Objective: The functions of both the central and peripheral autonomic nervous system, indexed by heart rate variability (HRV), are affected by psychology and physiology. This review summarizes the results of studies comparing the evaluation of HRV parameters between individuals with posttraumatic stress disorder (PTSD) and healthy controls. Methods: Eligible studies (n=499) were identified through literature searches of the EMBASE, Medline, PubMed and Web of Science databases. Nineteen studies met our inclusion criteria. A random effects model was used, and standardized mean differences for highfrequency HRV(HF-HRV), low-frequency HRV(LF-HRV) and the root mean square of successive R-R interval differences (RMSSD) were calculated. Results: Significant effects were found for HF-HRV [p<0.0001, Z=4.18; Hedges’g=-1.58, 95% confidence interval (CI) (-2.32, -0.84); k=14] and RMSSD [p<0.00001, Z=4.80; Hedges’g=-1.96, 95% CI (-2.76, -1.16); k=9] relative to healthy controls. Considerable heterogeneity was revealed, but the main effects for HF-HRV and RMSSD were robust in subsequent meta-regression and subgroup analyses. Conclusion Given the relationships among low vagal state, inflammation, and alterations in brain structure and function, including executive function and emotion regulation, reduced HRV may be regarded as an endophenotype in PTSD research.

Objective: To analyze the distribution characteristics of fluoride and trichloromethane in drinking water in rural schools in Guizhou Province and assess their health risks, so as to provide a scientific basis for ensuring the safety of drinking water in rural schools. Methods: During the dry season (March to May) and wet season (July to September) of 2020 to 2022, 788 rural primary and secondary schools in agricultural counties (districts) in Guizhou Province were selected for investigation by using a direct sampling method. A total of 1 566 drinking water samples were collected from these schools, and the mass concentrations of fluoride and trichloromethane in the water samples were detected. The Mann-Whitney U test was used for intergroup comparison, and a health risk assessment model was employed to evaluate the health risks of students oral intake of fluoride and trichloromethane. Results: From 2020 to 2022, the mass concentrations of fluoride and trichloromethane in the drinking water of rural schools in Guizhou Province all met the standards, and the ranges were no detection to 0.99 mg/L and (no detection to 0.06)×10 -3 mg/L, respectively. The mass concentrations of fluoride in dry and wet seasons were 0.05(0.05,0.10), 0.05(0.05,0.10) mg/L, the mass concentrations of trichloromethane were [0.02(0.02,1.00)]×10 -3 , [0.02(0.02,1.00)]×10 -3 mg/L, the mass concentrations of fluoride in factory water and terminal water were 0.05(0.05,0.05), 0.05(0.05,0.10) mg/L, and the differences were not statistically significant ( Z=-0.04, -0.88, - 0.98 , P >0.05). There was a statistically significant difference in the mass concentration of trichloromethane between factory water and peripheral water [0.02(0.02,0.02)×10 -3 , 0.02(0.02,1.05)×10 -3 mg/L]( Z=-2.16, P < 0.05 ). The non-carcinogenic risk assessment values for students oral exposure to fluoride and trichloromethane were in the range of 0.01(0.01,0.03)-0.03(0.03,0.06) and [0.26( 0.26 ,14.54)]×10 -4 -[0.52(0.52,48.62)]×10 -4 , respectively, all of which were at acceptable levels; the carcinogenic risk assessment values for oral exposure to trichloromethane were in the range of [0.08(0.08, 4.51 )]×10 -7 -[0.16(0.16,15.07)]×10 -7 , indicating a low risk. Conclusions The health risks of students expore to fluoride and trichloromethane in drinking water in rural schools of Guizhou Province are low. It is necessary to strengthen the standardized management of disinfection in some rural drinking water projects and the monitoring of fluoride in water sources to reduce the exposure risk to children.

Background The activity in precuneus within default mode network has been reported to be associated with antidepressant response,whereas the relationship between the functional network of precuneus and early response to antidepressant medications remains unclear.Objective To investigate the relationship between precuneus functional connectivity(FC)and early efficacy of antidepressant treatment in patients with major depressive disorder,so as to find a neurobiomarker to predict the early efficacy of antidepressants.Methods A consecutive sample of 47 patients with major depressive disorder who attended the Mental Health Center,West China Hospital of Sichuan University from July 2017 to February 2019 and fulfilled the diagnostic criteria of Diagnostic and Statistical Manual of Mental Disorders,fifth edition(DSM-5)were recruited.Baseline resting-state functional magnetic resonance imaging scan findings and clinical assessments were recorded in participants.All patients treated with antidepressants for two weeks.Improvement was defined as 20%or greater reduction in baseline 16-item Quick Inventory of Depressive Symptoms Self-Report Scale(QIDS-SR16)by treatment exit,and patients were then classified into early improved group(n=27)and non-improved group(n=20).FC values of precuneus and whole brain were calculated using bilateral precuneus as seed region,and baseline precuneus FC values were compared between two groups.Pearson correlation analysis was utilized to explore the correlation between FC values in brain regions with statistically significant differences and QIDS-SR16 total scores and reduction rates.Results FC values between the left precuneus and left precentral gyrus and between the right precuneus and right fusiform gyrus in early improved group were both higher than those in non-improved group(GRF correction,P<0.01).The FC valves between the left precuneus and the left precentral gyrus and between the right precuneus and the right fusiform gyrus were positively correlated with QIDS-SR16 reduction rate(r=0.475,0.297,P<0.05).Conclusion Weakened FC between the left precuneus and left precentral gyrus and between the right precuneus and right fusiform gyrus are related to poor early efficacy to antidepressant treatment,and FC of precuneus may be a potential predictor of early response to antidepressants.