate differences in plasma biomarkers by race and genetic ancestry and explore potential underlying explanations for these differences.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study used participant data from the Brain, Stress, Hypertension, and Aging Research Program (B-SHARP), an observational study conducted in the greater Atlanta metropolitan area. Participants were enrolled from March 1, 2016, to January 1, 2020.

MAIN OUTCOMES AND MEASURES

Main outcomes were plasma and CSF amyloid-β (Aβ) 42, Aβ40, phosphorylated tau181 (p-tau181), and neurofilament light. General linear models were used for key comparisons.

EXPOSURES

Main independent variables were self-identified race and genetic ancestry. Additional variables were cardiovascular factors, APOE4, educational attainment, Area Deprivation Index, and C-reactive protein (reflecting systemic inflammation state).

RESULTS

This analysis included 617 participants (mean [SD] age, 66 [7.9] years; 300 [49%] African American and 317 [51%] White; 429 [70%] with mild cognitive impairment). On the basis of self-reported race, plasma levels of Aβ42 (adjusted mean difference, -1.20 pg/mL; 95% CI, -2.33 to -0.07 pg/mL), Aβ40 (adjusted mean difference, -37.78 pg/mL; 95% CI, -60.16 to -15.39 pg/mL), p-tau181 (adjusted mean difference, -4.66 pg/mL; 95% CI, -7.05 to -1.90 pg/mL), and neurofilament light (adjusted mean difference, -1.58; 95% CI, -2.83 to -0.19 pg/mL) were consistently lower in African American individuals after adjusting for demographic characteristics, educational attainment, cognition, APOE4, and cardiovascular factors. A similar pattern was observed in the CSF biomarkers except for Aβ42 and Aβ40. Although unadjusted analyses revealed an association between these biomarkers and African ancestry, these associations were not significant after adjusting for the same covariates. Differences by self-reported race were not explained by varied cardiovascular risk factors, C-reactive protein, educational attainment, or Area Deprivation Index.

CONCLUSIONS AND RELEVANCE

In this cross-sectional study of plasma biomarkers by race and genetic ancestry, the results indicated that plasma p-tau181, Aβ40, and NFL were lower in African American individuals based on self-reported race but not genetic ancestry. These differences were not explained by cardiovascular risks or clinical stage differences. These racial differences should be considered in clinical interpretations and clinical trial screenings to avoid an additional increase in underrepresentation of African American individuals in AD trials.

Child maltreatment, anxiety and depression, and asthma among British adults in the UK Biobank

BACKGROUND

Child maltreatment is associated with asthma in adults. We examined whether lifetime major depressive disorder (MDD) or lifetime generalised anxiety disorder (GAD) mediate an association between child maltreatment and current asthma among 81 105 British adults in the UK Biobank who completed a mental health survey and had complete data on child maltreatment, GAD, MDD, asthma and relevant covariates but no diagnosis of chronic obstructive pulmonary disease.

METHODS

Child maltreatment was ascertained based on answers to the five questions in the Childhood Trauma Screener. Two mediators, lifetime MDD and GAD, were assessed based on the Composite International Diagnostic Interview Short Form. Current asthma was defined as physician-diagnosed asthma and wheeze or whistling in the chest in the previous year. Logistic regression was used for the multivariable analysis of child maltreatment and current asthma, and a mediation analysis was conducted to estimate the contributions of lifetime MDD and lifetime GAD to the child maltreatment-current asthma association.

RESULTS

In a multivariable analysis, any child maltreatment was associated with asthma (adjusted OR 1.22, 95% CI 1.15-1.28; p<0.01). In a mediation analysis adjusted for household income, educational attainment, smoking status, pack-years of smoking and other covariates, lifetime GAD and lifetime MDD explained 21.8% and 32.5%, respectively, of the child maltreatment-current asthma association. Similar results were obtained after excluding current smokers and former smokers with ≥10 pack-years of smoking from the mediation analysis.

CONCLUSION

Our findings suggest that GAD and MDD mediate an association between child maltreatment and asthma in adults, independently of smoking.

