Establishing a causal link between social relationships and health using the Bradford Hill Guidelines.
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ABSTRACT:
SUBMITTER: Howick J
PROVIDER: S-EPMC6527915 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundStudies report an elevated risk of maltreatment in children with attention deficit/hyperactivity disorder (ADHD), and elevated levels of ADHD in people who suffered childhood maltreatment (CM). However, the direction(s) of causality between CM and ADHD remain unclear-does ADHD create a context for CM, does CM cause ADHD, or both?ObjectiveThis study systematically reviews and qualitatively synthesizes the research evidence relating to this question using Bradford-Hill criteria for establishing causality-strength, temporality, dose-response and plausibility.MethodsWe conducted a systematic review, following PRISMA guidelines, of prospective longitudinal studies examining both CM and ADHD. We then used Bradford-Hill criteria to assess the quality of evidence for a causal link between CM and ADHD.ResultsAll 11 included studies demonstrated an association between CM and ADHD. Seven included evidence for temporality: five suggesting that CM precedes ADHD in the lifespan; two suggesting ADHD precedes CM. Four studies demonstrated a dose response relationship in which greater CM exposure was associated with elevated risk of ADHD. Studies presented a range of plausible mechanisms, including CM causing ADHD through biological programming, versus ADHD causing CM through parental stress.ConclusionsThe high quality prospective longitudinal studies reviewed confirm the association between ADHD and CM, but present conflicting evidence about the direction of causality and mechanisms underpinning this association. To better understand the complex interplay between CM and ADHD, more studies using new research designs will be required that can partition effects by type of CM and account for bidirectional effects and other complexities.
| S-EPMC10694545 | biostudies-literature
Project description:ObjectiveThe aim of this study was to systematically evaluate the direction of any potential causal effect between sleep and adiposity traits.MethodsTwo-sample Mendelian randomization was used to assess the association of genetically predicted sleep traits with adiposity and vice versa. Using data from UK Biobank and 23andMe, the sleep traits explored were morning preference (chronotype; N = 697,828), insomnia (N = 1,331,010), sleep duration (N = 446,118), napping (N = 452,633), and daytime sleepiness (N = 452,071). Using data from the Genetic Investigation of ANthropometric Traits (GIANT) and Early Growth Genetics (EGG) consortia, the adiposity traits explored were adult BMI, hip circumference (HC), waist circumference (WC), waist-hip ratio (WHR; N = 322,154), and childhood BMI (N = 35,668).ResultsThis study found evidence that insomnia symptoms increased mean WC, BMI, and WHR (difference in means, WC = 0.39 SD [95% CI: 0.13-0.64], BMI = 0.47 SD [95% CI: 0.22-0.73], and WHR = 0.34 SD [95% CI: 0.16-0.52]). Napping increased mean WHR (0.23 SD [95% CI: 0.08-0.39]). Higher HC, WC, and adult BMI increased odds of daytime sleepiness (HC = 0.02 SD [95% CI: 0.01-0.04], WC = 0.04 SD [95% CI: 0.01-0.06], and BMI 0.02 SD [95% CI: 0.00-0.04]). This study also found that higher mean childhood BMI resulted in lower odds of napping (-0.01 SD [95% CI: 0.02-0.00]).ConclusionsThe effects of insomnia on adiposity and of adiposity on daytime sleepiness suggest that poor sleep and weight gain may contribute to a feedback loop that could be detrimental to overall health.
| S-EPMC10946465 | biostudies-literature
Project description:Recent work suggests that olfactory dysfunction is a strong predictor of five-year mortality in older adults. Based on past work showing: 1) that olfactory dysfunction impairs social functioning and 2) that social ties are linked with mortality, the current work explored whether impairments in social life mediated the relationship between olfactory dysfunction and mortality. Additionally, based on work showing gender differences in the social consequences of olfactory dysfunction, gender was assessed as a potential moderator of this association. Social network size mediated the olfactory-mortality link for females. To probe what feature of social networks was driving this effect, we investigated two subcomponents of social life: emotional closeness (e.g., perceived social support, loneliness) and physical closeness (e.g., physical contact, in-person socializing with others). Physical closeness significantly mediated the olfactory-mortality link for females, even after controlling for social network size. Emotional closeness did not mediate this link. Possible mechanisms underlying this relationship are discussed.
