Effect of behavioral activation on time and frequency domain heart rate variability in older adults with subthreshold depression: a cluster randomized controlled trial in Thailand

Abstract

Background Increased prevalence of depression highlights the need for effective interventions. Behavioral activation (BA), which can easily be adapted for non-clinical populations, has been the recommended treatment for depression. It is based on a model of psychopathology explaining that losses or chronically low levels of positive reinforcement yield behavioral and emotional changes in depression and that encouraging individuals to increase their engagement in reinforcing activities can improve their mood and enhance their valuable life experiences. Heart rate variability (HRV) provides indices of autonomic function related to depression, but only a few studies have investigated the effect of BA on HRV, particularly among older adults with subthreshold depression. Accordingly, we aimed to investigate the effect of BA on HRV in older adults with subthreshold depression. Methods We conducted a 9-month cluster randomized controlled trial in two Health Promoting Hospitals (HPHs). Eighty-two participants were randomized into either intervention (BA with usual care) or control (usual care only) groups, with 41 participants per group. Daily step count was collected weekly during the 12-week BA intervention period, while HRV parameters, including the Standard Deviation of the Normal-to-Normal interval (SDNN), High Frequency (lnHF), Low Frequency (LF), and Low Frequency/High Frequency ratio (LF/HF), were examined at 0, 3, 6 and 9 months. Generalized Estimating Equations (GEEs) were used in the data analysis. Results Over nine months, the intervention and control groups differed significantly in the unadjusted mean change of HRV, SDNN [7.59 ms (95% CI: 1.67, 13.50)], lnHF [0.44 ms2 (95% CI: 0.04, 0.85)], and LF [0.53 ms2 (95% CI: 0.09, 0.98)], whereas the groups did not differ significantly in LF/HF ratio [0.01 ms2 (95% CI: -0.04, 0.06)]. Conclusion Our results suggest that BA may have a therapeutic effect on depression symptoms of older adults with subthreshold depression via improved HRV. Trial registration TCTR20211019003, thaiclinicaltrials.org, retrospectively registered on 19 October 2021.

Only one cluster per condition is an invalid design for a cluster randomized trial and should be re-labeled a quasi-experimental study. Response to: “Effect of behavioral activation on time and frequency domain heart rate variability in older adults with subthreshold depression: a cluster randomized controlled trial in Thailand”

“…Ayudhaya et al [ 1 ] conducted a study to examine the effect of Behavioral Activation (BA) on daily step count (as a physical activity indicator) and heart rate variability (as a depression-related autonomic function indicator) among community-dwelling older adults with mild to moderate depression. The article is labeled as a cluster randomized controlled trial (cRCT).…”

“…Thus, the degrees of freedom for testing the intervention effect depends both on the number of individual participants and on the number of clusters per condition [ 3 ]. A purported cRCT with two conditions and only one cluster assigned to each condition, such as Ayudhaya et al’s study [ 1 ], would have zero degrees of freedom (n1 + n2–2) for inferential testing. That is, the variation due to cluster membership cannot be estimated apart from the variation due to treatment assignment, and a valid analysis of the intervention effect could not exist [ 4 ].…”

“…Because in Ayudhaya et al’s study [ 1 ] the intervention effect is completely confounded with the cluster effect, it should be labeled a quasi-experimental study, not a cRCT. Accordingly, the numerical results should be interpreted as associations between BA and the outcomes but not evidence for causal relationships [ 5 ].…”