Railway noise and diabetes among residents living close to the railways in Västra Götaland, Sweden: Cross-sectional mediation analysis on obesity indicators

Railway noise is expected to increase in Europe and Sweden as well, following recommendations for a more sustainable transportation mode. This forecasted increase might lead to higher level of noise exposure, higher population exposure and potentially increased night-time exposure. Evidence supports an effect of transportation noise on several health outcomes, including metabolic conditions such as diabetes. However, few studies were directed to railway noise; present studies on railway noise and diabetes so far show ambiguous results while some studies report an association between railway noise and obesity. The aim of this study is to investigate the relationship between railway noise and diabetes prevalence and to assess whether obesity might be a mediator in this association. The study population (N = 5381) was randomly selected from residents living within 1 km of a trafficked railway in Västra Götaland, Sweden. Survey data was combined with modelled exposures and health register data (ICD10 codes for diabetes). The study uses a cross sectional design, logistic regression analysis and a counterfactual mediation analysis. We found an increase in the prevalence of diabetes associated with the exposure to railway noise: OR = 1.33 per 10 dB increase L_den (95% CI 1.09-1.63) accounting for sociodemographic and lifestyle factors. BMI and waist circumference partially mediate the association between railway noise and diabetes. This is the first study to report an association between railway noise and diabetes in Sweden. BMI and waist circumference seem to be a potential mediators in this association. Still, future studies should further explore the mechanisms from noise to diabetes, considering different pathways in relation to obesity but also exploring other potential mediators.

Risk of large for gestational age births at early, full and late term in relation to pre-pregnancy body mass index: Mediation by gestational diabetes status

BACKGROUND

Maternal pre-pregnancy body mass index (BMI) is strongly associated with infant birthweight and the risk differs in pregnancies complicated by gestational diabetes (GDM).

OBJECTIVES

To examine the risk of large for gestational age (LGA) (≥97th percentile) singleton births at early term, full term and late term in relation to maternal pre-pregnancy BMI status mediated through GDM.

METHODS

We analysed data from the 2018 U.S. National Vital Statistics Natality File restricted to singleton term births (N = 3,229,783). In counterfactual models for causal inference, we estimated the total effect (TE), natural direct effect (NDE) and natural indirect effect (NIE) for the association of pre-pregnancy BMI with subcategories of LGA births at early, full and late term mediated through GDM, using log-binomial regression and adjusting for race/ethnicity, age, education, parity and infant sex. Proportion mediated was calculated on the risk difference scale and potential unmeasured confounders were assessed using the E-value.

RESULTS

Overall, 6.4% of women had GDM, and there were 3.6% LGA singleton term births. The highest prevalence of GDM was among pre-gestational overweight/obesity that also had the highest rates of LGA births at term. The TE estimates for the risk of LGA births were the strongest across women with higher pre-pregnancy BMI compared to women with normal pre-pregnancy BMI. The NDE estimates were higher than the NIE estimates for overweight/obese BMI status. The proportion mediated, which answers the causal question to what extent the total effect of the association between pre-pregnancy BMI and LGA births is accounted for through GDM, was the highest (up to 16%) for early term births.

CONCLUSIONS

Term singleton births make up the largest proportion in a cohort of newborns. While the percentage mediated through GDM was relatively small, health risks arising from pre-pregnancy overweight, and obesity can be substantial to both mothers and their offspring.

The gut microbiota-bile acid axis links the positive association between chronic insomnia and cardiometabolic diseases

Evidence from human cohorts indicates that chronic insomnia is associated with higher risk of cardiometabolic diseases (CMD), yet whether gut microbiota plays a role is unclear. Here, in a longitudinal cohort (n = 1809), we find that the gut microbiota-bile acid axis may link the positive association between chronic insomnia and CMD. Ruminococcaceae UCG-002 and Ruminococcaceae UCG-003 are the main genera mediating the positive association between chronic insomnia and CMD. These results are also observed in an independent cross-sectional cohort (n = 6122). The inverse associations between those gut microbial biomarkers and CMD are mediated by certain bile acids (isolithocholic acid, muro cholic acid and nor cholic acid). Habitual tea consumption is prospectively associated with the identified gut microbiota and bile acids in an opposite direction compared with chronic insomnia. Our work suggests that microbiota-bile acid axis may be a potential intervention target for reducing the impact of chronic insomnia on cardiometabolic health.

Chronic insomnia is associated with cardiometabolic diseases. Here, in two clinical cohorts (n = 7,931), authors show that gut microbiota-bile acid axis may be an intervention target to attenuate the impact of chronic insomnia on cardiometabolic health.