Understanding How Much TV is Too Much: A Nonlinear Analysis of the Association Between Television Viewing Time and Adverse Health Outcomes

Intergenerational care and rural childhood obesity in the digital era: Based on screen exposure perspective

Background

Rural Chinese children are experiencing increasing obesity rates, yet studies often neglect the impact of IT and screen media growth on obesity risks in the context of intergenerational care, leading to incomplete strategies for the digital era.

Methods

By comprehensively utilizing the data on rural children aged 6-17 from the China Family Panel Studies (CFPS) and the China Health and Nutrition Survey (CHNS), this study aims to test the logical chain and specific mechanisms regarding "intergenerational care - screen exposure - rural childhood obesity". We employ the Propensity Score Matching (PSM) and Generalized Propensity Score Matching (GPSM) methods to respectively address the self-selection biases associated with inter-generational care and children's screen exposure behaviors.

Results

1) Intergenerational care significantly increases screen exposure among rural children. 2) Gender bias increases the risk of screen exposure for rural boys under intergenerational care. 3) Children with higher screen exposure levels are more affected by intergenerational care, which further undermines parental supervision. 4) Children's screen exposure leads to increased sedentary time and higher probability of purchasing unhealthy foods, thereby exacerbating obesity. This process is facilitated by enhancing preferences for snacks, fast food, and beverages, and weakening preferences for physical activity. 5) GPSM analysis indicates that children's screen exposure has an inverted "U"-shaped impact on unhealthy dietary preferences and a "U"-shaped impact on activity preferences. It results in a nonlinear positive impact of screen exposure on obesity. This study reveals a positive association between screen exposure and obesity, offering new insights into how intergenerational care in the digital era may elevate obesity prevalence through excessive screen time for rural children.

Leisure Screen Time and Food Consumption among Brazilian Adults

BACKGROUND

Screen time, involving activities like watching television (TV), and using tablets, mobile phones, and computers (electronic devices), is associated with the consumption of unhealthy foods. This study aimed to analyze the association between prolonged leisure screen time and healthy and unhealthy food consumption indicators among Brazilian adults (≥18 years).

METHODS

Data from the National Health Survey (NHS), conducted in 2019 (n = 88,531), were used. Prolonged leisure screen time (screen time ≥ 3 h/day) was analyzed in three dimensions: watching TV; use of electronic devices; and total screen time (TV and electronic devices). Food consumption was analyzed in two dimensions: healthy (in natura and minimally processed foods) and unhealthy (ultra-processed foods). Poisson regression models were used to calculate prevalence ratios (crude and adjusted (PRa)) by sociodemographic factors (sex, age, schooling, income, area of residence, and race/color) and health factors (weight status, self-rated health, and presence of noncommunicable disease), to assess the association between prolonged screen time and food consumption indicators.

RESULTS

Among Brazilian adults, the prevalence of prolonged screen time was 21.8% for TV and 22.2% for other electronic devices for leisure. The highest frequency of watching TV for a prolonged time was observed among women, older adults, and those with a lower income and schooling. Prolonged use of electronic devices was more common among young adults and those with intermediate schooling and income. Prolonged screen time was associated with an unhealthy diet, due both to the higher consumption of unhealthy foods (PRa = 1.35 for TV, PRa = 1.21 for electronic devices, and PRa = 1.32 for both types) and the lower consumption of healthy foods (PRa = 0.88 for TV, PRa = 0.86 for electronic devices, and PRa = 0.86 for both).

CONCLUSIONS

Prolonged screen time was negatively associated with the consumption of healthy foods and favored the consumption of unhealthy foods among Brazilian adults.

Associations between Recreational Screen Time and Brain Health in Middle-Aged and Older Adults: A Large Prospective Cohort Study

OBJECTIVES

To investigate the associations of recreational screen time with risks of brain-related disorders (dementia, stroke, and Parkinson's disease) and neuroimaging features.

DESIGN

Prospective cohort study.

SETTING AND PARTICIPANTS

A total of 407,792 participants from the UK Biobank who were free of dementia, stroke, or Parkinson's disease at enrollment (2006-2010).

METHODS

TV viewing and time spent using the computer were self-reported at baseline. Among a subsample of 40,692 participants, neuroimaging features were measured by magnetic resonance imaging in 2014. Data were analyzed using Cox proportional hazard models, restricted cubic spline models, and general linear regression models.

