Dynamical Cardiovascular Synchrony in Patient-caregiver Dyads Affected by Cancer: An Application of the Coupled Linear Oscillator Model.

[OBJECTIVE] To examine moment-to-moment cardiovascular coordination between patients with cancer and their family caregivers during acute interpersonal stress, using a dynamical systems modeling approach.

[METHODS] Second-by-second interbeat interval (IBI) data from 134 adult patients with colorectal cancer and their family caregivers were continuously recorded across six phases of an experimental stress task: baseline, stress scenario, preparation, caregiver speech, patient speech, and recovery. The coupled linear oscillator (CLO) model was used to estimate each partner's oscillatory frequency and amplitude (damping vs. amplification), as well as cross-partner coupling.

[RESULTS] Across all task phases, both patients and caregivers showed rhythmic cardiovascular oscillations and cross-partner coupling, indicating synchronized cardiovascular activity. Co-regulation (damping with coupling) and co-agitation (amplification with coupling) were not statistically supported overall. Descriptive trajectory plots suggested phase-dependent patterns: minimal oscillation during baseline, increased amplitude during the stress-evoking scenario, and increased damping and coupling during the speech phases. Additionally, coupling effects were stronger for the speaking partner.

[CONCLUSIONS] This study applied a dynamical systems approach to model moment-to-moment cardiovascular coordination in patient-caregiver dyads during acute stress. Findings revealed unique cardiovascular synchrony patterns in patient-caregiver dyads that varied by stress type (i.e., the specific stress phase) and the roles within the relationship (speaker vs. listener). Future research should examine psychosocial predictors and long-term health outcomes associated with specific cardiovascular co-regulation and co-agitation patterns, and apply this statistical approach to other markers of moment-to-moment interpersonal processes, such as emotional linkage and behavioral synchrony (e.g., rest-activity patterns).