A Genome-Wide Association Study and Polygenic Risk Score Analysis of Posttraumatic Stress Disorder and Metabolic Syndrome in a South African Population

Cardiometabolic Morbidity (Obesity and Hypertension) in PTSD: A Preliminary Investigation of the Validity of Two Structures of the Impact of Event Scale-Revised

Background: Posttraumatic stress disorder (PTSD) and/or specific PTSD symptoms may evoke maladaptive behaviors (e.g., compulsive buying, disordered eating, and an unhealthy lifestyle), resulting in adverse cardiometabolic events (e.g., hypertension and obesity), which may implicate the treatment of this complex condition. The diagnostic criteria for PTSD have lately expanded beyond the three common symptoms (intrusion, avoidance, and hyperarousal). Including additional symptoms such as emotional numbing, sleep disturbance, and irritability strengthens the representation of the Impact of Event Scale-Revised (IES-R), suggesting that models with four, five, or six dimensions better capture its structure compared to the original three-dimensional model. Methods: Using a convenience sample of 58 Russian dental healthcare workers (HCWs: mean age = 44.1 ± 12.2 years, 82.8% females), this instrumental study examined the convergent, concurrent, and criterion validity of two IES-R structures: IES-R3 and IES-R6. Results: Exploratory factor analysis uncovered five factors, which explained 76.0% of the variance in the IES-R. Subscales of the IES-R3 and the IES-R6 expressed good internal consistency (coefficient alpha range = 0.69-0.88), high convergent validity (item total correlations r range = 0.39-0.81, and correlations with the IES-R's total score r range = 0.62-0.92), excellent concurrent validity through strong correlations with the PTSD Symptom Scale-Self Report (PSS-SR: r range = 0.42-0.69), while their criterion validity was indicated by moderate-to-low correlations with high body mass index (BMI: r range = 0.12-0.39) and the diagnosis of hypertension (r range = 0.12-0.30). In the receiver-operating characteristic (ROC) curve analysis, all IES-R models were perfectly associated with the PSS-SR (all areas under the curve (AUCs) > 0.9, p values < 0.001). The IES-R, both hyperarousal subscales, and the IES-R3 intrusion subscale were significantly associated with high BMI. Both avoidance subscales and the IES-R3 intrusion subscale, not the IES-R, were significantly associated with hypertension. In the two-step cluster analysis, five sets of all trauma variables (IES-R3/IES-R6, PSS-SR) classified the participants into two clusters according to their BMI (normal weight/low BMI vs. overweight/obese). Meanwhile, only the IES-R, PSS-SR, and IES-R3 dimensions successfully classified participants as having either normal blood pressure or hypertension. Participants in the overweight/obese and hypertensive clusters displayed considerably higher levels of most trauma symptoms. Input variables with the highest predictor importance in the cluster analysis were those variables expressing significant associations in correlations and ROC analyses. However, neither IES-R3 nor IES-R6 contributed to BMI or hypertension either directly or indirectly in the path analysis. Meanwhile, age significantly predicted both health conditions and current smoking. Irritability and numbing were the only IES-R dimensions that significantly contributed to current smoking. Conclusions: The findings emphasize the need for assessing the way through which various PTSD symptoms may implicate cardiometabolic dysfunctions and their risk factors (e.g., smoking and the intake of unhealthy foods) as well as the application of targeted dietary and exercise interventions to lower physical morbidity in PTSD patients. However, the internal and external validity of our tests may be questionable due to the low power of our sample size. Replicating the study in larger samples, which comprise different physical and mental conditions from heterogenous cultural contexts, is pivotal to validate the results (e.g., in specific groups, such as those with confirmed traumatic exposure and comorbid mood dysfunction).

Sex-specific role of high-fat diet and stress on behavior, energy metabolism, and the ventromedial hypothalamus

BACKGROUND

Scientific evidence highlights the influence of biological sex on the relationship between stress and metabolic dysfunctions. However, there is limited understanding of how diet and stress concurrently contribute to metabolic dysregulation in both males and females. Our study aimed to investigate the combined effects of high-fat diet (HFD) induced obesity and repeated stress on fear-related behaviors, metabolic, immune, and hypothalamic outcomes in male and female mice.

