Biological Determinants of Depression: An epidemiological approach

Understanding the biology behind depression has a long history in research. To date, no unique marker or specific etiological factor was detected. However, we know more about the possible mechanisms that predispose depression or affect clinical presentation and prognosis of depression. In this thesis, we studied various hypotheses to extend our knowledge about biological determinants of depression using an epidemiological approach. The main aims of this thesis were 1) to scrutinize the determinants and the genetic control of different functions of the HPA axis, a well-known neurohormonal correlate of depression, 2) to revisit the vascular depression hypothesis and explored the associations of non-clinical cerebrovascular alterations with depression, and 3) to explore genetic etiology of depression using the genome-wide association approach

Leapfrogging laboratories: the promise and pitfalls of high-tech solutions for antimicrobial resistance surveillance in low-income settings.

The scope and trajectory of today's escalating antimicrobial resistance (AMR) crisis is inadequately captured by existing surveillance systems, particularly those of lower income settings. AMR surveillance systems typically collate data from routine culture and susceptibility testing performed in diagnostic bacteriology laboratories to support healthcare. Limited access to high quality culture and susceptibility testing results in the dearth of AMR surveillance data, typical of many parts of the world where the infectious disease burden and antimicrobial need are high. Culture and susceptibility testing by traditional techniques is also slow, which limits its value in infection management. Here, we outline hurdles to effective resistance surveillance in many low-income settings and encourage an open attitude towards new and evolving technologies that, if adopted, could close resistance surveillance gaps. Emerging advancements in point-of-care testing, laboratory detection of resistance through or without culture, and in data handling, have the potential to generate resistance data from previously unrepresented locales while simultaneously supporting healthcare. Among them are microfluidic, nucleic acid amplification technology and next-generation sequencing approaches. Other low tech or as yet unidentified innovations could also rapidly accelerate AMR surveillance. Parallel advances in data handling further promise to significantly improve AMR surveillance, and new frameworks that can capture, collate and use alternate data formats may need to be developed. We outline the promise and limitations of such technologies, their potential to leapfrog surveillance over currently available, conventional technologies in use today and early steps that health systems could take towards preparing to adopt them

Sleep and 24-h activity rhythms in relation to cortisol change after a very low-dose of dexamethasone

The hypothalamic-pituitary-adrenal (HPA) axis plays an important role in sleep. Nevertheless, the association of sleep and its 24-h organization with negative feedback control of the HPA axis has received limited attention in population-based studies. We explored this association in 493 mid

Phenotyping UK Electronic Health Records from 15 Million Individuals for Precision Medicine: He CALIBER Resource

Electronic health records (EHR) are increasingly being used for observational research at scale. In the UK, we have established the CALIBER research resource which utilizes national primary and hospital EHR data sources and enables researchers to create and validate longitudinal disease phenotypes at scale. In this work, we will describe the core components of the resource and provide results from three exemplar research studies on high-resolution epidemiology, disease risk prediction and subtype discovery which demonstrate both the opportunities and challenges of using EHR for research

Risk Factors for Development of Rhegmatogenous Retinal Detachment in Patients with Uveitis

Purpose: To describe risk factors for development of rhegmatogenous retinal detachment (RRD) in patients with uveitis. Methods: We performed a retrospective review of 411 consecutive human immunodeficiency virus-negative patients with uveitis (571 affected eyes) and report on prevalence, risk factors and visual outcomes of patients with RRD. Results: Prevalence of RRD was 7% of all patients with uveitis. Multivariate analysis revealed that posterior uveitis and panuveitis were associated with RRD (P = 0.001). Strong association between RRD development and infectious uveitis was also observed (P = 0.009). Acute retinal necrosis (ARN) was firmly associated with RRD development (P = 0.016). Although anatomical success was obtained, functional outcome was poor. Poor visual outcomes at 6-month and 1-year follow-up were associated with initial VA < counting fingers (P = 0.05, P = 0.044). Conclusions: Prevalence of RRD in uveitis was 7% and development of RRD was encountered in posterior and panuveitis. Infectious uveitis (specifically ARN) formed a high risk for RRD

The very low-dose dexamethasone suppression test in the general population: A cross-sectional study

Determinants of the hypothalamic-pituitary-adrenal (HPA) axis functioning are increasingly explored in population-based studies. However, functional tests measuring the negative feedback of the HPA axis cannot easily be implemented into large observational studies. Furthermore, high doses of dexamethasone often completely suppress the HPA axis in healthy persons. This study aimed to detect the effects of the health, lifestyle and sociodemographic factors, psychiatric problems and cognitive functions on the negative feedback of the HPA axis using a very low-dose (0.25 mg) dexamethasone suppression test (DST). We evaluated the associations of several determinants with the saliva cortisol concentrations after dexamethasone intake in a confounder-adjusted model also corrected for baseline saliva cortisol concentrations in the Rotterdam Study, a large population-based study (N = 1822). We found that female sex, low income, lack of exercise, instrumental disability and smoking were all independently associated with stronger suppression of the HPA axis. Even though there were no linear associations between psychiatric measures and cortisol suppression, we found that depressive symptoms and anxiety disorders were more common in persons with non-suppression of cortisol. Conversely, psychotropic medication use was related to enhanced suppression of cortisol after DST. In this large study, we found that female gender, low socioeconomic status and poor health were all related to suppression of the HPA axis. Non-linear associations were detected between the suppression of the HPA axis and common psychiatric disorders in community-dwelling persons

