A Commentary on

Knorst J K, Menegazzo G R, Emmanuelli B, Mendes F M, Ardenghi T M.

Effect of neighborhood and individual social capital in early childhood on oral health-related quality of life: a 7-year cohort study. Qual Life Res 2019; DOI:10.1007/s11136-019-02138-4.

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Commentary

Social capital can be defined as 'networks together with shared norms, values and understandings that facilitate co-operation within or among groups'.1 Health may be improved by social capital in a number of ways. 'Bonding' social capital refers to close ties that can help mitigate the strains of life.2 An example might be a family member bringing an older relative to a dental appointment. These close relationships can reduce stress and loneliness, which are in themselves health damaging, but may also increase the likelihood of adverse coping behaviours, such as smoking and drinking. Looser ties between groups from different backgrounds is known as 'bridging' social capital.2 This can promote trust and aid beneficial transfer of information, such as job opportunities. An example might be between members of a voluntary group. 'Linking' social capital refers to links between individuals and groups at different levels in the social or power hierarchy; opening up resources and opportunities to less powerful or excluded groups.3 Examples include relationships between funders and community interest groups, or formal mentorship arrangements.

A recent systematic review and meta-analysis found a 'modest positive relationship' between social capital and self-reported 'good health' and mortality outcomes.4 There is a growing body of literature investigating links between social capital and oral health, which have so far shown mixed results.5 One of the key difficulties faced by investigators is how to accurately measure such a complex social concept.4,5 Additionally, many previous studies have not accounted for important confounders, and there has been a lack of longitudinal studies.4 Longitudinal studies are needed because it is impossible to say from cross-sectional studies which direction any relationship is operating in; that is, it could be that poor health reduces social participation, rather than the other way around. This study adds to the literature and benefits from a prospective design with a population-based sample, relatively long duration of follow-up and good retention rates. The analysis also accounted for the confounding effect of socio-economic factors and reason for last dental attendance. The results are interesting and provide some evidence of an association between social capital and oral health in Brazilian children.

In the UK context, a recent prospective cohort study found that lower social capital at baseline was associated with greater deterioration in OHRQofL in older adults after five years.6 However, as with all observational studies, it must be remembered that association does not necessarily mean causation. It may be possible that measures of social capital correlate with other important but unmeasured confounders. Well-controlled intervention studies aimed at increasing neighbourhood or individual social capital are needed to provide stronger evidence of causation. Recent initiatives underpinned by theory and research on social capital include the 'social prescribing' movement, whereby general medical practices create formal links with community and voluntary organisations for the benefit of their patients.7,8 This is an area of growing interest and shows the potential for dental practices to link into such networks in an exciting, but relatively unexplored area.