METHODS

To investigate this, we used a highly reliable rodent behavioral model that faithfully recapitulates key aspects of post-traumatic stress disorder (PTSD)-like fear. We subjected mice to footshock stressor followed by a weekly singular footshock stressor or no stressor for 14 weeks while on either an HFD or chow diet. At weeks 10 and 14 we conducted glucose tolerance and insulin sensitivity measurements. Additionally, we placed the mice in metabolic chambers to perform indirect calorimetric measurements. Finally, we collected brain and peripheral tissues for cellular analysis.

RESULTS

We observed that HFD-induced obesity disrupted fear memory extinction, increased glucose intolerance, and affected energy expenditure specifically in male mice. Conversely, female mice on HFD exhibited reduced respiratory exchange ratio (RER), and a significant defect in glucose tolerance only when subjected to repeated stress. Furthermore, the combination of repeated stress and HFD led to sex-specific alterations in proinflammatory markers and hematopoietic stem cells across various peripheral metabolic tissues. Single-nuclei RNA sequencing (snRNAseq) analysis of the ventromedial hypothalamus (VMH) revealed microglial activation in female mice on HFD, while male mice on HFD exhibited astrocytic activation under repeated stress.

CONCLUSIONS

Overall, our findings provide insights into complex interplay between repeated stress, high-fat diet regimen, and their cumulative effects on health, including their potential contribution to the development of PTSD-like stress and metabolic dysfunctions, emphasizing the need for further research to fully understand these interconnected pathways and their implications for health.

The relationship between nutrient intake and executive function in adults with post-traumatic stress disorder

BACKGROUND

Executive function (EF) deficits are common in adults with post-traumatic stress disorder (PTSD). Macro- and micronutrient intake are potential modifiable factors that may influence EF in PTSD.

OBJECTIVES

To explore the relationship between the daily dietary intake of ω-3 and ω-6 polyunsaturated fatty acids (PUFAs), vitamin C, vitamin E, vitamin D, vitamin B12 and folate, and EF in adults with PTSD.

METHODS

This was a cross-sectional observational study of adults with PTSD who completed neurocognitive assessments (n = 201). Digit span backwards, spatial span backwards, Stroop test and the Ruff Figural Fluency Task were used to assess EF. FoodFinder nutrient intake based on 24-h dietary recalls was used to calculate average daily nutrient intake. Multivariable linear regression models were used to regress EF on the nutrient variables.

RESULTS

Intake of vitamin E, ω-3 PUFAs, and ω-6 PUFAs were all positively associated with planning and set-shifting, with vitamin E (adjusted β = 0.20, p = 0.004) and ω-6 (adjusted β = 0.17, p = 0.01) remaining significant after adjustment for age; sex; education and body mass index. Vitamin D intake was negatively associated with interference (adjusted β = -0.21, p = 0.01). Vitamin C, vitamin B12 and folate intake were not associated with EF.

LIMITATIONS

24-h dietary recall data is limited by recall bias. Circulating nutrient levels were not measured.

CONCLUSIONS

Dietary intake of vitamins E, ω-3 and ω-6 may be important modifiable factors affecting EF in adults with PTSD. Randomised controlled trials are needed to investigate whether micro- and macronutrient interventions can improve EF and other outcomes in PTSD.