Methods for Enhancing the Reproducibility of Observational Research Using Electronic Health Records: Preliminary Findings From the Caliber Resource

The ability of external investigators to reproduce published scientific findings is critical for the evaluation and validation of health research by the wider community. However, a substantial proportion of health research using electronic health records, data collected and generated during routine clinical care, potentially cannot reproduced. With the complexity, volume and variety of electronic health records made available for research steadily increasing, it is critical to ensure that findings from such data are reproducible and replicable by researchers. In this paper, we present some preliminary findings on how a series of methods and tools utilized in adjunct scientific disciplines can be used to enhance the reproducibility of research using electronic health records

Anxiety disorders and salivary cortisol levels in older adults: A population-based study

Context: The hypothalamic-pituitary-adrenal (HPA) axis is one of the body's main systems that controls response to stress. It acts through the hormone cortisol. While the dysregulation of cortisol has been associated with anxiety disorders, the evidence is inconsistent. Moreover, only a few small studies have assessed this relationship in older adults. Objective: To determine whether in adults aged 65 years and over there is a difference in daily cortisol pattern between those with and without an anxiety disorder. Methods: The study population comprised 1788 older adults from a population-based cohort. The Munich version of the Composite International Diagnostic Interview was used to diagnose anxiety disorders (generalized anxiety disorder, social phobia, specific phobia, agoraphobia and panic disorder). The cortisol awakening response and total cortisol secretion over the day were calculated from cortisol levels in four saliva samples taken over the course of one day (at awakening, 30. min after awakening, at 1700. h, at bedtime). Results: Older adults with an anxiety disorder (n=145, median duration since first symptoms 41 years) had a lower cortisol awakening response (p=0.02) than those without such a disorder (n=1643). This association was most prominent in those with generalized anxiety disorder (p=0.008), but was not associated with the extent of chronicity of anxiety disorders. Conclusion: Older adults from the general population with long-lasting anxiety disorders had a lower cortisol awakening response than those without. This is consistent with the notion that chronic anxiety may result in downregulation of HPA-axis activity. Longitudinal studies are needed to confirm this mechanism

Surveillance and Epidemiology of Drug Resistant Infections Consortium (SEDRIC): Supporting the transition from strategy to action.

In recognition of the central importance of surveillance and epidemiology in the control of antimicrobial resistance and the need to strengthen surveillance at all levels, Wellcome has brought together a new international expert group SEDRIC (Surveillance and Epidemiology of Drug Resistant Infections Consortium). SEDRIC aims to advance and transform the ways of tracking, sharing and analysing rates of infection and drug resistance, burden of disease, information on antibiotic use, opportunities for preventative measures such as vaccines, and contamination of the environment. SEDRIC will strengthen the availability of information needed to monitor and track risks, including an evaluation of access to, and utility of data generated by pharma and research activities, and will support the translation of surveillance data into interventions, changes in policy and more effective practices. Ways of working will include the provision of independent scientific analysis, advocacy and expert advice to groups, such as the Wellcome Drug Resistant Infection Priority Programme. A priority for SEDRIC's first Working Group is to review mechanisms to strengthen the generation, collection, collation and dissemination of high quality data, together with the need for creativity in the use of existing data and proxy measures, and linking to existing in-country networking infrastructure. SEDRIC will also promote the translation of technological innovations into public health solutions

Burkholderia pseudomallei Is Genetically Diverse in Agricultural Land in Northeast Thailand

Burkholderia pseudomallei is the cause of melioidosis, a serious human infection most commonly diagnosed in southeast Asia and northern Australia. The organism lives in the soil in a specific geographical distribution and infection results from bacterial inoculation, inhalation or ingestion. The purpose of this study was to define the distribution and genetic diversity of B. pseudomallei in agricultural land where most human infections probably occur. We performed soil sampling and culture for the presence of B. pseudomallei in 100 equally spaced points within a rice paddy in northeast Thailand, and undertook genotyping of primary culture plate colonies from 11 sampling points. We identified 7 different genotypes, with relatively limited overlap between different sampling points. Two samples contained more than one B. pseudomallei genotype, in which a numerically dominant genotype coexisted with one or more additional genotypes present as a minority population. We conclude that genetic diversity and structuring of B. pseudomallei exists despite the effects of flooding and the physical and chemical processes associated with farming. These findings inform future efforts to define B. pseudomallei in the environment, and should be considered during the design stage of studies comparing B. pseudomallei isolated from the environment and from patients with invasive disease