Social position and functional somatic disorders: The DanFunD study.

BACKGROUND AND AIM: It is generally accepted that functional somatic disorders (FSDs) are a product of biological, psychological, and social factors. Social position might be part of this complex, but the literature on this issue is currently heterogeneous and inconsistent. The aim of the present study was - in a population-based cohort - to test the hypothesis that lower social position would be associated with higher a risk of FSD. METHOD: The association between social position and FSD was examined in a cross-sectional study with various measures of social position (education as measured by vocational training; employment; cohabitation; subjective social status) and delimitations of FSD (irritable bowel syndrome, chronic fatigue syndrome, fibromyalgia, bodily distress syndrome, and symptom profiles). The associations were analyzed using logistic regressions to calculate odds ratios and 95% confidence intervals. Each social measure was analyzed independently and was adjusted for age and sex. RESULTS: Lower levels of vocational training, being unemployed, and living alone were associated with higher risk of FSD, regardless of the FSD delimitation. There was also a significant negative association between subjective evaluated social status and FSD. The associations remained after multiple adjustments, and seemed to be strongest for the more severe FSD-types. CONCLUSIONS: Lower social position is associated with higher risk of FSD, especially the more severe FSD delimitations, which might constitute an especially vulnerable group. However, the mechanisms behind the relations remain unknown.

Normative values of short-term heart rate variability in a cross-sectional study of a Danish population. The DanFunD study.

AIMS: The autonomic nervous system includes parasympathetic and sympathetic components that monitor and regulate most of the bodily functions and play a central role in the physiology and homeostasis of the human body. Heart rate variability is a non-invasive tool for quantification of rhythmic fluctuations in heart rate that reflects the function of the autonomic nervous system. The study aims to describe the heart rate variability distribution in the general population, stratified in sex and age groups, which is currently insufficiently described. METHODS: A cross-sectional population-based study recruited participants in 10 municipalities in the western part of the greater Copenhagen area in Denmark, including 6891 men and women aged 18-72 years (participation rate was 29.5%). Short-term heart rate variability measures were obtained and related to age and gender. RESULTS: Both time and frequency domain measures showed a huge variation in the different sex and age groups. Women had a higher median heart rate than men, and the association with age was U-shaped. Measures indicating a predominance of the parasympathetic component in relation to the sympathetic component were more frequent in women and younger age groups. CONCLUSIONS: Both sex and age influence the heart rate variability in this adult Danish population. Therefore, our age- and sex-related reference values of heart rate variability in the time and frequency domain should be used in further epidemiological and clinical research.

Irritable bowel symptoms, use of healthcare, costs, sickness and disability pension benefits: A long-term population-based study.

Objectives: Irritable bowel syndrome (IBS) is associated with increased healthcare use and work absenteeism. We aimed to investigate long-term use of healthcare services and social benefits across IBS symptom groups. Additionally, we estimated excess healthcare costs. Methods: A longitudinal population-based study comprising two 5-year follow-up studies: The Danish part of the Multinational Monitoring of Trends and Determinants in Cardiovascular Disease (Dan-MONICA) 1 (1982-1987) and Inter99 (1999-2004) recruited from the western part of Copenhagen County. The total study population (n = 7278) was divided into symptom groups according to degree of IBS definition fulfillment at baseline and/or 5-year follow-up and was followed until 31 December 2013 in Danish central registries. Poisson regression was used for the analyses adjusting for age, sex, length of education, comorbidity, cohort membership and mental vulnerability. Results: IBS symptom groups compared to no IBS symptoms were associated with an increased number of contacts with primary and secondary healthcare, as well as weeks on sickness and disability benefits. Accounting for mental vulnerability decreased the estimates and all but two associations between IBS symptom groups and outcomes remained statistically significant. The two associations that became insignificant were contacts with psychiatric hospitals and weeks on disability pension. The excess unadjusted healthcare costs for IBS were 680 Euros per year and the overall association between symptom groups and total healthcare costs were statistically significant. Conclusions: IBS symptoms influence the long-term use and costs of healthcare, as well as the use of social benefits in the general population. Mental vulnerability explained some, but not all, of the use of healthcare and social benefits.