| S-EPMC5955501 | biostudies-literature
Project description:ObjectiveWe aimed to investigate the causal relationships between social isolation and osteoarthritis.MethodsPublicly available genome-wide association study (GWAS) summary statistics of social isolation and osteoarthritis in European population were obtained from the Neale lab Consortium and the Medical Research Council-Integrative Epidemiology Unit (MRC-IEU) consortium, respectively. Single nucleotide polymorphisms (SNPs) associated with the traits were identified by P < 5×10-8 and linkage disequilibrium r2 < 0.1. Three Mendelian randomization (MR) methods including the inverse-variance weighted (IVW) method, weighted median estimator, and MR-Egger regression were used to assess the potential causal effect of social isolation on osteoarthritis and the potential causal effect of osteoarthritis on social isolation. Leave-one-out analysis and test of directional horizontal pleiotropy via MR-Egger regression were performed as sensitivity analyses.ResultsWhen evaluating the causal effect of social isolation on osteoarthritis, five SNPs (rs12364432, rs13291079, rs2352075, rs4958586, rs599550) significantly associated with social isolation were studied as instruments, and social isolation was found to be causally associated with increased risk of osteoarthritis (odds ratio [OR] 1.197 (95% confidence interval (CI) 1.096-1.308) estimated by the IVW method). When evaluating the causal effect of osteoarthritis on social isolation, six SNPs (rs10405617, rs12133235, rs13107325, rs2290573, rs3771501, rs75621460) significantly associated with osteoarthritis were studied as instruments but no causal effect of osteoarthritis on social isolation was found (OR 1.104 (95% CI 0.887-1.375) estimated by the IVW method). Consistent causal relationships were observed when estimated by the weighted median estimator and MR-Egger regression. Leave-one-out analysis and test of directional horizontal pleiotropy suggested the robustness of the above findings.ConclusionSocial isolation is causally associated with osteoarthritis, and further work is needed to investigate the potential mechanisms.
| S-EPMC8523904 | biostudies-literature
Project description:We present a unique case study report of a male individual with a history of mild nonischaemic cardiomyopathy, with no ventricular ectopy, that at the age of 76 years sustained multiple concussions (i.e., mild traumatic brain injury) within a week of each other. Concussion symptoms included cognitive difficulties, "not feeling well," lethargy, fatigue, and signs of depression. He was later medically diagnosed with postconcussion syndrome. The patient, WJT, was referred for cardiac and neurological assessment. Structural neuroimaging of the brain (MRI) was unremarkable, but electrocardiography (ECG) assessments using a 24-hour Holter monitor revealed significant incidence of ventricular ectopy (9.4%; 9,350/99,836 beats) over a period of 5-6 months after injury and then a further increase in ventricular ectopy to 18% (15,968/88,189 beats) during the subsequent 3 months. The patient was then prescribed Amiodarone 200?mg, and his ventricular ectopy and concussion symptoms completely resolved simultaneously within days. To the authors' knowledge, our study is the first to show a direct link between observable and documented cardiac dysregulation and concussion symptomology. Our study has important implications for both cardiac patients and the patients that sustain a concussion, and if medically managed with appropriate pharmacological intervention, it can reverse ventricular ectopy and concussion symptomology. More research is warranted to investigate the mechanisms for this dramatic and remarkable change in cardiac and cerebral functions and to further explore the brain-heart interaction and the intricate autonomic interaction that exists between the extrinsic and intracardiac nervous systems.
