Exploring the Relationship Between Schizophrenia and Cardiovascular Disease: A Genetic Correlation and Multivariable Mendelian Randomization Study

Individuals with schizophrenia have a reduced life-expectancy compared to the general population, largely due to an increased risk of cardiovascular disease (CVD). Clinical and epidemiological studies have been unable to unravel the nature of this relationship. We obtained summary-data of genome-wide-association studies of schizophrenia (N = 130 644), heart failure (N = 977 323), coronary artery disease (N = 332 477), systolic and diastolic blood pressure (N = 757 601), heart rate variability (N = 46 952), QT interval (N = 103 331), early repolarization and dilated cardiomyopathy ECG patterns (N = 63 700). We computed genetic correlations and conducted bi-directional Mendelian randomization (MR) to assess causality. With multivariable MR, we investigated whether causal effects were mediated by smoking, body mass index, physical activity, lipid levels, or type 2 diabetes. Genetic correlations between schizophrenia and CVD were close to zero (−0.02–0.04). There was evidence that liability to schizophrenia causally increases heart failure risk. This effect remained consistent with multivariable MR. There was also evidence that liability to schizophrenia increases early repolarization pattern, largely mediated by BMI and lipids. Finally, there was evidence that liability to schizophrenia increases heart rate variability, a direction of effect contrasting clinical studies. There was weak evidence that higher systolic blood pressure increases schizophrenia risk. Our finding that liability to schizophrenia increases heart failure is consistent with the notion that schizophrenia involves a systemic dysregulation of the body with detrimental effects on the heart. To decrease cardiovascular mortality among individuals with schizophrenia, priority should lie with optimal treatment in early stages of psychosis.     

The Relationship Between Theory of Mind and Executive Function in a Sample of Children from Mainland China

To explore the relationship between theory of mind (ToM) and executive function (EF) in a sample of individuals from mainland China, 20 children with autism spectrum disorders (ASD), 26 children with Attention Deficit Hyperactivity Disorder (ADHD), and 30 normal control subjects were compared on two batteries of ToM tasks and EF tasks. Children with ASD had a significant theory of mind impairment relative to the other controls, while non-verbal IQ removed group differences in executive function. ToM was significantly correlated with inhibitory control. Performance on inhibitory control tasks, however, did not affect performance on ToM tasks.     

Heart rate variability during sleep and the early development of posttraumatic stress disorder

Background

Noradrenergic function has been linked to posttraumatic stress disorder (PTSD) and might have a role in mediating sleep disturbances of the disorder. Our objective was to relate a peripheral manifestation of noradrenergic function, sympathetic nervous system activity as indexed by heart rate variability during sleep, to the development of PTSD in subjects with recent traumatic injuries.

Methods

Subjects who had recall of life-threatening experiences were recruited from one of two regional trauma centers. Select subjects received a polysomnographic recording within 1 month of the trauma. Digitized electrocardiogram recordings were extracted from early and late rapid-eye-movement (REM) and preceding non-REM sleep periods. Autoregression was applied to R-R interval time series to calculate the ratios of low-frequency to high-frequency spectral densities (LF/HF ratios), which index sympathetic activation. Posttraumatic stress disorder status was determined at 2 months.

Results

There was a significant state × group interaction: LF/HF ratios were higher during the REM sleep of the nine subjects who were positive for PTSD symptoms, compared with the 10 subjects who were PTSD negative.

Conclusions

Our findings are consistent with the possibility that increased noradrenergic activity during REM sleep contributes to the development of PTSD.     

失眠症患者睡眠质量与心理健康状况及心率变异性的关系

目的:探讨失眠症患者睡眠质量与心理健康状况及心率变异性(HRV)的关系。方法:对165例失眠症患者进行匹兹堡睡眠质量指数问卷(PSQI)评估,并据此分为高分组85例与低分组80例;采用生理相干与自主平衡训练系统(SPCS)采集HRV,应用症状自评量表(SCL-90)评估患者心理健康状况。结果:高分组SCL-90中焦虑因子及睡眠与饮食因子得分显著高于低分组(P均0.05);两组患者HRV中总功率(TP)、低频功率(LF)、高频功率(HF)、LF/HF比值差异有统计学意义(P均0.05);PSQI总分与HRV中TP、LF、HF呈正相关(r=0.196,0.185,0.223;P0.05或P0.01),与LF/HF呈负相关(r=-0.304,P0.01)。结论:严重失眠的患者易产生焦虑情绪;失眠严重程度与自主神经系统功能失调程度相关。