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Obstructive sleep apnea (OSA) is a common sleep-related breathing disorder. In animal models, OSA has been shown to alter the gut microbiota; however, little is known about such effects in humans. Here, we used respiratory polygraphy data from 3,570 individuals aged 50–64 from the Swedish CardioPulmonary bioImage Study (SCAPIS) and deep shotgun metagenomics to identify OSA-associated gut microbiota features. We found that OSA-related hypoxia parameters were associated with 128 bacterial species, including positive associations with Blautia obeum and Collinsela aerofacines. The latter was also associated with increased systolic blood pressure. Further, the cumulative time in hypoxia was associated with nine gut microbiota metabolic pathways, including propionate production from lactate, a biomarker of hypoxia. In conclusion, in this first large-scale study on gut microbiota alterations in OSA, we found that OSA-related hypoxia is associated with specific microbiota features. Our findings can direct future research on microbiota-mediated health effects of OSA.

Obesity is associated with adverse health outcomes, but the metabolic effects have not yet been fully elucidated. We aimed to investigate the association between adiposity with circulating metabolites and to address causality with Mendelian randomization (MR). Metabolomics data was generated by non-targeted ultra-performance liquid-chromatography coupled to time-of-flight mass-spectrometry in plasma and serum from three population-based Swedish cohorts: ULSAM (N=1,135), PIVUS (N=970), and TwinGene (N=2,059). We assessed associations between general adiposity measured as body mass index (BMI) and central body fat distribution measured as waist-to-hip ratio adjusted for BMI (WHRadjBMI) with 210 annotated metabolites. We employed MR analysis to assess causal effects. Lastly, we attempted to replicate the MR findings in the KORA and TwinsUK cohorts (N=7,373), the CHARGE consortium (N=8,631), the Framingham Heart Study (N=2,076) and the DIRECT consortium (N=3,029). BMI was associated with 77 metabolites, while WHRadjBMI was associated with 11 and 3 metabolites in women and men, respectively. The MR analyses in the Swedish cohorts suggested a causal association (p-value P-16:0) as well as with increased creatine levels. The replication effort provided support for a causal association of adiposity on reduced levels of arachidonic acid (p-value 0.03). Adiposity is associated with variation of large parts of the circulating metabolome, however causality needs further investigation in well-powered cohorts.

Objective To investigate whether dog and cat owners and their pets share a risk of developing diabetes. Design Cohort study. Setting Register based longitudinal study, Sweden. Participants 208 980 owner-dog pairs and 123 566 owner-cat pairs identified during a baseline assessment period (1 January 2004 to 31 December 2006). Main outcome measures Type 2 diabetes events in dog and cat owners and diabetes events in their pets, including date of diagnosis during the follow-up period (1 January 2007 to 31 December 2012). Owners with type 2 diabetes were identified by combining information from the National Patient Register, the Cause of Death Register, and the Swedish Prescribed Drug Register. Information on diabetes in the pets was extracted from veterinary care insurance data. Multi-state models were used to assess the hazard ratios with 95% confidence intervals and to adjust for possible shared risk factors, including personal and socioeconomic circumstances. Results The incidence of type 2 diabetes during follow-up was 7.7 cases per 1000 person years at risk in dog owners and 7.9 cases per 1000 person years at risk in cat owners. The incidence of diabetes in the pets was 1.3 cases per 1000 dog years at risk and 2.2 cases per 1000 cat years at risk. The crude hazard ratio for type 2 diabetes in owners of a dog with diabetes compared with owners of a dog without diabetes was 1.38 (95% confidence interval 1.10 to 1.74), with a multivariable adjusted hazard ratio of 1.32 (1.04 to 1.68). Having an owner with type 2 diabetes was associated with an increased hazard of diabetes in the dog (crude hazard ratio 1.28, 1.01 to 1.63), which was attenuated after adjusting for owner’s age, with the confidence interval crossing the null (1.11, 0.87 to 1.42). No association was found between type 2 diabetes in cat owners and diabetes in their cats (crude hazard ratio 0.99, 0.74 to 1.34, and 1.00, 0.78 to 1.28, respectively). Conclusions Data indicated that owners of a dog with diabetes were more likely to develop type 2 diabetes during follow-up than owners of a dog without diabetes. It is possible that dogs with diabetes could serve as a sentinel for shared diabetogenic health behaviours and environmental exposures.