Sexually dimorphic role of diet and stress on behavior, energy metabolism, and the ventromedial hypothalamus

Scientific evidence underscores the influence of biological sex on the interplay between stress and metabolic dysfunctions. However, there is limited understanding of how diet and stress jointly contribute to metabolic dysregulation in both males and females. To address this gap, our study aimed to investigate the combined effects of a high-fat diet (HFD) and repeated footshock stress on fear-related behaviors and metabolic outcomes in male and female mice. Using a robust rodent model that recapitulates key aspects of post-traumatic stress disorder (PTSD), we subjected mice to footshock stressor followed by weekly reminder footshock stressor or no stressor for 14 weeks while on either an HFD or chow diet. Our findings revealed that HFD impaired fear memory extinction in male mice that received initial stressor but not in female mice. Blood glucose levels were influenced by both diet and sex, with HFD-fed female mice displaying elevated levels that returned to baseline in the absence of stress, a pattern not observed in male mice. Male mice on HFD exhibited higher energy expenditure, while HFD-fed female mice showed a decreased respiratory exchange ratio (RER). Sex-specific alterations in pro-inflammatory markers and abundance of hematopoietic stem cells were observed in chronically stressed mice on an HFD in different peripheral tissues, indicating the manifestation of distinct comorbid disorders. Single-nuclei RNA sequencing of the ventromedial hypothalamus from stressed mice on an HFD provided insights into sex-specific glial cell activation and cell-type-specific transcriptomic changes. In conclusion, our study offers a comprehensive understanding of the intricate interactions between stress, diet, sex, and various physiological and behavioral outcomes, shedding light on a potential brain region coordinating these interactions.

Identifying genetic loci that are associated with changes in gene expression in PTSD in a South African cohort

The molecular mechanisms underlying posttraumatic stress disorder (PTSD) are yet to be fully elucidated, especially in underrepresented population groups. Expression quantitative trait loci (eQTLs) are DNA sequence variants that influence gene expression, in a local (cis-) or distal (trans-) manner, and subsequently impact cellular, tissue, and system physiology. This study aims to identify genetic loci associated with gene expression changes in a South African PTSD cohort. Genome-wide genotype and RNA-sequencing data were obtained from 32 trauma-exposed controls and 35 PTSD cases of mixed-ancestry, as part of the SHARED ROOTS project. The first approach utilised 108 937 single-nucleotide polymorphisms (SNPs) (MAF > 10%) and 11 312 genes with Matrix eQTL to map potential eQTLs, while controlling for covariates as appropriate. The second analysis was focused on 5638 SNPs related to a previously calculated PTSD polygenic risk score for this cohort. SNP-gene pairs were considered eQTLs if they surpassed Bonferroni correction and had a false discovery rate <0.05. We did not identify eQTLs that significantly influenced gene expression in a PTSD-dependent manner. However, several known cis-eQTLs, independent of PTSD diagnosis, were observed. rs8521 (C > T) was associated with TAGLN and SIDT2 expression, and rs11085906 (C > T) was associated with ZNF333 expression. This exploratory study provides insight into the molecular mechanisms associated with PTSD in a non-European, admixed sample population. This study was limited by the cross-sectional design and insufficient statistical power. Overall, this study should encourage further multi-omics approaches towards investigating PTSD in diverse populations.

RNA-seq analysis of gene expression profiles in posttraumatic stress disorder, Parkinson's disease and schizophrenia identifies roles for common and distinct biological pathways

Evidence suggests that shared pathophysiological mechanisms in neuropsychiatric disorders (NPDs) may contribute to risk and resilience. We used single-gene and network-level transcriptomic approaches to investigate shared and disorder-specific processes underlying posttraumatic stress disorder (PTSD), Parkinson's disease (PD) and schizophrenia in a South African sample. RNA-seq was performed on blood obtained from cases and controls from each cohort. Gene expression and weighted gene correlation network analyses (WGCNA) were performed using DESeq2 and CEMiTool, respectively. Significant differences in gene expression were limited to the PTSD cohort. However, WGCNA implicated, amongst others, ribosomal expression, inflammation and ubiquitination as key players in the NPDs under investigation. Differential expression in ribosomal-related pathways was observed in the PTSD and PD cohorts, and focal adhesion and extracellular matrix pathways were implicated in PD and schizophrenia. We propose that, despite different phenotypic presentations, core transdiagnostic mechanisms may play important roles in the molecular aetiology of NPDs.