Studies examining post-traumatic stress disorder (PTSD) have either emphasized a relationship between PTSD and a systemically pro-inflammatory state or identified a link between PTSD and chronic disease. The aim of this study was to evaluate the evidence for a relationship between individuals with PTSD and systemic low-grade inflammation that has been proposed to underlie chronic disease development in this population. The authors conducted a systematic review of the literature (January 2006 to April 2017) in accordance with the PRISMA statement in the following four databases: PubMed, MEDLINE, PsycINFO, and SPORTDiscus with Full Text. The search strategy was limited to articles published in peer-reviewed journals and to human studies. Nine studies measuring systemic inflammation and discussing its role in chronic disease development were selected for inclusion in this review. The association between markers of systemic inflammation and PTSD was evaluated by the measurement of a variety of systemic inflammatory markers including acute-phase proteins, complement proteins, pro- and anti-inflammatory cytokines, natural killer cells, and white blood cells. In general, systemic inflammatory biomarkers were elevated across the studies in the PTSD groups. There is evidence that PTSD is underpinned by the presence of a systemic low-grade inflammatory state. This inflammation may be the mechanism associated with increased risk for chronic disease in the PTSD population. From this, future research should focus on interventions that help to reduce inflammation, such as exercise.

Background There is inconsistency in the literature regarding the nature of hypothalamic-pituitary-adrenal (HPA) axis functionality in post-traumatic stress disorder (PTSD). Purpose The review aimed to investigate HPA axis functionality via the diurnal profile of cortisol as it relates to PTSD. Methods The authors conducted a systematic review of the literature from June 2017 – March 2019 in accordance with The PRISMA Statement in the following four databases: PubMed, MEDLINE, ScienceDirect and PsycINFO with Full Text. The search strategy was limited to articles in English language, published in peer-reviewed journals within the last decade and human studies. Search terms included “post-traumatic stress disorder” OR “PTSD”, AND “hypothalamic pituitary adrenal axis” OR “HPA axis” AND “diurnal cortisol” OR “cortisol”. PTSD sufferers of all trauma types, genders and socioeconomic statuses were included provided there was a “healthy” control group and an inclusion of reporting on inter-group measurements of diurnal cortisol profiles as a portrayal of HPA axis functionality. Results A total of 10 studies met the criteria for inclusion in this review. The association between HPA axis functionality and PTSD was evaluated by the measurement of salivary and/or plasma cortisol concentrations. Only two studies demonstrated an association between PTSD and diurnal cortisol when compared with respective control groups while three studies found no associations. The remaining five studies found partial, mostly negative associations between PTSD and diurnal cortisol. Conclusion Despite some indications of an association between PTSD and dysregulated HPA axis functionality as demonstrated by diurnal cortisol output, the current review has revealed mixed findings. As such, a complete understanding of HPA axis dysregulation as it relates to PTSD remains unestablished. Given the findings, further investigation into the relationship between PTSD trauma-exposed and non-PTSD trauma-exposed individuals and diurnal cortisol is warranted.

Heart rate variability (HRV) is an accepted method for determining autonomic nervous system activity and cardiovascular risk in various populations. This study assessed the validity and reliability of a commercially available finger photoplethysmography (PPG) system for measuring pediatric HRV in a real-world setting. Sixteen healthy children (4.06 ± 0.58 years) were recruited. The PPG system was compared to the Polar H10 heart rate (HR) sensor validated against ECG (gold standard) for HRV measurement. Seated short-term resting R-R intervals were recorded simultaneously using both systems. Recordings were performed on 3 days at the participants’ school. Paired t-tests, effect sizes and Bland–Altman analyses determined the validity of the PPG system. The relative and absolute reliability of both systems were calculated. No HRV parameters were valid for the PPG system. Polar H10 yielded moderate (0.50–0.75) to good (0.75–0.90) relative reliability with R-R intervals and the standard deviation of instantaneous and continuous R-R variability ratio showing the best results (ICCs = 0.84). Polar H10 displayed better absolute reliability with the root mean square of successive differences, R-R intervals and HR showing the lowest values (TEM% < 12%). The use of the Polar H10 and not the PPG system is encouraged for HRV measurement of young children in an educational real-world setting.

Highlights Heart rate variability and BMI are inversely related in preschool children. One unit increase in BMI resulted in a reduction in RMSSD(ln) of 0.06% Age, sex and physical activity levels did not influence this relationship.

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