Browsing by Author "Van den Heuvel, Leigh Luella"

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    Cortisol levels in different tissue samples in posttraumatic stress disorder patients versus controls : a systematic review and meta-analysis protocol
    (BMC (part of Springer Nature), 2019-01-07) Van den Heuvel, Leigh Luella; Wright, Simonne; Suliman, Sharain; Stalder, Tobias; Kirschbaum, Clemens; Seedat, Soraya
    Background: Posttraumatic stress disorder (PTSD) is a disorder that develops following exposure to severely stressful events. Altered cortisol secretion has been reported in PTSD; however, results have been inconsistent. Previous meta-analyses of cortisol levels in PTSD have combined results of studies that have used different tissue samples (blood, saliva, urine) for cortisol measurement and have not included newer methods of determining cortisol levels (e.g. hair samples). In this systematic review, we will synthesise evidence from studies evaluating basal cortisol levels in PTSD patients versus controls and stratify studies according to tissue type used for cortisol measurement. We will also determine whether results from different tissue types can be pooled and if any specific tissue samples have better utility in research studies on PTSD. Methods: We will perform a systematic review of the scientific literature including all studies that have evaluated basal or baseline cortisol levels in adults with current PTSD versus controls, with and without trauma exposure. Independent reviewers will conduct searches in electronic databases (Medline, CINAHL, PTSDpubs, Web of Science, Scopus, ProQuest Dissertations & Theses A&I, ClinicalTrials.gov, and ICTRP), and additional studies will be obtained by searching the reference lists of articles. Two reviewers (LLvdH and SW) will independently conduct standardised screening, eligibility assessments, data extraction, and quality assessments before qualitative and, if appropriate, quantitative (meta-analysis and meta-regression) synthesis. Disagreements that arise at any stage will be resolved by a third reviewer (ShS). Discussion: In line with previous reviews, we expect that cortisol levels will be lower in PTSD patients than in controls, but that patterns may vary somewhat according to the tissue sample in which cortisol is measured. This systematic review will assist in developing a better understanding of the acute and chronic patterns of basal cortisol secretion in PTSD and will inform future research.
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    Hair cortisol as a neuroendocrine biomarker to evaluate the impact of chronic stress on the interaction between neuropsychiatric disorders and metabolic syndrome
    (Stellenbosch : Stellenbosch University, 2020-03) Van den Heuvel, Leigh Luella; Seedat, Soraya, 1966-; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Psychiatry.
    ENGLISH SUMMARY : Individuals with neuropsychiatric disorders (NPDs) demonstrate increased rates of cardiovascular disease (CVD) and metabolic syndrome (MetS). There is evidence of dysregulated hypothalamic pituitary adrenal (HPA) axis functioning in both NPDs and CVD and the HPA-axis may be a shared mechanistic pathway contributing to NPD-CVD comorbidity. Very few studies have, however, directly examined the association between NPDs, CVD risk and HPA-axis function. Hair cortisol concentrations (HCC), reflecting longerterm systemic cortisol levels, can provide insight into the role of HPA-axis dysregulation in the occurrence of CVD risk, as defined by MetS, in NPDs. This study was a neuroendocrine ancillary study to ‘Understanding the SHARED ROOTS (SR) of Neuropsychiatric Disorders and Modifiable Risk Factors for Cardiovascular Disease’. SR was a cross-sectional matched case-control study investigating the pathways contributing to the comorbidity of MetS in NPDs and included three NPD cohorts (posttraumatic stress disorder (PTSD), schizophrenia and Parkinson’s disease). This study investigated the role of HPA-axis dysfunction, as measured by HCC, in the three NPDs as compared to controls and in relation to NPD-MetS co-occurrence. We demonstrated that HPA-axis function was altered in the three NPDs, with higher HCC in PTSD patients than trauma exposed controls, lower HCC in patients with schizophrenia than controls and higher hair cortisone levels, but not HCC, in Parkinson’s disease patients than controls. MetS was not associated with HCC in any of the individual cohorts. The lack of significant findings related to MetS may have been due to limited statistical power to detect significant associations in the individual cohorts. Additionally, as this is one of the first studies investigating HCC in South Africa and the majority of studies have been conducted in developed regions, we sought to identify basic determinants of HCC in a South African mixed ancestry control sample. The main determinants associated with HCC were age, level of education, duration of sun exposure, hair product use, duration of sample storage and breastfeeding in women. We also demonstrated that resilience, but not self-perceived stress, was significantly inversely associated with HCC, underscoring the importance of identifying stress-resilience indicators of HCC in non-pathological samples. Finally we also found that poorer working memory performance was associated with higher HCC, suggesting an association between a neuroendocrine marker of chronic stress and working memory deficits. This is the first study to utilise a measure of longer-term HPA axis function to investigate the links between HPA-axis, NPDs and CVD risk. Considering the high burden of CVD in NPDs, this study provides a step towards better understanding the role played by chronic stress, as reflected by long-term HPA axis dysfunction, in the co-occurrence of CVD in NPDs. Furthermore, this study provides insights into the role of HPA-axis dysfunction in relation to clinical conditions and subjects of relevance to South Africa and contributes to broader geographic, cultural and ethnic representation in hair cortisol research.