Heart rate variability during motor and cognitive tasks in females with major depressive disorder

Abstract 

Research indicates that major depressive disorder (MDD) is associated with alterations in autonomic control, particularly cardiac control as measured by heart rate variability (HRV). In this preliminary study, we investigated the neural correlates of autonomic control by measuring both HRV and associated brain activity during the performance of mildly stressful tasks. Medically healthy female subjects with MDD (N=10) and healthy controls (N=7) underwent H₂¹⁵O-positron emission tomography (PET) and electrocardiographic ECG recording while performing a handgrip motor task and an n-back task. Indices of HRV were calculated and correlated with regional cerebral blood flow (rCBF). Differences in the rCBF and HRV correlations between depressed and healthy subjects were evident in both the medial and lateral orbital cortices. In addition, these areas appeared to be involved in different facets of autonomic control with regard to sympathetic or parasympathetic dominance of cardiac control. These results are consistent with the known roles of networks within the orbital cortex in both autonomic control and the pathophysiology of MDD.

Abbreviations: MDD, major depressive disorder, HRV, heart rate variability, PFC, prefrontal cortex, OFC, orbitofrontal cortex, MOFC, Medial OFC, LOFC, Lateral OFC, FPC, Frontal Polar Cortex, dmSFG, dorsomedial superior frontal gyrus, HR, Heart rate, lnHF, Natural log of high frequency power of the heart rate spectrum, an indicator of parasympathetic activation, lnLF, Natural log of low frequency power of the heart rate spectrum, partially dependent on sympathetic tone, but strongly dependent on parasympathetic activity as well, LF/HF, Ratio of low to high frequency power, generally used as an index of the balance of sympathetic to parasympathetic tone, RMSSD, Root mean square of successive differences of R–R intervals

Keywords: Autonomic, PET, MRI, Depression, Brain