RESULTS

During a median follow-up of 12.6 years, 5227 incident dementia, 6822 stroke, and 2308 Parkinson's disease cases were identified. Compared with TV viewing >0-1 h/day, watching TV ≥5 h/day was associated with higher risks of dementia [hazard ratio (HR), 1.44; 95% confidence interval (CI), 1.28-1.62], stroke (HR, 1.12; 95% CI, 1.01-1.25), and Parkinson's disease (HR, 1.28; 95% CI, 1.06-1.54). Moreover, we observed inverse associations between TV viewing time and both gray matter volume and hippocampus volume (Ptrend <.001). However, we did not observe the significant associations between discretional computer use and brain-related disorders or neuroimaging features.

CONCLUSIONS AND IMPLICATIONS

Our findings suggest that high TV viewing time is associated with increased risk of various brain-related disorders, highlighting recreational TV viewing could have an important impact on brain-related health.

The influence of socioeconomic status on the association between unhealthy lifestyle factors and adverse health outcomes: a systematic review

Background

Combinations of lifestyle factors (LFs) and socioeconomic status (SES) are independently associated with cardiovascular disease (CVD), cancer, and mortality. Less advantaged SES groups may be disproportionately vulnerable to unhealthy LFs but interactions between LFs and SES remain poorly understood. This review aimed to synthesise the available evidence for whether and how SES modifies associations between combinations of LFs and adverse health outcomes.

Methods

Systematic review of studies that examine associations between combinations of >3 LFs (eg.smoking/physical activity/diet) and health outcomes and report data on SES (eg.income/education/poverty-index) influences on associations. Databases (PubMed/EMBASE/CINAHL), references, forward citations, and grey-literature were searched from inception to December 2021. Eligibility criteria were analyses of prospective adult cohorts that examined all-cause mortality or CVD/cancer mortality/incidence.

Results

Six studies (n=42,467-399,537; 46.5-56.8 years old; 54.6-59.3% women) of five cohorts were included. All examined all-cause mortality; three assessed CVD/cancer outcomes. Four studies observed multiplicative interactions between LFs and SES, but in opposing directions. Two studies tested for additive interactions; interactions were observed in one cohort (UK Biobank) and not in another (National Health and Nutrition Examination Survey (NHANES)). All-cause mortality HRs (95% confidence intervals) for unhealthy LFs (versus healthy LFs) from the most advantaged SES groups ranged from 0.68 (0.32-1.45) to 4.17 (2.27-7.69). Equivalent estimates from the least advantaged ranged from 1.30 (1.13-1.50) to 4.00 (2.22-7.14). In 19 analyses (including sensitivity analyses) of joint associations between LFs, SES, and all-cause mortality, highest all-cause mortality was observed in the unhealthiest LF-least advantaged suggesting an additive effect.

Conclusions

Limited and heterogenous literature suggests that the influence of SES on associations between combinations of unhealthy LFs and adverse health could be additive but remains unclear. Additional prospective analyses would help clarify whether SES modifies associations between combinations of unhealthy LFs and health outcomes.

Registration

Protocol is registered with PROSPERO (CRD42020172588;25 June 2020).

Identifying the causal relationship between sedentary behavior and heart failure: Insights from a Mendelian randomization study and mediation analysis

BACKGROUND

Observational studies have revealed that a lack of physical exercise may be linked to a higher risk of heart failure (HF). Here, the causal relationship between sedentary behavior (SB) and HF was investigated using Mendelian randomization (MR).

HYPOTHESIS

SB was considered as an important risk factor of HF.

METHODS

Single nucleotide polymorphisms with a genome-wide statistical significance threshold of <5 × 10-8 among the SB-proxied phenotypes (TV screen time, computer use, and driving) from genome-wide association study (GWAS) datasets were identified as instrumental variables (IVs). The MR study was performed using the inverse-variance weighting (IVW) model as a primary standard to evaluate causal relationships. Simultaneously, MR-Egger regression, weighted median, and maximum likelihood models were used as supplements. Sensitivity analysis, consisting of a heterogeneity and horizontal pleiotropy test, was performed using Cochran's Q, MR-Egger intercept, and MR-PRESSO tests to ensure the reliability of conclusions.

RESULTS

The IVW model results showed that increased TV screen time correlated with a higher genetic susceptibility for HF in both HF-associated GWAS datasets, which was also supported by weighted median and maximum likelihood model results. The odds ratios with 95% confidence intervals were 1.418 (1.182-1.700) and 1.486 (1.136-1.943), respectively. Although the results of Cochran's Q test indicated certain heterogeneity among the IVs. The MR-Egger intercept and MR-PRESSO tests suggested no horizontal pleiotropy and verified the reliability of the conclusion.

CONCLUSIONS

This MR study identified that increased TV screen time may predispose individuals to the development of HF.