Aberrant intestinal microbiota in individuals with prediabetes.

AIMS/HYPOTHESIS: Individuals with type 2 diabetes have aberrant intestinal microbiota. However, recent studies suggest that metformin alters the composition and functional potential of gut microbiota, thereby interfering with the diabetes-related microbial signatures. We tested whether specific gut microbiota profiles are associated with prediabetes (defined as fasting plasma glucose of 6.1-7.0 mmol/l or HbA1c of 42-48 mmol/mol [6.0-6.5%]) and a range of clinical biomarkers of poor metabolic health. METHODS: In the present case-control study, we analysed the gut microbiota of 134 Danish adults with prediabetes, overweight, insulin resistance, dyslipidaemia and low-grade inflammation and 134 age- and sex-matched individuals with normal glucose regulation. RESULTS: We found that five bacterial genera and 36 operational taxonomic units (OTUs) were differentially abundant between individuals with prediabetes and those with normal glucose regulation. At the genus level, the abundance of Clostridium was decreased (mean log2 fold change -0.64 (SEM 0.23), p adj = 0.0497), whereas the abundances of Dorea, [Ruminococcus], Sutterella and Streptococcus were increased (mean log2 fold change 0.51 (SEM 0.12), p adj = 5 × 10-4; 0.51 (SEM 0.11), p adj = 1 × 10-4; 0.60 (SEM 0.21), p adj = 0.0497; and 0.92 (SEM 0.21), p adj = 4 × 10-4, respectively). The two OTUs that differed the most were a member of the order Clostridiales (OTU 146564) and Akkermansia muciniphila, which both displayed lower abundance among individuals with prediabetes (mean log2 fold change -1.74 (SEM 0.41), p adj = 2 × 10-3 and -1.65 (SEM 0.34), p adj = 4 × 10-4, respectively). Faecal transfer from donors with prediabetes or screen-detected, drug-naive type 2 diabetes to germfree Swiss Webster or conventional C57BL/6 J mice did not induce impaired glucose regulation in recipient mice. CONCLUSIONS/INTERPRETATION: Collectively, our data show that individuals with prediabetes have aberrant intestinal microbiota characterised by a decreased abundance of the genus Clostridium and the mucin-degrading bacterium A. muciniphila. Our findings are comparable to observations in overt chronic diseases characterised by low-grade inflammation.

Fluctuation of functional somatic disorders in a population-based cohort. The DanFunD study.

BACKGROUND: Evidence of incidence of functional somatic disorders (FSD) is hampered by unclear delimitations of the conditions and little is known about the possible interchangeability between syndromes. Further, knowledge on remission and persistence of FSD in the general population is limited. We aimed to assess the natural course of various FSD over 5 years in the general population. METHODS: A follow-up study (Danish Study of Functional Disorders-DanFunD) was conducted in a random sample of the general population comprising 5,738 participants aged 18-76 years at baseline. Both at baseline and five-year follow-up, participants filled in validated questionnaires on symptoms to delimitate two approaches of FSD, the bodily distress syndrome (BDS) and four functional somatic syndromes (FSS): irritable bowel (IB), chronic fatigue (CF), chronic widespread pain (CWP), and multiple chemical sensitivity (MCS). RESULTS: Both BDS and FSS showed a five-year incidence around 11%. Incidence of the individual FSS varied from 0.8% (MCS) to 5.7% (CF). BDS and FSS showed a remission proportion close to 50%. We found a high degree of interchangeability between each FSS varying from 15.0% to 23.4%. CONCLUSION: We identified a marked fluctuation pattern of FSD during a five-year period, with a high degree of interchangeability between each FSS. The study stresses the importance of large population-based cohorts with transparent delimitation of FSD in future research to understand these complex conditions.

The gut microbiota in multiple sclerosis varies with disease activity.