Adverse childhood experiences (ACEs) have consistently been associated with elevated risk of multiple adverse health outcomes, yet their contribution to coping ability and psychiatric resilience in adulthood is unclear. Participants were 19,613 women in the Icelandic Stress- And-Gene-Analysis cohort with complete data on 13 ACEs measured with the ACE-International Questionnaire. Self-reported coping ability was measured with the Connor-Davidson Resilience Scale and psychiatric resilience was operationalized as absence of psychiatric morbidity. Compared to women with 0 ACEs, women with ≥ 5 ACEs had 33% lower prevalence of high coping ability (PR=0.67, 95% CI 0.60,0.74) and 56% lower prevalence of high psychiatric resilience (PR=0.44; 95% CI 0.41,0.48). Specific ACEs including emotional neglect, bullying, sexual abuse and mental illness of household member were consistently associated with reduced adult resilience. We observed only slightly attenuated associations after controlling for adult socioeconomic factors and social support in adulthood, indicating that adult resilience may be largely determined in childhood.

BackgroundThe response of the Swedish authorities to the COVID-19 pandemic was less restrictive than in most countries during the first year, with infection and death rates substantially higher than in neighbouring Nordic countries. Because access to PCR testing was limited during the first wave (February to June 2020) and regional data were reported with delay, adequate monitoring of community disease spread was hampered. The app-based COVID Symptom Study was launched in Sweden to disseminate real-time estimates of disease spread and to collect prospective data for research. The aim of this study was to describe the research project, develop models for estimation of COVID-19 prevalence and to evaluate it for prediction of hospital admissions for COVID-19. MethodsWe enrolled 143 531 study participants ([≥]18 years) throughout Sweden, who contributed 10{middle dot}6 million daily symptom reports between April 29, 2020 and February 10, 2021. Data from 19 161 self-reported PCR tests were used to create a symptom-based algorithm to estimate daily prevalence of symptomatic COVID-19. The prediction model was validated using external datasets. We further utilized the model estimates to forecast subsequent new hospital admissions. FindingsA prediction model for symptomatic COVID-19 based on 17 symptoms, age, and sex yielded an area under the ROC curve of 0{middle dot}78 (95% CI 0{middle dot}74-0{middle dot}83) in an external validation dataset of 943 PCR-tested symptomatic individuals. App-based surveillance proved particularly useful for predicting hospital trends in times of insufficient testing capacity and registration delays. During the first wave, our prediction model estimates demonstrated a lower mean error (0{middle dot}38 average new daily hospitalizations per 100 000 inhabitants per week (95% CI 0{middle dot}32, 0{middle dot}45)) for subsequent hospitalizations in the ten most populated counties, than a model based on confirmed case data (0{middle dot}72 (0{middle dot}64, 0{middle dot}81)). The model further correctly identified on average three out of five counties (95% CI 2{middle dot}3, 3{middle dot}7) with the highest rates of hospitalizations the following week during the first wave and four out of five (3{middle dot}0, 4{middle dot}6) during the second wave. InterpretationThe experience of the COVID Symptom Study highlights the important role citizens can play in real-time monitoring of infectious diseases, and how app-based data collection may be used for data-driven rapid responses to public health challenges. FundingSwedish Heart-Lung Foundation (20190470, 20140776), Swedish Research Council (EXODIAB, 2009-1039; 2014-03529), European Commission (ERC-2015-CoG - 681742 NASCENT), and Swedish Foundation for Strategic Research (LUDC-IRC, 15-0067) to MG or PF. European Research Council Starting Grant (801965) to TF. NO was financially supported by the Knut and Alice Wallenberg Foundation as part of the National Bioinformatics Infrastructure Sweden at SciLifeLab. ATC was supported in this work through the Massachusetts Consortium on Pathogen Readiness (MassCPR). ZOE Limited provided in-kind support for all aspects of building, running and supporting the app and service to all users worldwide. Support for this study for KCL researchers was provided by the National Institute for Health Research (NIHR)-funded Biomedical Research Centre based at Guys and St Thomas (GSTT) NHS Foundation Trust. This work was supported by the UK Research and Innovation London Medical Imaging & Artificial Intelligence Centre for Value-Based Healthcare. Investigators also received support from the Wellcome Trust, Medical Research Council (MRC), British Heart Foundation (BHF), Alzheimers Society, European Union, NIHR, COVID-19 Driver Relief Fund (CDRF) and the NIHR-funded BioResource, Clinical Research Facility and Biomedical Research Centre (BRC) based at GSTT NHS Foundation Trust in partnership with KCL. ZOE Limited developed the app for data collection as a not-for-profit endeavour. None of the funding entities had any role in study design, data analysis, data interpretation, or the writing of this manuscript.