| S-EPMC7292985 | biostudies-literature
Project description:Pairs of active neurons frequently fire action potentials or "spikes" nearly synchronously (i.e., within 5 ms of each other). This spike synchrony may occur by chance, based solely on the neurons' fluctuating firing patterns, or it may occur too frequently to be explicable by chance alone. When spike synchrony above chances levels is present, it may subserve computation for a specific cognitive process, or it could be an irrelevant byproduct of such computation. Either way, spike synchrony is a feature of neural data that should be explained. A point process regression framework has been developed previously for this purpose, using generalized linear models (GLMs). In this framework, the observed number of synchronous spikes is compared to the number predicted by chance under varying assumptions about the factors that affect each of the individual neuron's firing-rate functions. An important possible source of spike synchrony is network-wide oscillations, which may provide an essential mechanism of network information flow. To establish the statistical link between spike synchrony and network-wide oscillations, we have integrated oscillatory field potentials into our point process regression framework. We first extended a previously-published model of spike-field association and showed that we could recover phase relationships between oscillatory field potentials and firing rates. We then used this new framework to demonstrate the statistical relationship between oscillatory field potentials and spike synchrony in: 1) simulated neurons, 2) in vitro recordings of hippocampal CA1 pyramidal cells, and 3) in vivo recordings of neocortical V4 neurons. Our results provide a rigorous method for establishing a statistical link between network oscillations and neural synchrony.
| S-EPMC4605746 | biostudies-literature
Project description:Two literatures have explored some of the effects intimate relationships can have on physical and mental health outcomes. Research investigating health through the lens of attachment theory has demonstrated that more anxiously attached individuals in particular consistently report poorer health. Separate research on perceived social support (e.g., partner or spousal support) suggests that higher support has salutary influences on various health outcomes. Little to no research, however, has explored the interaction of attachment anxiety and perceived social support on health outcomes. The present study examined the attachment-health link and the moderating role of perceived social support in a community sample of married couples. Results revealed that more anxious persons reported poorer overall physical and mental health, more bodily pain, more medical symptoms, and impaired daily functioning, even after controlling for age, relationship length, neuroticism, and marital quality. Additionally, perceived social support interacted with attachment anxiety to influence health; more anxious individuals' health was poorer even when perceived social support was high, whereas less anxious individuals' health benefited from high support. Possible mechanisms underlying these findings and the importance of considering attachment anxiety in future studies of poor health in adulthood are discussed.
| S-EPMC3988242 | biostudies-literature
Project description:BackgroundThe possibility that onchocerciasis may cause epilepsy has been suggested for a long time, but thus far, an etiological link has not been universally accepted. The objective of this review is to critically appraise the relationship between Onchocerca volvulus and epilepsy and subsequently apply the Bradford Hill criteria to further evaluate the likelihood of a causal association.MethodsPubMed and gray literature published until September 15, 2020, were searched and findings from original research were synthesized. Adherence to the 9 Bradford Hill criteria in the context of onchocerciasis and epilepsy was determined to assess whether the criteria are met to strengthen the evidence base for a causal link between infection with O. volvulus and epilepsy, including the nodding syndrome.ResultsOnchocerciasis as a risk factor for epilepsy meets the following Bradford Hill criteria for causality: strength of the association, consistency, temporality, and biological gradient. There is weaker evidence supporting causality based on the specificity, plausibility, coherence, and analogy criteria. There is little experimental evidence. Considering the Bradford Hill criteria, available data suggest that under certain conditions (high microfilarial load, timing of infection, and perhaps genetic predisposition), onchocerciasis is likely to cause epilepsy including nodding and Nakalanga syndromes.ConclusionApplying the Bradford Hill criteria suggests consistent epidemiological evidence that O. volvulus infection is a trigger of epilepsy. However, the pathophysiological mechanisms responsible for seizure induction still need to be elucidated.