BACKGROUND: Multiple sclerosis is a chronic immune-mediated disease of the brain and spinal cord resulting in physical and cognitive impairment in young adults. It is hypothesized that a disrupted bacterial and viral gut microbiota is a part of the pathogenesis mediating disease impact through an altered gut microbiota-brain axis. The aim of this study is to explore the characteristics of gut microbiota in multiple sclerosis and to associate it with disease variables, as the etiology of the disease remains only partially known. METHODS: Here, in a case-control setting involving 148 Danish cases with multiple sclerosis and 148 matched healthy control subjects, we performed shotgun sequencing of fecal microbial DNA and associated bacterial and viral microbiota findings with plasma cytokines, blood cell gene expression profiles, and disease activity. RESULTS: We found 61 bacterial species that were differentially abundant when comparing all multiple sclerosis cases with healthy controls, among which 31 species were enriched in cases. A cluster of inflammation markers composed of blood leukocytes, CRP, and blood cell gene expression of IL17A and IL6 was positively associated with a cluster of multiple sclerosis-related species. Bacterial species that were more abundant in cases with disease-active treatment-naïve multiple sclerosis were positively linked to a group of plasma cytokines including IL-22, IL-17A, IFN-ß, IL-33, and TNF-α. The bacterial species richness of treatment-naïve multiple sclerosis cases was associated with number of relapses over a follow-up period of 2 years. However, in non-disease-active cases, we identified two bacterial species, Faecalibacterium prausnitzii and Gordonibacter urolithinfaciens, whose absolute abundance was enriched. These bacteria are known to produce anti-inflammatory metabolites including butyrate and urolithin. In addition, cases with multiple sclerosis had a higher viral species diversity and a higher abundance of Caudovirales bacteriophages. CONCLUSIONS: Considerable aberrations are present in the gut microbiota of patients with multiple sclerosis that are directly associated with blood biomarkers of inflammation, and in treatment-naïve cases bacterial richness is positively associated with disease activity. Yet, the finding of two symbiotic bacterial species in non-disease-active cases that produce favorable immune-modulating compounds provides a rationale for testing these bacteria as adjunct therapeutics in future clinical trials.

Development and Validation of the Weighted Index for Childhood Adverse Conditions (WICAC).

BACKGROUND: Adverse experiences in childhood are a major public health concern, promoting social inequality in health through biopsychosocial mechanisms. So far, no known measures comprehend the complexity and variations of severity of adverse events. This study aims to develop and validate a new index: the Weighted Index for Childhood Adverse Conditions (WICAC). METHODS: The population consists of 7493 randomly invited men and women aged 18-72 years. Data were collected in 2012-2015 as part of the Danish Study of Functional Disorders (DanFunD). Content and construct validation of the WICAC was performed with the hypothesis testing of multiple biopsychosocial outcomes: cardiovascular disease, cancer, poor health, back pain, BMI, obesity, anxiety, depression, low vitality, subjective social status, lower education, smoking, and alcohol consumption. Data were analysed with binominal and linear regression models with risk ratios (RR) and mean differences (MD). RESULTS: Content validation is fitting for WICAC. The strongest associations observed were for most severe adversity: Poor Health RR = 2.16 (1.19-2.91), Anxiety RR = 3.32 (2.32-4.74), Heavy Drinking RR = 4.09 (1.85-9.04), and Subjective Social Status MD = -0.481 (-0.721-(-0.241)). Similar results were found for the remaining outcomes. Discriminative validation was undecided. CONCLUSIONS: WICAC is an adequate instrument for measuring cumulative adverse life events in childhood and adolescence for research purposes.

Insulin Resistance Is Associated with Multiple Chemical Sensitivity in a Danish Population-Based Study-DanFunD.