The causal effects of leisure screen time on irritable bowel syndrome risk from a Mendelian randomization study

Associations between leisure sedentary behavior (especially leisure screen time, LST) and irritable bowel syndrome (IBS) have been reported, but causality is unclear. Here, the two-sample Mendelian randomization was performed to investigate the causal association between LST and IBS. Two recently published genome-wide association studies (GWASs) including a total of 1,190,502 people from Europe were used as our data source. Inverse variance weighting (OR = 1.120, 95% CI 1.029-1.219) and weighted median (OR = 1.112, 95% CI 1.000-1.236) analyses revealed a causal effect between LST and IBS. There was no evidence of pleiotropy in the sensitive analysis (MR-Egger, p = 0.139). After removing potentially confounding single nucleotide polymorphisms (SNPs), similar results were found using inverse variance weighting (OR = 1.131, 95% CI 1.025-1.248) and weighted median (OR = 1.151, 95% CI 1.020-1.299), as well as in the validation analyses using inverse variance weighting (OR = 1.287, 95% CI 0.996-1.662). This study provided support for a possible causal relationship between leisure screen time and IBS.

Analysis of the 24-h activity cycle: An illustration examining the association with cognitive function in the Adult Changes in Thought study

The 24-h activity cycle (24HAC) is a new paradigm for studying activity behaviors in relation to health outcomes. This approach inherently captures the interrelatedness of the daily time spent in physical activity (PA), sedentary behavior (SB), and sleep. We describe three popular approaches for modeling outcome associations with the 24HAC exposure. We apply these approaches to assess an association with a cognitive outcome in a cohort of older adults, discuss statistical challenges, and provide guidance on interpretation and selecting an appropriate approach. We compare the use of the isotemporal substitution model (ISM), compositional data analysis (CoDA), and latent profile analysis (LPA) to analyze 24HAC. We illustrate each method by exploring cross-sectional associations with cognition in 1,034 older adults (Mean age = 77; Age range = 65-100; 55.8% female; 90% White) who were part of the Adult Changes in Thought (ACT) Activity Monitoring (ACT-AM) sub-study. PA and SB were assessed with thigh-worn activPAL accelerometers for 7-days. For each method, we fit a multivariable regression model to examine the cross-sectional association between the 24HAC and Cognitive Abilities Screening Instrument item response theory (CASI-IRT) score, adjusting for baseline characteristics. We highlight differences in assumptions and the scientific questions addressable by each approach. ISM is easiest to apply and interpret; however, the typical ISM assumes a linear association. CoDA uses an isometric log-ratio transformation to directly model the compositional exposure but can be more challenging to apply and interpret. LPA can serve as an exploratory analysis tool to classify individuals into groups with similar time-use patterns. Inference on associations of latent profiles with health outcomes need to account for the uncertainty of the LPA classifications, which is often ignored. Analyses using the three methods did not suggest that less time spent on SB and more in PA was associated with better cognitive function. The three standard analytical approaches for 24HAC each have advantages and limitations, and selection of the most appropriate method should be guided by the scientific questions of interest and applicability of each model's assumptions. Further research is needed into the health implications of the distinct 24HAC patterns identified in this cohort.

Do all vegetarians have a lower cardiovascular risk? A prospective study

BACKGROUND

Vegetarian diets are heterogeneous and their health benefits may vary. This study aimed to compare the cardiovascular risk among vegetarian diets that meet existing health guidelines, those that do not, and diets that include red meat.

METHODS

391,124 participants (55.5% women) from the UK Biobank prospective population-based study were included. Using data from a food frequency questionnaire, participants were categorised into lacto-vegetarian or meat-eaters. Then, both groups were dichotomised into a healthier and less healthy group using an unweighted score based on current UK guidelines. Ischaemic heart disease (IHD) and myocardial infarction (MI) incidence - both separately and as a composite of major adverse cardiovascular events (MACE) - were the outcomes included. Associations between types of diets and health outcomes were investigated using Cox proportional hazard models adjusted for confounder factors.

RESULTS

After a median follow-up of 10.4 years, there were 40,048 MACE. When the analyses were adjusted for prevalent morbidity and lifestyle factors, people who followed healthier vegetarian and meat-eater diets had 18% (95% CI: 0.73 to 0.92) and 5% (95% CI: 0.93 to 0.97) lower risk of MACE than less healthy meat-eaters. Similar patterns were identified for the individual outcomes, with the strongest association observed for MI. The cardiovaculasr risk among less healthy vegetarians and less healthy meat-eaters were not significnatly different.

