Changes in salivary oxytocin and subjective well-being in older women participating in direct or remote intergenerational exchange with children: a prospective observational study

Abstract Background This study examined changes in salivary oxytocin concentrations and subjective well-being accompanying direct and remote intergenerational exchange with children in older women. Given the increasing use of remote communication, we also examined whether similar physiological and psychological changes were observed in the remote condition. Methods We conducted a prospective observational cohort study among community-dwelling older women in Japan. Participants took part in either a direct face-to-face exchange or a remote exchange via video call. Saliva was collected at 10:00 (T1) and 11:00 (T2) on the reference day and at 11:00 on the exchange day (T4). The primary outcome was salivary oxytocin concentration, with the primary contrast defined as T4 relative to the same-clock-time T2 measurement on the reference day. Subjective well-being was assessed using the Personal Wellbeing Index (PWI) and a numerical rating scale (NRS) from T1 to T6 and analyzed using linear mixed-effects models. Sensitivity analyses were also performed. Results Forty-six women enrolled; 40 were included in the final analysis (Direct, n = 18; Remote, n = 22). The geometric mean ratio (GMR) of salivary oxytocin at T4 relative to T2 was 1.220 (95% CI 0.987–1.507) in the Direct group and 1.046 (95% CI 0.851–1.284) in the Remote group. The ratio of GMRs for Direct versus Remote was 1.166 (95% CI 0.877–1.551), with no evidence of a between-group difference. PWI and NRS showed positive changes from immediately before to immediately after the exchange, but changes in the same direction were also observed on the reference day. Neither outcome showed a significant group-by-time interaction. Conclusions In the Direct group, salivary oxytocin at T4 was estimated to be higher than at the same-clock-time T2 measurement on the reference day, but the primary analysis was not statistically significant and there was no evidence of a between-group difference. Positive changes in subjective well-being around the exchange were also observed on the reference day and therefore could not be interpreted as exchange specific. These findings underscore the importance of accounting for same-clock-time reference-day measurements and non-specific study-context effects when evaluating short-term physiological and psychological changes accompanying intergenerational exchange.