depression is associated with cardiac autonomic dysregulation.Objective: Altered cardiac autonomic function has been proposed in patients with major depression (MD), but the results are mixed. Therefore, analyses with larger sample sizes and better methodology are needed. Methods: To examine whether cardiac autonomic dysfunction is associated with MD, 498 unmedicated patients with MD and 462 healthy volunteers, aged 18-65 years, were recruited for a case-control analysis. We used the Hamilton Depression Rating Scale (HAM-D) and the Beck Depression Inventory (BDI) to assess depression severity. Cardiac autonomic function was evaluated by measuring heart rate variability (HRV) parameters. Frequency-domain indices of HRV were obtained. Results: Patients with MD exhibited reduced cardiac vagal control compared to healthy volunteers, and depression severity was negatively correlated with cardiac vagal control. Stratified analyses by suicide ideation revealed more pronounced cardiac vagal withdrawal among MD patients with suicide ideation. Conclusion: This study shows that MD is associated with cardiac autonomic dysregulation, highlighting the importance of assessing HRV in currently depressed patients, given the higher risk for cardiac complications in these individuals. Taking into account that suicidal depressed patients had more adverse patterns of HRV, one might consider the treatment to restore the autonomic function for the patient population having increased susceptibility to autonomic dysregulation. Significant outcomes• Patients with MD exhibited reduced cardiac vagal control compared to healthy volunteers. • Depression severity was inversely correlated with cardiac vagal control. • The subgroup of MD with suicide ideation revealed more pronounced cardiac vagal withdrawal. Limitations• Causality cannot be inferred from our cross-sectional data.• We fail to use non-linear techniques, which may be more sensitive to depression than linear techniques, to measure HRV. • Interpretation of LF as sympathetic activity should be made with caution in our study.

Many studies have indicated that the norepinephrine transporter (NET) may play an important role in the mechanisms underlying affective disorders. Thus, the genes of the NET (SLC6A2) are good candidates for research on bipolar disorder (BPD). This study examined whether the NET gene is a susceptibility factor for the BPD in Han Chinese. A promoter -182 T/C polymorphism (rs 2242446) and the exonic polymorphism 1287 G/A (rs 5569) of the NET gene were analysed using a polymerase chain reaction (PCR)-based method in 261 BPD patients and 245 unrelated, age- and gender-matched controls. Furthermore, to reduce the clinical heterogeneity, we also carried out analysis in clinical subgroups of bipolar patients defined according to type I and type II BPD, presence or absence of family history of major affective disorders and the age at onset of BPD. No significant difference was found between either bipolar patients or its more homogeneous subgroups and healthy controls in the genotype and allele frequencies for the investigated NET polymorphisms. Our results suggest that the investigated polymorphisms of NET are not major risk factors responsible for predisposition to BPD or its clinical subtypes in Han Chinese. However, replication studies with larger different ethnic samples are needed.

Our study shows that cardiac autonomic dysregulation is not shown in remitted MDD patients as a whole but is limited to the subgroup of remitted MDD patients with a history of suicidal ideation. In view of the higher risk for cardiac complications in these vulnerable individuals, one might consider the treatment to restore their autonomic function.

This study does not support the role of DRD3 Ser9Gly polymorphism in increasing genetic risk for schizophrenia in Han Chinese population. Still, there is a possibility that the DRD3 Ser9Gly variant may reflect genetic variation of severity of positive symptoms in acutely exacerbated schizophrenia. Further studies are warranted to investigate the effect of the DRD3 Ser9Gly polymorphism in relation to longer time course of schizophrenia, including treatment response to antipsychotics.