Heart rate variability during inpatient treatment of depression

Major depressive disorder (MDD) is linked to reduced heart rate variability, an index of cardiovascular autonomic modulation (CAM). However, treatment effects on CAM are poorly known. Our objective was to assess if initiation of inpatient treatment has a beneficial effect on CAM in MDD patients.

In 30 MDD inpatients, we recorded RR-intervals (RRI), continuous blood pressure (BPsys, BPdia), skin conductance levels (SCL), respiration frequency (RESP) and current medication within 24 h (T1) and 3 weeks after hospital admission (T2) during resting state and metronomic breathing. The same parameters were recorded once at baseline in 30 controls without mental disorders. We computed indices of sympathetic modulation, parasympathetic modulation and parameters reflecting total CAM. Physiological parameters were compared using MANCOVAS. Symptoms of depression were assessed using Hamilton rating scale for depression (HAM-D) and Beck Depression Inventory (BDI), we used rmANOVAs to compare t1 and t2 questionnaire data.

BDI and HAM-D scores were lower at T2 than T1 (both p < 0.01). RRI was lower in T1 patients than in controls (p = 0.021), while BPdia (p = 0.038) and RESP (p = 0.014) were higher in T1 patients than controls. MDD patients showed lower parameters of parasympathetic modulation and total CAM than controls during resting state (parasympathetic p = 0.003; total CAM p = 0.017) and metronomic breathing (parasympathetic p = 0.040; total CAM p = 0.007). Analysis unveiled lower parameters of parasympathetic modulation in T1 patients compared to T2 patients during baseline (p = 0.046). No differences between T1 and T2 patients during metronomic breathing were found.

MDD patients showed lower CAM than controls. Contrary to our assumption, we found a decline of parasympathetic modulation in MDD patients over the observation span despite symptomatic improvement. The decline is presumably due to the initiation of psychopharmacotherapy and changes in premedication.