CONCLUSIONS

Vegetarian diets are heterogeneous and the cardiovascular risk varied accordingly. Future studies should consider the overall dietary patterns of vegetarians rather than just based on meat consumption. Guidelines advocating a plant-based diet need to stress the importance of overall diet quality in addition to the reduction of meat.

Genetic liability to sedentary behavior in relation to myocardial infarction and heart failure: A mendelian randomization study

BACKGROUND AND AIMS

Observational studies have indicated that sedentary behavior is associated with myocardial infarction (MI), heart failure (HF), and atrial fibrillation (AF). Nevertheless, whether these associations are causal remain controversial, due to confounding factors (e.g., physical activity) and reverse causality.

METHODS AND RESULTS

Instrumental variables were obtained from the largest genome-wide association studies of sedentary behavior (408,815 individuals) to date. We obtained summary statistics of MI from the CARDIoGRAMplusC4D consortium (171,875 individuals), HF from the HERMES Consortium (977,323 individuals), and AF from the Atrial Fibrillation Consortium (588,190 individuals). The inverse-variance weighted method was applied to obtain Mendelian randomization (MR) estimates, and other statistical methods were conducted in the sensitivity analyses. The main analyses were repeated using data from the FinnGen study. Multivariable MR analysis and mediation analysis were performed to evaluate the role of physical activity and other confounders. Genetically determined television watching was associated with MI (odds ratio [OR], 1.38; 95% CI, 1.19-1.59; p = 1.9 × 10^-5) and HF (OR, 1.23; 95%CI, 1.09-1.38; p = 7.0 × 10^-4) but not AF. The main results kept robust in most sensitivity analyses. The effect of sedentary behavior on MI and HF was partly mediated by body mass index (BMI). No consistent evidence was found for the causal effect of computer use and driving on MI, HF, or AF.

CONCLUSIONS

Genetic liability to prolonged television watching is associated with higher risks of MI and HF. Interventions for reducing television watching time, such as public education and awareness campaigns, should be further investigated.

Associations of sedentary time and physical activity with adverse health conditions: Outcome-wide analyses using isotemporal substitution model

Background

As one of the most common lifestyles today, sedentary behaviour is a risk factor for many health conditions. To inform potential behavioural guideline development, we aimed to estimate the theoretical effects of replacing sedentary behaviour with different intensity of physical activity on risks of 45 common non-communicable diseases (NCDs).

Methods

A total of 360,047 participants (aged 37-73 years) in the UK Biobank free of the 45 common non-communicable diseases (NCDs) were included. Information on sedentary time (sum of television watching, computer using and driving behaviour) and physical activity (measured by International Physical Activity Questionnaire questionnaire) were collected by self-reported at baseline. Participants were followed up for 45 NCDs diagnosis according to the ICD-10 code using linkage to national health records until 2020. Isotemporal substitution models were used to investigate substituting sedentary time with light physical activity (LPA), moderate physical activity (MPA) and vigorous physical activity (VPA) after adjusting for potential confounders.

Finding

Participants who reported > 6 h/day compared with ≤ 2 h/day sedentary time had higher risks of 12 (26.7%) of 45 NCDs, including ischemic heart disease, diabetes, chronic obstructive pulmonary disease, asthma, chronic kidney disease, chronic liver disease, thyroid disorder, depression, migraine, gout, rheumatoid arthritis and diverticular disease. Theoretically, replacing sedentary time with equivalent LPA, MPA and VPA was associated with risk reductions in 4, 6 and 10 types of NCDs, respectively. Among long sedentary time (> 6 h/day), replacing 1 h/day sedentary time with equivalent VPA showed stronger associations with 5 NCDs (diabetes, depression, chronic liver disease, diverticular disease and sleep disorder), with a larger risk reduction of 11%-31%.

Interpretation

Sedentary time is associated with multiple adverse health conditions, replacing sedentary time with any equivalent amounts of VPA than LPA and MPA could be associated with risk reductions of more types of NCDs.

Funding

National Natural Science Foundation of China.

