Causal associations between digital device use and suicide risk: A bidirectional Mendelian randomization study

BACKGROUND

The popularity of digital devices seems to provide a new observational variable for early identification and prevention of suicide with the development of the information technology era. Nevertheless, whether it is the use of digital devices that alters suicide risk or suicide risk manifests itself through change digital device use needs to be further explored.

METHODS

Bidirectional Mendelian randomization (MR) analysis was used to explore potential causal relationships in the perspective of genetic prediction. We collected publicly available digital device use and suicide risk summary statistics genome-wide association data from UK Biobank, Neale Lab and FinnGen genetic databases. We used inverse variance weighting methods to assess MR estimates. For robustness of the results, we performed further tests of heterogeneity and pleiotropy.

RESULTS

In the Phase 1 results, we did not observe any effect of the length of digital device use on the suicide risk, while the results of Phase 2 suggested a significant positive association between suicide risk and the length of mobile phone use (IVW OR, 1.04; 95%CI, 1.01-1.06; P = 0.002), but this significance disappeared after adjusting for confounders of mental and affective disorders.

CONCLUSIONS

In this bidirectional MR analysis, we observed that People at high risk of suicide may be more addicted to digital device use, but more detailed GWAS data and research methods to validate this finding are required.

Dose-response association of total sedentary behaviour and television watching with risk of depression in adults: A systematic review and meta-analysis

BACKGROUND

Although sedentary behaviour has been increasingly linked to depression, evidence remains conflicted and meta-analysis of the dose-response associations in adults is lacking. We aimed to explore the quantitative dose-response association of total sedentary behaviour and television watching with depression among adults.

METHODS

We systematically searched PubMed, Embase and Web of Science for articles to identify observational studies that assessed the association of total sedentary behaviour and television watching with depression in adults. Summary risk ratios (RRs) and 95 % confidence intervals (CIs) were estimated for the dose-response association by using a fixed or random-effects model. Restricted cubic splines were used to evaluate the possible linear or non-linear relations.

RESULTS

We included 16 studies with 221,599 participants in this meta-analysis, 10 for total sedentary behaviour and 6 for television watching. The summary RR of depression for the highest versus lowest total sedentary behaviour and television watching were 1.42 (95 % CI: 1.22-1.67) and 1.26 (95 % CI: 1.14-1.40), respectively. We found a non-linear association between total sedentary behaviour and depression. For participants with total sedentary time 8 h/day and 9 h/day, the risk of depression was increased by 20 % (RR 1.20, 95 % CI 1.09-1.29) and 29 % (RR 1.29, 95 % CI 1.20-1.40), respectively. A linear dose-response association was observed between television watching and depression. For each 1 h/day increase in television watching, risk of depression was increased by 5 % (RR: 1.05, 95 % CI: 1.02-1.09).

CONCLUSIONS

Depression may be associated with increased time spent in total sedentary behaviour and television watching.

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.

Unrestricted prevalence of sedentary behaviors from early childhood

Background

Light and sedentary behaviors impose heavy challenges on societies. The objectives of this study are to identify child sedentary behaviors, and to examine the relationship between parent knowledge and behavioral style on children’s sedentary time in Iran.

Methods

This cross-sectional study was done among children and their parents selected randomly using multi-stage method, from 12 urban districts in Tabriz, Iran;2017. Data were collected through designing a multi-sectional questionnaire adopted from the Bjelland and previous studies to assess the time spent on sedentary behaviors among children/adolescents along with parent knowledge and behavioral style.

Results

From 480 children/adolescents and their parents 54.6% came from middle class families, and 55.62% were boys aged 2 to18. The percentage of time spent more than 120 min per day (min/d) on weekdays was for watching television (TV): (girls 24.4%, boys 21.0%), for playing computer and video games: (girls 38.7%, boys 54.7%), for electronic media communication (EMC): (girls 52.8%, boys 60.2%). The associated factors for watching TV: child age [12 years and above OR = 1.37; 95% CI = 0.53–3.54], parent knowledge [OR = 0.59, 95% CI = 0.35–0.99], and communicative styles [OR = 1.43, 95%CI = 1.11–1.86], and for playing computer and EMC: child age [5 years old and above OR = 4.83,95% CI =1.52–15.38, 12 years old and above OR = 13.76, 95% CI= 4.22–24.91], family socio-economic status [middle class OR = 2.52, 95% CI = 1.54–4.11, high class OR = 5.53, 95%CI = 1.80–15.89].

Conclusion

There is an urgent need to combat the unrestricted prevalence of sedentary behaviors among Iranian children/ adolescents who use computers and other electronic devices more than the recommended time every day from early childhood.

Parents should be provided with appropriate information about adverse effects of using electronic devices longer than recommended time by children. It is also essential to teach them beneficial communicative styles to monitor their children’s sedentary behaviors.