Early reports raised concern that use of non-steroidal anti-inflammatory drugs (NSAIDs) may increase risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease (COVID-19). Users of the COVID Symptom Study smartphone application reported use of aspirin and other NSAIDs between March 24 and May 8, 2020. Users were queried daily about symptoms, COVID-19 testing, and healthcare seeking behavior. Cox proportional hazards regression was used to determine the risk of COVID-19 among according to aspirin or non-aspirin NSAID users. Among 2,736,091 individuals in the U.S., U.K., and Sweden, we documented 8,966 incident reports of a positive COVID-19 test over 60,817,043 person-days of follow-up. Compared to non-users and after stratifying by age, sex, country, day of study entry, and race/ethnicity, non-aspirin NSAID use was associated with a modest risk for testing COVID-19 positive (HR 1.23 [1.09, 1.32]), but no significant association was observed among aspirin users (HR 1.13 [0.92, 1.38]). After adjustment for lifestyle factors, comorbidities and baseline symptoms, any NSAID use was not associated with risk (HR 1.02 [0.94, 1.10]). Results were similar for those seeking healthcare for COVID-19 and were not substantially different according to lifestyle and sociodemographic factors or after accounting for propensity to receive testing. Our results do not support an association of NSAID use, including aspirin, with COVID-19 infection. Previous reports of a potential association may be due to higher rates of comorbidities or use of NSAIDs to treat symptoms associated with COVID-19.One Sentence SummaryNSAID use is not associated with COVID-19 risk.

BackgroundDiagnostic testing is essential for disease surveillance and test-trace-isolate efforts. Here, we aimed to investigate if residential area sociodemographic characteristics and test accessibility were associated with COVID-19 testing rates.MethodsWe included information on 421 542 patient-initiated COVID-19 PCR tests from Uppsala County in Sweden from 24 June, 2020 to 9 February, 2022. Using Poisson regression analyses, we investigated whether the Care Need Index (CNI; median 1.0, IQR 0.8, 1.4), a composite measure of sociodemographic factors used in Sweden to allocate primary healthcare resources, was associated with aggregated COVID-19 daily testing rates after adjustments for community transmission. We further assessed if distance to the nearest testing station influenced testing. Lastly, we performed a difference-in-difference analysis of the opening of a testing station targeting a disadvantaged neighbourhood.ResultsWe observed that CNI, i.e. primary healthcare need, was negatively associated with COVID-19 testing rates in inhabitants aged 5-69 years. More pronounced differences were noted across younger age groups and in Uppsala City, with test rate ratios in children (5-14 years) ranging from 0.56 (95% CI 0.47-0.66) to 0.88 (95% CI 0.81-0.95) across the three pandemic waves. Longer distance to testing station was linked to lower testing rates, foremost in less densely populated areas. Furthermore, the opening of the targeted testing station was associated with increased testing, including twice as high testing rates in individuals aged 70-105, supporting an intervention effect.ConclusionsEnsuring accessible testing across all residential areas constitutes a promising tool to decrease differences and inequalities in testing.

