The risk of cognitive decline after losing a spouse remained mixed. This study aims to investigate the association between spousal loss and risk of cognitive decline, assess whether this association varies by sex and age, and identify modifiable factors.

We conducted a prospective cohort study using harmonized data from six population-based ageing surveys: the US Health and Retirement Study and its sister surveys in England, Mexico, China, India and South Africa, incorporating their respective Harmonized Cognitive Assessment Protocol (HCAP) sub-studies. Spousal loss (yes vs no) was the exposure. Cognitive outcomes (i.e., orientation, memory, executive function and language) were assessed using HCAP neuropsychological batteries. We conducted parallel analyses in six cohorts. Associations between spousal loss and cognitive outcomes were estimated using generalized linear models, and summarised estimates were derived via random-effects meta-analyses. Sex stratification and restricted cubic splines were used to examine how these associations vary by sex and age, respectively.

The analytical cohort consisted of 18,551 individuals aged 61.39 (6.40) to 71.06 (7.22) years. Widowhood prevalence ranged from 14.1% in the China Health and Retirement Longitudinal Study to 53.9% in Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in South Africa (HAALSI). Spousal loss was associated with poorer memory (multivariable-adjusted β = −0.07, 95% confidence interval [CI]: −0.12 to −0.01) and executive function (multivariable-adjusted β = −0.08, 95% CI: −0.13 to −0.03) in the meta-analysis, with no significant associations for orientation or language. While results were generally consistent in five cohorts, the English Longitudinal Study of Ageing (ELSA) showed divergent patterns (orientation: β = 0.10, 95% CI: 0.06–0.13; memory: β = 0.05, 95% CI: 0.02–0.08; language: β = 0.16, 95% CI: 0.12–0.19). Sex-stratified analyses indicated poorer executive function among men (multivariable-adjusted β = −0.14, 95% CI: −0.19 to −0.08) and poorer memory among women (multivariable-adjusted β = −0.07, 95% CI: −0.14 to −0.01) following widowhood. Nonlinear age-related effects on cognition were observed in ELSA, Longitudinal Ageing Study in India, and HAALSI. Higher education, internet use and body mass index were negatively associated with the risk of cognitive decline among widowed participants.

Spousal loss is associated with domain- and sex-specific differences in cognitive performance, with substantial heterogeneity across study populations. Future research should integrate biopsychosocial markers to develop context-sensitive interventions for widowed older adults.