Changes of cardiac autonomic nervous function and nonlinear EEG analysis in patients with depression

Abstract

Objective To study the changes of cardiac autonomic nervous function and EEG non-linear dynamics character in depressive patients, and to explore the functional activity state of brain. Methods 24-hour ambulatory ECG was recorded in 47 depressive patients and 47 normal control people by multi-channel ECG machine. The index of heart rate variability, the incidence of arrhythmias and the relationship between HRV and the severity of depression were analyzed. Results Compared with the control group, the standard deviation of NN intervals(SDNN)((91.31±15.11)ms), the standard deviation of normal number of intervals(SDANN)((82.14±16.26)ms), the root mean square of successive differences (RMSSD)((37.13±8.02)ms), the percentage of pairs of adjacent RR intervals differing by >50 ms (PNN50)(11.05±7.02) and High-frequency(HF)((17.07±4.34)ms) in depression group were lower, however low-frequency(LF)((18.27±6.32)ms) and LF/HF((1.07±0.33)ms) were higher(P<0.05). There were positive linear correlation between depression severity and LF/HF(P <0.05, r=0.332) and negative linear correlation between depression severity and SDNN(P<0.05, r=-0.296). Compared with control group, the incidence rate of arrhythmia of depressive group was increased, especially in supraventricular arrhythmias. In quiet state with eyes closed: compared with the control group, the level of correlation dimension (D2) in left occiput, left middle and behind temple region were increased in group A, but the difference was not statistically significant.In group B, except prefrontal area, the D2 of the left hemisphere were increased especially in the left central area(3.91±0.37), left parietal lobe(3.85±0.43), left occipital(4.10±0.54)and left temporal(4.20±0.61) compared with control group (P<0.01). The brain electrical activity in other areas were not found change. Conclusion The cardiac autonomic nervous function of depressive patient is positively correlated with the the severity of depression.Depressive patients are likelyto conduct supraventricular arraythmia. Left hemisphere cerebral cortex is active in depressive patients by analysing the EEG non-linear dynamics character. Key words: Depression; Autonomic nervous; Heart rate variability; Brain electrical activity mapping; Correlation dimension