Association between education and television viewing among older working and retired people: a comparative study of Finland and Japan

Background

Educational attainment is associated with physical activity among older people. However, little is known about its association with sedentary lifestyle in European as well as Asian nations. This study aims to examine the associations between educational attainment and daily television viewing as an indicator of a sedentary lifestyle among older working and retired people in Finland and Japan.

Methods

We used cross-sectional harmonized data from two cohorts, the Finnish Public Sector study (n = 10,744) and the Japan Gerontological Evaluation Study (n = 2493), evaluating individuals aged 65–75 years old. We defined high-duration television viewing as ≥4 h per day. Poisson regression was used to examine the association between educational attainment and high-duration television viewing, stratified by the current working status. Models were adjusted for age, sex, household size, smoking, alcohol, body mass index, chronic diseases, mental disorders, and physical activity.

Results

Of the participants, 27% in Finland and 30% in Japan reported high-duration television viewing. Compared with a low education (≤9 years), Finnish and Japanese retirees with a high education (≥13 years) had less high-duration television viewing [prevalence ratio, PR 0.68 (95% confidence interval 0.63–0.73) and 0.66 (0.55–0.79), respectively]. The corresponding PRs for Finnish and Japanese retirees with intermediate education were also lowered [0.89 (0.83–0.95) and 0.79 (0.68–0.91), respectively]. Among older people still at work, educational attainment was associated with high-duration television viewing among the Japanese but not among the Finnish.

Conclusion

A similar association between educational attainment and high-duration television viewing in Finland and Japan particularly after retirement suggests a robust and consistent impact of educational attainment on a sedentary lifestyle after retirements.

Electronic supplementary material

The online version of this article (10.1186/s12889-018-5860-4) contains supplementary material, which is available to authorized users.

Influence of socio-economic status and television watching on childhood obesity in Kolkata

Obesity is fast becoming an epidemic among the urban children and it has its adverse effect on the status of health even during adulthood. In this paper an attempt is made to assess the percentage of obesity among 6-10 year children and assess the effect of different socio-economic variables and TV watching on childhood obesity. We restricted our study to primary school-going children who attended classes I-IV. The sample consisted of 5216 children from 20 different Bengali medium and English medium schools in Kolkata. Categorical logistic regression of obesity on the socio-economic factors namely type of medium school, religion, parent's education, duration of television watching etc., has been carried out. The categorical logistic regression shows the significant effect of some of the socio-economic or demographic variables including the duration of television watching on obesity. We have seen a positive association between obesity and TV watching and also between obesity and consumption of fast food. This calls for making the parents aware and taking action as early as possible.

Children's Hyperactivity, Television Viewing, and The Potential for Child Effects

Using data from the Early Childhood Longitudinal Study-Birth Cohort (ECLS-B; n = 6,250), this study examined whether children who display difficult behaviors early in life watch more television from year-to-year. Results revealed that 4-year-old children's hyperactive, but not aggressive, behavior was associated with an increase in television watching over the ensuing year. These potential child effects, however, were embedded in both proximate and distal ecologies. That is, the association between children's hyperactivity and increases in their television exposure over time was strongest among those in the low-end of the socioeconomic distribution and those whose parents displayed less optimal mental health. It was also stronger among girls. These results underscore the importance of considering child effects in future research and how intra-familial dynamics vary across different types of family contexts.

Television watching and colorectal cancer survival in men

PURPOSE

To assess the association between pre- and postdiagnostic time spent sitting watching TV as well as other sedentary behaviors (other sitting at home and at work/driving) and mortality from colorectal cancer or other causes, and overall mortality.

METHODS

We followed stage I-III colorectal cancer patients from the Health Professionals Follow-up Study (1986-2010). Cox models were used to calculate hazard ratios (HRs) and 95 % confidence intervals (CIs).

RESULTS

A total of 926 and 714 patients were included in the analysis of pre- and postdiagnostic TV watching, respectively, and 471 and 325 died during follow-up. Prolonged prediagnostic TV viewing was associated with increased risk of colorectal cancer-specific mortality independent of leisure-time physical activity. The HRs (95 % CIs) for 0-6, 7-13, 14-20, and ≥21 h/week were 1.00 (referent), 0.84 (0.56-1.25), 1.15 (0.75-1.78), and 2.13 (1.31-3.45) (p trend = 0.01). The association was observed primarily among overweight and obese individuals. Prediagnostic TV watching was also associated with overall mortality within 5 years of diagnosis, largely due to the association with colorectal cancer mortality. Other prediagnostic sitting at home or at work/driving was not associated with mortality. Postdiagnostic TV viewing was associated with a nonsignificantly increased risk of colorectal cancer-specific mortality (HR for ≥21 vs 0-6 h/week = 1.45; 95 % CI 0.73-2.87) adjusting for TV viewing before diagnosis.

CONCLUSION

Prolonged prediagnostic TV watching is associated with higher colorectal cancer-specific mortality independent of leisure-time physical activity among colorectal cancer patients.