Older adults' contribution to informal caregiving : profiles, adverse health consequences, and support interventions

Background: Population aging has led to a growing reliance on informal caregiving, with an increasing number of older adults providing care to relatives, partners, or friends. While informal caregiving can be a meaningful experience, it is also associated with adverse subjective and objective health outcomes. Evidence on the health impact of caregiving in later life remains inconsistent, partly due to heterogeneity among caregivers and methodological limitations of prior research. The overall aim of this thesis was to examine the heterogeneity of informal caregiving in old age and its associations with subjective burden and objective health outcomes, today and over time, and review evidence on health-enhancing support interventions, using various data sources and methods. Study I: Study I used data from the Swedish National study on Aging and Care in Kungsholmen (SNAC-K), a population-based cohort of 3,363 adults aged ≥60 years. At baseline, 629 participants (19.2%) were identified as informal caregivers. Cross-sectional and longitudinal analyses were conducted to examine associations between caregiving characteristics and subjective and objective health outcomes. Caring for a spouse, living in the same household as the care receiver, providing more hours of care, and having a dual role as both caregiver and care receiver were associated with higher perceived burden and limitations to life. Over 12 years of follow-up, having a dual role (B -0.12, 95% CI -0.23 to -0.02) and providing spousal care (ß -0.08, 95% CI -0.14 to -0.02) were associated with a faster decline in objective health status. Women and caregivers with poorer social networks experienced steeper health declines. Study II: Study II used data from a national, representative survey of older adults in Sweden conducted between May and September 2023. A total of 25,776 individuals aged 265 years were sampled, with 15,129 respondents (58.7%). Among respondents, 2,157 individuals (14.3%) were informal caregivers. Most caregivers provided low-intensity care (1-10 hours per week; 68.6%), while 16.8% provided at least 30 hours care per week. Women (63.1%) and caregivers aged >75 years (64.1%) were overrepresented among those providing high-intensity care. Higher caregiving intensity was associated with more negative experiences, worse self- rated health, and greater unmet support needs. Study III: Study III was a nationwide register-based matched cohort study of community-dwelling adults aged 270 years in Sweden. The exposed group included 6,068 individuals whose spouse experienced a first stroke in 2014 or 2015, matched to 91,204 unexposed controls. During up to six years of follow-up, spouses of stroke survivors had a modestly increased risk of all-cause mortality compared to controls (adjusted hazard ratio 1.13, 95% CI 1.06-1.20). No significant differences were observed for cardiovascular events, infections, hospitalizations, or psychotropic drug use. Study IV: Study IV was an umbrella review of systematic reviews and meta- analyses evaluating interventions designed to mitigate the negative health outcomes of informal caregiving to older adults. A total of 47 reviews were included, covering 619 unique primary studies. Quantitative evidence on intervention effectiveness for physical and mental health outcomes was highly discordant, while qualitative evidence consistently reported practical, emotional, and relational benefits. Multicomponent and person-centered interventions appeared more effective and acceptable than single-component approaches. Overall, the review identified substantial heterogeneity in caregivers, care contexts, and outcomes, as well as limitations related to evidence quality and overlap between reviews. Conclusions: Across multiple data sources and study designs, this thesis shows that informal caregiving in later life is a heterogeneous experience, with health and well-being consequences depending strongly on caregiving intensity, role configuration, and social context. High-intensity caregiving, spousal caregiving, and dual caregiver-care receiver roles are consistently associated with greater subjective burden, poorer self-rated health, and steeper declines in health, although population-level register data suggest that average morbidity effects may be modest or difficult to detect. These findings highlight the need for greater recognition of informal caregiving as a potential source of sustained burden, and for support strategies that help caregivers maintain a sense of meaning and engagement without compromising their health. Evidence on the effectiveness of caregiver support interventions remains inconclusive, while supporting the need for targeted, person-centered approaches rather than uniform solutions. List of scientific papers This doctoral thesis includes three original papers and one systematic umbrella review, referred to as Studies I, II, III and IV throughout the text. I. Kirvalidze M*, Beridze G*, Wimo A, Morin L, Calderón-Larrañaga A. Variability in perceived burden and health trajectories among older caregivers: a population-based study in Sweden. J Epidemiol Community Health. 2023 Feb;77(2):125-132. https://doi.org/10.1136/jech-2022-219095 *Shared first authorship II. Kirvalidze M, Hanson E, Magnusson L, Dahlberg L, Wimo A, Morin L, Calderón-Larrañaga A. The intensity of informal caregiving and its implications for older caregivers: a national survey in Sweden. Scand J Public Health. 2025 May 1:14034948251335113. https://doi.org/10.1177/14034948251335113 III. Kirvalidze M, Wastesson J, Beridze G, Dahlberg L, Hanson E, Johnell K, Calderón-Larrañaga A, Morin L. Spousal health following partner stroke: a register-based matched cohort study. [Submitted] IV. Kirvalidze M, Abbadi A, Dahlberg L, Sacco LB, Morin L, Calderón-Larrañaga A. Effectiveness of interventions designed to mitigate the negative health outcomes of informal caregiving to older adults: an umbrella review of systematic reviews and meta-analyses. BMJ Open. 2023 Apr 21;13(4):e068646. https://doi.org/10.1136/bmjopen-2022-068646 Study I. C Kirvalidze et al., 2023. Published by BMJ Publishing Group (CC BY 4.0) Study II. @ Kirvalidze et al., 2025. Published by SAGE publishing (CC BY 4.0) Study IV. C Kirvalidze et al., 2023. Published by BMJ Publishing Group (CC BY 4.0)