Early life determinants of the oral microbiota have not been thoroughly elucidated. We studied the association of birth and early childhood characteristics with oral microbiota composition using 16 S ribosomal RNA (rRNA) gene sequencing in a population-based Swedish cohort of 59 children sampled at 6, 12 and 24 months of age. Repeated-measurement regression models adjusted for potential confounders confirmed and expanded previous knowledge about the profound shift of oral microbiota composition in early life. These alterations included increased alpha diversity, decreased beta diversity and alteration of bacterial composition with changes in relative abundance of 14 of the 20 most common operational taxonomic units (OTUs). We also found that birth characteristics, breastfeeding and antibiotic use were associated with overall phyla distribution and/or with the relative abundance of specific OTUs. Further, we detected a novel link between morning salivary cortisol level, a physiological marker of neuroendocrine activity and stress, and overall phyla distribution as well as with decreased abundance of the most common OTU mapped to the Streptococcaceae family. In conclusion, a major part of the maturation of the oral microbiome occurs during the first two years of life, and this development may be influenced by early life circumstances.

Although childhood traumatic experiences are recognized as important determinants for adolescent psychiatric health in general, our objective was to explore the specific influence of childhood bereavement on the stress resilience development trajectory.In this national register-based cohort study, we identified 407,639 men born in Sweden between 1973 and 1983, who underwent compulsory military enlistment examinations in late adolescence, including measures of psychological stress resilience. We defined exposure as loss of a first-degree family member in childhood, and estimated relative risk ratios (RRRs) for reduced (moderate or low), compared with high, stress resilience with 95% confidence intervals (CIs) using multinomial logistic regression.Loss of a parent or sibling in childhood conferred a 49% increased risk of subsequent low stress resilience (RRR, 1.49, 95% CI, 1.41-1.57) and an 8% increased risk of moderate stress resilience (RRR, 1.08, 95% CI, 1.03-1.13) in late adolescence. There was also a graded increase in risk with increasing age at loss; teenagers were at higher risk for low resilience (RRR, 1.64, 95% CI, 1.52-1.77) than children aged 7-12 (RRR, 1.47, 95% CI, 1.34-1.61) and ≤6 years (RRR, 1.16 95% CI, 1.02-1.32). The excess risk was observed for all causes of death, including suicide and unexpected deaths as well as deaths due to other illnesses. The associations remained after exclusion of parents with a history of hospitalization for psychiatric diagnoses.The long-term consequences of childhood bereavement may include lower stress resilience in late adolescence.

Background: A parental cancer diagnosis is a stressful life event, potentially leading to increased risks of mental and physical problems among children. This study aimed to investigate the associations of parental cancer with IQ, stress resilience, and physical fitness of the affected men during early adulthood. Materials and methods: In this Swedish population-based study, we included 465,249 men born during 1973–1983 who underwent the military conscription examination around the age of 18 years. We identified cancer diagnoses among the parents of these men from the Cancer Register. IQ, stress resilience, and physical fitness of the men were assessed at the time of conscription and categorized into three levels: low, moderate, and high (reference category). We used multinomial logistic regression to assess the studied associations. Results: Overall, parental cancer was associated with higher risks of low stress resilience (relative risk ratio [RRR]: 1.09 [95% confidence interval (CI) 1.04–1.15]) and low physical fitness (RRR: 1.12 [95% CI 1.05–1.19]). Stronger associations were observed for parental cancer with a poor expected prognosis (low stress resilience: RRR: 1.59 [95% CI 1.31–1.94]; low physical fitness: RRR: 1.45 [95% CI 1.14–1.85]) and for parental death after cancer diagnosis (low stress resilience: RRR: 1.29 [95% CI 1.16–1.43]; low physical fitness: RRR: 1.40 [95% CI 1.23–1.59]). Although there was no overall association between parental cancer and IQ, parental death after cancer diagnosis was associated with a higher risk of low IQ (RRR: 1.11 [95% CI 1.01–1.24]). Conclusion: Parental cancer, particularly severe and fatal type, is associated with higher risks of low stress resilience and low physical fitness among men during early adulthood. Men who experienced parental death after cancer diagnosis also have a higher risk of low IQ., This study was supported by the Swedish Research Council for Health, Working Life and Welfare (grant number: 2012- 0498), and the Swedish Cancer Society (grant number: CAN 2014/417). Dr Fang was supported by the Karolinska Institutet (Senior Researcher Award and the Strategic Research Program in Epidemiology). Dr Chen was supported by the China Scholarship Council (no. 201206100002).