| S-EPMC7790236 | biostudies-literature
Project description:Aims/hypothesisExcess adiposity is differentially associated with increased risk of cardiometabolic disease in men and women, according to observational studies. Causal inference studies largely assume a linear relationship between BMI and cardiometabolic outcomes, which may not be the case. In this study, we investigated the shapes of the causal relationships between BMI and cardiometabolic diseases and risk factors. We further investigated sex differences within the causal framework.MethodsTo assess causal relationships between BMI and the outcomes, we used two-stage least-squares Mendelian randomisation (MR), with a polygenic risk score for BMI as the instrumental variable. To elucidate the shapes of the causal relationships, we used a non-linear MR fractional polynomial method, and used piecewise MR to investigate threshold relationships and confirm the shapes.ResultsBMI was associated with type 2 diabetes (OR 3.10; 95% CI 2.73, 3.53), hypertension (OR 1.53; 95% CI 1.44, 1.62) and coronary artery disease (OR 1.20; 95% CI 1.08, 1.33), but not chronic kidney disease (OR 1.08; 95% CI 0.67, 1.72) or stroke (OR 1.08; 95% CI 0.92, 1.28). The data suggest that these relationships are non-linear. For cardiometabolic risk factors, BMI was positively associated with glucose, HbA1c, triacylglycerol levels and both systolic and diastolic BP. BMI had an inverse causal relationship with total cholesterol, LDL-cholesterol and HDL-cholesterol. The data suggest a non-linear causal relationship between BMI and BP and other biomarkers (p<0.001) except lipoprotein A. The piecewise MR results were consistent with the fractional polynomial results. The causal effect of BMI on coronary artery disease, total cholesterol and LDL-cholesterol was different in men and women, but this sex difference was only significant for LDL-cholesterol after controlling for multiple testing (p<0.001). Further, the causal effect of BMI on coronary artery disease varied by menopause status in women.Conclusions/interpretationWe describe the shapes of causal effects of BMI on cardiometabolic diseases and risk factors, and report sex differences in the causal effects of BMI on LDL-cholesterol. We found evidence of non-linearity in the causal effect of BMI on diseases and risk factor biomarkers. Reducing excess adiposity is highly beneficial for health, but there is greater need to consider biological sex in the management of adiposity.
| S-EPMC9807546 | biostudies-literature
Project description:BackgroundEthnic minorities in Northern Thailand, often referred to as Hill Tribes, are considered an ideal model to study the different genetic impact of sex-specific migration rates expected in matrilocal (women remain in their natal villages after the marriage and men move to their wife's village) and patrilocal societies (the opposite is true). Previous studies identified such differences, but little is known about the possible interaction with another cultural factor that may potentially affect genetic diversity, i.e. linguistic differences. In addition, Hill Tribes started to migrate to Thailand in the last centuries from different Northern areas, but the history of these migrations, the level of genetic legacy with their places of origin, and the possible confounding effects related to this migration history in the patterns of genetic diversity, have not been analysed yet. Using both original and published data on the Hill Tribes and several other Asian populations, we focused on all these aspects.ResultsGenetic variation within population at mtDNA is lower in matrilocal, compared to patrilocal, tribes. The opposite is true for Y-chromosome microsatellites within the Sino-Tibetan linguistic family, but Hmong-Mien speaking patrilocal groups have a genetic diversity very similar to the matrilocal samples. Population divergence ranges between 5% and 14% at mtDNA sequences, and between 5% and 36% at Y-chromosomes STRs, and follows the sex-specific differences expected in patrilocal and matrilocal tribes. On the average, about 2 men and 14 women, and 4 men and 4 women, are exchanged in patrilocal and matrilocal tribes every generation, respectively. Most of the Hill Tribes in Thailand seem to preserve a genetic legacy with their likely geographic origin, with children adoption probably affecting this pattern in one tribe.ConclusionOverall, the sex specific genetic signature of different postmarital habits of residence in the Hill Tribes is robust. However, specific perturbations related to linguistic differences, population specific traits, and the complex migratory history of these groups, can be identified. Additional studies in different populations are needed, especially to obtain more precise estimates of the migration parameters.
| S-EPMC1963483 | biostudies-literature