Analysis of sedentariness in women from a gender and equity perspective

ABSTRACTThis cross-sectional study aimed to analyse the social and gender-related factors influencing sedentariness in women, including occupation and family size (FS). We included women aged 45-70 years participating in the Breast Cancer Screening Programme of the Valencia Region (BCSP-VR) between November 2018 and October 2019 (n = 121,988). The response variable was sedentariness measured by sitting time in hours/day (h/day) (<3 h/day and ≥3 h/day). The explanatory variables were age, educational level, country of origin, living alone, childcare responsibilities, FS, disability, body mass index (BMI) and smoking status. Logistic regression models were adjusted for the whole sample and were stratified by occupation and FS. The variables that increased the odds of sedentariness were age ≥65 years (OR = 1.28; CI = 1.20-1.36), high educational level (OR = 1.39; CI = 1.31-1.47), non-manual occupation (OR = 2.38; CI = 2.27-2.48), living alone (OR = 1.11; CI = 1.05-1.17), disability (OR = 1.37; CI = 1.20-1.56) and BMI ≥ 30 (OR = 1.33; CI = 1.28-1.38). The variables decreasing the odds were large (OR = 0.90; CI = 0.87-0.96) and medium FS (OR = 0.93; CI = 0.90-0.97). Older age, high educational level and high BMI conferred a higher odd of sedentary lifestyle, independently of occupation and FS with statistical differences. Protective factors were childcare responsibilities in non-working women (OR = 0.86; CI = 0.74-0.99), large FS in women with manual occupations (OR = 0.88; CI = 0.80-0.97) and medium FS in housewives (OR = 0.91; CI = 0.86-0.97). This study identified social and gender-related inequalities in the factors influencing sedentariness, which were related to the type of occupation and FS.

Adverse associations of sedentary behavior with cancer incidence and all-cause mortality: A prospective cohort study

BACKGROUND

Inconsistent results have been reported in developed countries for relationships between sedentary behavior and cancer incidence and mortality, and evidence from the Chinese population is scarce. This study aimed to investigate such relationships in large Chinese population-based prospective cohorts and to explore the joint effect and interaction of sedentary behavior and moderate-to-vigorous physical activity (MVPA) on these relationships.

METHODS

We included 95,319 Chinese adults without cancer from 3 large cohorts and assessed their sedentary behavior and physical activity with a unified questionnaire. Cancer incidence and mortality were confirmed by interviewing participants or their proxies and checking hospital records and death certificates. Hazard ratios (HRs) and 95% confidence intervals (95%CIs) for cancer and mortality were estimated using Cox proportional hazards regression models.

RESULTS

During 559,002 person-years of follow-up, 2388 cancer events, 1571 cancer deaths, and 4562 all-cause deaths were recorded. Sedentary behavior was associated with increased risk of developing cancer and deaths in a dose-response manner. The multivariable-adjusted HRs (95%CIs) were the following: HR = 1.16, 95%CI: 1.01‒1.33; HR = 1.24, 95%CI: 1.04‒1.48; and HR = 1.15, 95%CI: 1.04‒1.28 for cancer incidence, cancer mortality, and all-cause mortality, respectively, for those having ≥10 h/day of sedentary time compared with those having <6 h/day of sedentary time. Sedentary populations (≥10 h/day) developed cancer or died 4.09 years and 2.79 years earlier, respectively, at the index age of 50 years. Failure to achieve the recommended level of MVPA may further aggravate the adverse associations, with the highest cancer and mortality risks being observed among participants with both ≥10 h/day of sedentary time and <150 min/week of MVPA. Limitations of this study include the fact that physical activity information was obtained via questionnaire instead of objective measurement and that there were insufficient incident cases for the analysis of associations between sedentary behavior and site-specific cancers.

CONCLUSION

Sedentary behavior was associated with an increased risk of cancer and all-cause mortality among Chinese adults, especially for those with ≥10 h/day of sedentary time. It is necessary to reduce sedentary time, in addition to increasing MVPA levels, for the prevention of cancer and premature death.

Fitness Level Differences between Students in Kosovo and Montenegro

Geographical, cultural, and socio-economic factors create a different lifestyle. Accordingly, the aim of this research was to identify the differences in anthropometric and fitness characteristics among adolescents living in Montenegro and Kosovo in order to optimize the physical fitness as a consequence of the proactive behavior. Anthropometric characteristics and fitness level measures were assessed by Eurofit testing battery among 600 Kosovar and 600 Montenegrin students, equally distributed by gender. Differences between countries, gender, and age group (13, 14 and 15 years) were assessed with multivariate and univariate analysis of variance. The results showed that Montenegrin students are taller, heavier, and achieve better results in the sit-ups and 20-m endurance shuttle-run tests. Kosovar students achieve better results in the standing broad jump and 10 × 5 m shuttle-run tests. Males achieve significantly better results in all tests, excluding the sit-and-reach test. Statistically significant differences among age groups were found for all variables, regardless gender and country (except for the flamingo and sit-and reach tests). This study is of importance to physical education teachers and curriculum authors to optimize students’ proactive behavior based on the identified anthropometric and physical fitness differences between the two countries, age groups, and genders.