BackgroundWhile compromised stress resilience constitutes a recognised risk factor for somatic and psychiatric disease development in general, the knowledge about how individual variation in vulnerability to stress may specifically influence the long-term risks of disadvantageous health behaviours is limited.MethodsIn this Swedish cohort study, we aimed to investigate the association between stress resilience in late adolescence and adult use of addictive substances. We included 9381 men with information on psychological stress resilience measured during military conscription examinations, who later responded to an extensive health survey (mean age 34.0±7.2 years) including detailed information on substance use. We modelled continuous outcomes using linear regression, binary outcomes with logistic regression and other categorical outcomes with multinomial logistic regression.ResultsWe found that low stress resilience in adolescence conferred increased risks of all studied measures of addictive behaviour. After adjusting for childhood socioeconomic information, low stress resilience was associated with adult current regular smoking (relative risk ratio: 5.85, 95% CI 4.32 to 7.93), higher nicotine dependence scores (beta: 0.76, 95% CI 0.29 to 1.23), hazardous use of alcohol (>14 alcoholic drink-equivalents per week, OR: 1.72, 95% CI 1.37 to 2.16), DSM-IV criteria for alcohol dependence (OR: 1.74, 95% CI 1.35 to 2.25), and drug use (OR: 1.77, 95% CI 1.51 to 2.08). The results remained largely unchanged after further adjustments for adult educational attainment and occupation as well as for additional conscription covariates.ConclusionLow stress resilience in late adolescence appears to be associated with an increased risk of disadvantageous and addictive health behaviours in adulthood.

BackgroundStress resilience is recognised as a determinant of both psychiatric and somatic health, but the potential link between stress resilience and cancer development has not been explored.MethodsIn this nationwide cohort study, we examined the association between stress resilience in adolescence and subsequent cancer risk. We identified a cohort of 284 257 Swedish men, born 1952–1956, who underwent compulsory military enlistment examinations including measures of psychological stress resilience (median age 18 years). The resulting score was categorised as low, moderate and high stress resilience. Individuals diagnosed with cancer during the follow-up time were identified through data linkage to the Swedish Cancer Register.ResultsLowest stress resilience, compared with the highest, was associated with increased risks of liver (HR: 4.73, 95% CI 2.73 to 8.19) and lung (HR: 2.75, 95% CI 2.02 to 3.74) cancer after adjusting for markers of socioeconomic circumstances in childhood (p for trend ConclusionWe conclude that adolescent stress resilience, plausibly by influencing behavioural choices and social patterns, constitutes an important determinant of adult cancer occurrence. Increased awareness of long-term consequences in susceptible individuals may help direct future efforts to reduce cancer burden in adults.

While early-life exposure to stress has been associated with subsequent psychiatric and cardiovascular morbidity, little is known regarding its potential role in cancer development. We hypothesized that severe emotional stress, such as the loss of a parent through death during childhood, may increase the risk of cancer in early life.Based on the Swedish Multi-Generation Register, we identified a cohort of 4,219,691 individuals who had both parents identifiable in the same register and followed the cohort from birth to the age of 40 years between 1961 and 2006. Through information retrieved from the Swedish Causes of Death and Cancer Registers, we ascertained death among the parents and cancer diagnosis among the cohort individuals. We used Poisson regression to calculate the relative risks (RRs) and 95 % confidence intervals (CIs).Parental death was not associated with total cancer risk. However, parental death during childhood was associated with a higher risk of human papillomavirus (HPV) infection-related cancers (RR 1.4; 95 % CI 1.2-1.7), and loss during early adulthood (18 years) entailed a higher risk of cancers of the stomach (RR 1.8; 95 % CI 1.3-2.6), lung (RR 1.7; 95 % CI 1.1-2.4), rectum (RR 1.4; 95 % CI 1.0-2.0), and breast (RR 1.1; 95 % CI 1.0-1.3). A significant association was observed for pancreatic cancer for both loss during childhood (RR 2.6; 95 % CI 1.6-4.2) and afterward (RR 2.8; 95 % CI 1.9-4.3).Our results suggest that severe psychological stress in early life may be associated with premature development of certain malignancies, particularly cancers related to smoking and HPV infection.