[Probe variables: a tool for identification of unmeasured confounders in an observational study]

Genetic prediction of the causal relationship between schizophrenia and tumors: a Mendelian randomized study

Background

Patients with schizophrenia are at a higher risk of developing cancer. However, the causal relationship between schizophrenia and different tumor types remains unclear.

Methods

Using a two-sample, two-way Mendelian randomization method, we used publicly available genome-wide association analysis (GWAS) aggregate data to study the causal relationship between schizophrenia and different cancer risk factors. These tumors included lung adenocarcinoma, lung squamous cell carcinoma, small-cell lung cancer, gastric cancer, alcohol-related hepatocellular cancer, tumors involving the lungs, breast, thyroid gland, pancreas, prostate, ovaries and cervix, endometrium, colon and colorectum, and bladder. We used the inverse variance weighting (IVW) method to determine the causal relationship between schizophrenia and different tumor risk factors. In addition, we conducted a sensitivity test to evaluate the effectiveness of the causality.

Results

After adjusting for heterogeneity, evidence of a causal relationship between schizophrenia and lung cancer risk was observed (odds ratio [OR]=1.001, 95% confidence interval [CI], 1.000-1.001; P=0.0155). In the sensitivity analysis, the causal effect of schizophrenia on the risk of lung cancer was consistent in both direction and degree. However, no evidence of causality or reverse causality between schizophrenia and other tumors was found.

Conclusion

This study elucidated a causal relationship between the genetic predictors of schizophrenia and the risk of lung cancer, thereby providing a basis for the prevention, pathogenesis, and treatment of schizophrenia in patients with lung cancer.

[Impact of middle- and long-distance running on mental health in college students in Guangzhou during COVID-19 outbreak]

OBJECTIVE

To investigate the impact of middle- and long-distance running on mental health of students in a college in Guangzhou during the COVID-19 outbreak.

METHODS

We collected data using online questionnaires from the college students selected via snowball sampling. After exclusion of invalid questionnaires and matching the data of running exercise with physical test scores of the participants, 1022 questionnaires were deemed valid for analysis. Of the 1022 students, 869 completed at least a 60-km running distance each semester as required and 153 students did not complete the task. The mental health status of the students was evaluated using PTSD Checklist-Civilian Version (PCL-C), Zung Self-rating Anxiety Scale (SAS) and Self-Rating Depression Scale (SDS). The scale scores were compared between the students who completed the running task and those who did not, and the factors affecting anxiety and depression were analyzed using univariate analysis and binary logistic regression.

RESULTS

The students who completed the running task had significantly higher physical test scores than those who did not complete the task (P < 0.05). The PCL-C, SDS, SAS scale scores or the conditions of PTSD, anxiety, and depression did not differ significantly between two groups (P>0.05). Binary logistic regression analysis indicated that completing the running task or not did not affect the condition of PTSD, anxiety, or depression of the students; a higher physical test score was associated with a decreased risk of PTSD (OR=0.98, 95%CI: 0.97-0.99) and depression (OR=0.99, 95%CI: 0.97-1.00) but an increased risk of anxiety (OR=1.02, 95%CI: 1.01-1.04) during COVID-19 outbreak.

CONCLUSION

Regular middleand long-distance running exercise may enhance the physical health to indirectly promote the mental health of the college students during COVID-19 outbreak.