Informal caregiving trajectories and inflammatory biomarkers: findings from the English Longitudinal Study of Ageing

To date, the evidence on the adverse effects of informal caregiving on stress-related inflammation remains weak, with most studies focusing solely on the transition to caregiving. This study investigates the relationship between trajectories of informal caregiving in later life and inflammatory biomarkers (C-reactive protein [CRP], fibrinogen, and white blood cell count [WBC]) in England.

Data came from the nationally representative English Longitudinal Study of Ageing (ELSA) waves 6 (2012-2013) to 9 (2018-2019). Our sample comprised ELSA core members with valid blood samples in waves 6 and 9 (n = 1,162). Group-based trajectory modelling was used to determine the number and shape of trajectories of informal caregiving hours from waves 6 to 9. Logistic regression models were then used to investigate the associations between informal caregiving trajectories and inflammatory biomarkers in wave 9, adjusting for sociodemographics, wave-6 inflammation, and wave-9 non-inflammatory biomarkers.

We identified 4 informal caregiving trajectories: "stable no care" (72.6%), "light to intensive care" (4.8%), "stable light care" (18.0%), and "intensive to moderate care" (4.6%). Compared with the "stable no care" trajectory, the "intensive to moderate care" trajectory was associated with a higher likelihood of abnormal fibrinogen levels (odds ratio [OR] = 2.97, 95% confidence interval [CI]: 1.31 to 6.69) in the fully adjusted model. No associations were found between informal caregiving trajectories and CRP or WBC.

Overall, informal caregiving had only weak adverse effects on older caregivers' inflammatory biomarkers. However, our findings underscore the importance of supporting persistent intensive caregivers.