The recognition of dementia as a multifactorial disorder encourages the exploration of new pathways to understand its origins. Social health might play a role in cognitive decline and dementia, but conceptual clarity is lacking and this hinders investigation of associations and mechanisms. Social health might provide a new perspective on social connectedness. The objective is to develop a conceptual framework for social health to advance conceptual clarity in future studies and to identify potentially modifiable risk and protective factors in the “Social Health And Reserve in the Dementia patient journey (SHARED)” project.

The methods include the process of building the conceptual framework. We used the following steps: underpinning for concept advancement, concept advancement by the development of a conceptual model, and exploration of its potential feasibility.

Underpinning of the concept drew from a synthesis of theoretical, conceptual and epidemiological work, and resulted in the definition of social health as well-being that relies on capacities both of the individual and the social environment. In the conceptual framework the abstract definition has been elaborated into more precisely defined domains at both the individual and the social environmental levels. This allowed to identify domain related social health characteristics or markers in epidemiological data bases and to investigate associations between these markers and cognitive decline and dementia. The associated social health markers represent potentially modifiable risk and protective factors. Examples are “social engagement” in the participation domain at the individual level, and “frequency of contact” in the structure domain, “exchange of support” in the function domain and “loneliness” in the appraisal domain at the environmental level. The conceptual framework facilitated identification of domain related markers in the SHARED project, thus showing its potential feasibility.

The conceptual framework provides guidance for future research and facilitates identification of potentially modifiable risk and protective factors. These may shape new avenues for preventive interventions. We highlight the paradigm of social health in dementia as a priority for dementia research.

Cerebrovascular disease is regarded as a potential cause of late-life depression. Yet, evidence for associations of neuroimaging markers of vascular brain disease with depressive symptoms is inconclusive. We examined the associations of neuroimaging markers and depressive symptoms in a large population-based study of middle-aged and elderly persons over time.

A total of 4943 participants (mean age = 64.6 ± 11.1 years, 55.7% women) from the Rotterdam Study were included. At baseline, total brain volume, gray matter volume, white matter volume, white matter hyperintensities volume, cortical infarcts, lacunar infarcts, microbleeds, white matter fractional anisotropy, and mean diffusivity (MD) were measured with a brain MRI (1.5T). Depressive symptoms were assessed twice with the Center for Epidemiologic Studies Depression scale (median follow-up time: 5.5 years, IQR = 0.9). To assess temporal associations of neuroimaging markers and depressive symptoms, linear mixed models were used.

A smaller total brain volume (β = −0.107, 95% CI −0.192 to −0.022), larger white matter hyperintensities volume (β = 0.047, 95% CI 0.010–0.084), presence of cortical infarcts (β = 0.194, 95% CI 0.047–0.341), and higher MD levels (β = 0.060, 95% CI 0.022–0.098) were cross-sectionally associated with more depressive symptoms. Longitudinal analyses showed that small total brain volume (β = −0.091, 95% CI −0.167 to −0.015) and presence of cortical infarcts (β = 0.168, 95% CI 0.022–0.314) were associated with increasing depressive symptoms over time. After stratification on age, effect sizes were more pronounced at older ages.

Neuroimaging markers of white matter microstructural damage were associated with depressive symptoms longitudinally in this study of middle-aged and elderly persons. These associations were more pronounced at older ages, providing evidence for the role of white matter structure in late-life depressive symptomatology.

The coronavirus disease-2019 (COVID-19) pandemic and accompanying lockdown restrictions impacted social life significantly. We studied associations of sociodemographic factors, mental and social health markers, and brain structure with social health trajectories during the COVID-19 pandemic.

Prospective longitudinal population-based cohort study.

Community-dwelling inhabitants of Rotterdam, the Netherlands.

Repeated questionnaires including questions on social health were sent to Rotterdam Study participants from April 2020 onwards. Social health data at study baseline were available for 5017 participants (mean age: 68.7 ± 11.3; 56.9% women).

Determinants were assessed in routine Rotterdam Study follow-up (1990–2020), including global brain volumes in a subset of participants (N = 1720). We applied linear mixed models and generalized estimating equations to quantify associations between determinants and trajectories of loneliness, perceived social isolation and social connectedness over three time points from April 22nd to July 31st 2020.

Loneliness prevalence was 27.9% in April 2020 versus 12.6% prepandemic. Social isolation (baseline mean 4.7 ± 2.4) and loneliness scores (baseline mean 4.9 ± 1.5) decreased over time, whereas social connectedness trajectories remained stable. Depressive symptoms, female sex, prepandemic loneliness, living alone, and not owning a pet were independently associated with lower social connectedness and higher social isolation and loneliness at COVID-19 baseline, but recovery of social health was similar for all determinants. Larger intracranial volume was associated with higher social connectedness.

Despite baseline differences for specific determinants, older adults showed similar recovery of loneliness and social isolation alongside stable social connectedness over time during the pandemic. Social health is multidimensional, especially during a global health crisis.