Multiple chemical sensitivity (MCS) is a multisystem syndrome, and limited knowledge of its pathophysiology exists. Based on the population-based Danish cohort DanFunD, this study investigated metabolic health in people with MCS compared to individuals who did not have MCS. From 9656 cohort participants aged 18-76 years old, 1.95% were categorized as MCS individuals with comorbid functional somatic disorders (MCS +FSD, n = 188), and 1.13% were categorized as MCS without functional somatic disorders (MCS ÷FSD, n = 109). MCS was characterized based on three criteria: the experience of symptoms upon exposure to common odors and airborne chemicals, symptoms related the central nervous systems and others organ symptoms, and significant impact on every day, social, and occupational life. The remaining study population without MCS or any other functional somatic disorders were regarded as controls. We used adjusted multiple linear regression with link-function to evaluate the associations between lipid and glucose metabolism markers and MCS. We also tested the odds ratio of metabolic syndrome in MCS. Results did not point to statistically significant associations between lipid biomarkers or metabolic syndrome and both MCS groups compared to the controls. We found that MCS individuals may be more insulin resistant and that MCS ÷ FSD may have an impaired glucose metabolism when compared to controls.

Gene expression profiling in persons with multiple chemical sensitivity before and after a controlled n-butanol exposure session.

OBJECTIVES: To investigate the pathophysiological pathways leading to symptoms elicitation in multiple chemical sensitivity (MCS) by comparing gene expression in MCS participants and healthy controls before and after a chemical exposure optimised to cause symptoms among MCS participants.The first hypothesis was that unexposed and symptom-free MCS participants have similar gene expression patterns to controls and a second hypothesis that MCS participants can be separated from controls based on differential gene expression upon a controlled n-butanol exposure. DESIGN: Participants were exposed to 3.7 ppm n-butanol while seated in a windowed exposure chamber for 60 min. A total of 26 genes involved in biochemical pathways found in the literature have been proposed to play a role in the pathogenesis of MCS and other functional somatic syndromes were selected. Expression levels were compared between MCS and controls before, within 15 min after being exposed to and 4 hours after the exposure. SETTINGS: Participants suffering from MCS and healthy controls were recruited through advertisement at public places and in a local newspaper. PARTICIPANTS: 36 participants who considered themselves sensitive were prescreened for eligibility. 18 sensitive persons fulfilling the criteria for MCS were enrolled together with 18 healthy controls. OUTCOME MEASURES: 17 genes showed sufficient transcriptional level for analysis. Group comparisons were conducted for each gene at the 3 times points and for the computed area under the curve (AUC) expression levels. RESULTS: MCS participants and controls displayed similar gene expression levels both at baseline and after the exposure and the computed AUC values were likewise comparable between the 2 groups. The intragroup variation in expression levels among MCS participants was noticeably greater than the controls. CONCLUSIONS: MCS participants and controls have similar gene expression levels at baseline and it was not possible to separate MCS participants from controls based on gene expression measured after the exposure.

Chemical intolerance.

Chemical intolerance (CI) is a term used to describe a condition in which the sufferer experiences a complex array of recurrent unspecific symptoms attributed to low-level chemical exposure that most people regard as unproblematic. Severe CI constitutes the distinguishing feature of multiple chemical sensitivity (MCS). The symptoms reported by CI subjects are manifold, involving symptoms from multiple organs systems. In severe cases of CI, the condition can cause considerable life-style limitations with severe social, occupational and economic consequences. As no diagnostic tools for CI are available, the presence of the condition can only be established in accordance to criteria definitions. Numerous modes of action have been suggested to explain CI, with the most commonly discussed theories involving the immune system, central nervous system, olfactory and respiratory systems as well as altered metabolic capacity, behavioral conditioning and emotional regulation. However, in spite of more than 50 years of research, there is still a great deal of uncertainties regarding the event(s) and underlying mechanism( s) behind symptom elicitation. As a result, patients are often misdiagnosed or offered health care solutions with limited or no effect, and they experience being met with mistrust and doubt by health care professionals, the social care system and by friends and relatives. Evidence-based treatment options are currently unavailable, however, a person-centered care model based on a multidisciplinary treatment approach and individualized care plans have shown promising results. With this in mind, further research studies and health care solutions should be based on a multifactorial and interdisciplinary approach.