With accelerating population aging, the phenomenon of “old-to-old caregiving”—where individuals aged 60 years or older care for another elderly patient—has become increasingly prevalent among families of older cancer patients. While caregiving burden and inadequate care capacity among these caregivers represent growing challenges, the underlying mechanistic pathways linking these factors remain insufficiently understood. This study aimed to elucidate the mediating roles of psychological capital and social networks in the relationship between caregiving burden and care capacity among older adult caregivers, providing an evidence base for developing integrated psychosocial interventions to improve home-based care quality.

A cross-sectional design was employed, utilizing convenience sampling to recruit participants from the Radiation Oncology Department of The First Affiliated Hospital of Anhui Medical University between July 2025 and January 2026. A total of 344 valid caregiver-patient dyads were ultimately enrolled. Data were collected using a general information questionnaire (capturing sociodemographic and clinical characteristics), including the Aged Care Aptitude Assessment Scale, Caregiver Burden Scale for Cancer Patients, Positive Psychological Capital Questionnaire and Lubben Social Network Scale-6. Pearson correlation analysis was performed to examine interrelationships among care capacity, caregiving burden, psychological capital, and social networks. Chain mediation analysis was subsequently conducted, adjusting for relevant covariates.

The mean caregiving capacity score among the 344 caregivers was 95.50±12.18, indicating a below-medium level. The mean caregiving burden score was 54.86±6.56 (mild-to-moderate burden), Positive psychological capital was 106.47±14.79 (medium level), and social network score was 12.85±4.15, approaching the threshold for social isolation risk. After adjusting for covariates, multiple regression analysis revealed that caregiving burden significantly and negatively predicted both psychological capital (β=-0.215, P<0.001) and social networks (β=-0.228, P<0.001), while psychological capital positively predicted social networks (β =0.450, P<0.001). Caregiving burden also exerted a significant negative direct effect on caregiving capacity (β =-0.092, P=0.016), whereas psychological capital (β =0.574, P<0.001) and social networks (β =0.167, P<0.001) significantly and positively predicted caregiving capacity. The chain mediation model demonstrated significant indirect effects. The total effect of burden on capacity was -0.270 (95%CI: -0.369 to -0.171), with a direct effect of -0.092 (95%CI: -0.167 to -0.017). The total indirect effect was -0.178 (95%CI: -0.255 to -0.102), accounting for 65.9% of the total effect. Specifically, the mediating effect via psychological capital alone was -0.124 (95%CI: -0.191 to -0.060; 45.9% of total effect), via social networks alone was -0.038 (95%CI: -0.070 to -0.014; 14.1% of total effect), and the chain mediation effect through both psychological capital and social networks sequentially was -0.016 (95%CI: -0.030 to -0.005; 5.9% of total effect).

Psychological capital and social networks serve as significant sequential mediators in the relationship between caregiving burden and care capacity among older adult caregivers of cancer patients. These findings underscore the necessity for clinical healthcare providers to implement integrated psychosocial support strategies targeting both psychological resilience and social connectivity to mitigate the adverse impact of caregiving burden and enhance the quality of home-based care for this vulnerable population.