Association between depression severity and cardiac autonomic modulation

Changes in autonomic modulation are found in depressive patients. QT dispersion is a convenient measure of cardiac autonomic modulation (CAM). As both QT dispersion and depression are related to changes in CAM, this study aimed to examine if there was an association between depression severity and QT dispersion.

The selected sample (n=60) derived from 236 women who were recruited via a campaign for breast cancer prevention. The women selected to participate were all non-smokers and were not taking any drug that could interfere with the results. After applying inclusion and exclusion criteria, 60 women were selected. QT dispersion (QTd) and rate-corrected QTd (QTcD) were calculated in 37 physically and mentally healthy women and 23 nontreated depressive women. Univariate ANOVA(s) were used to test group differences. The 17-item Hamilton Depression Rating Scale (HDRS17) was scored to measure depression severity. The relationship between depression severity and cardiac autonomic modulation was analyzed by the best curve that fit the raw data of the HDRS17 scores and the QT dispersion variables.

The QTd and QTcD were significantly smaller in non-depressed in relation to the depressed women. The best curve that fit the raw data of depression severity (HDRS17) and the two measurements of cardiac autonomic modulation (QTd and QTcD) was a cubic equation for both QTd and QTcD. An increase in QTd and QTcD were observed until the HDRS17 score reached 20 points.

There is a significant positive relationship between depression severity and cardiac autonomic modulation in mild and moderate depression.