Thesis submitted for the degree of Doctor of Philosophy
Faculty of Medicine, University of London
Department of Epidemiology and Population Health
London School of Hygiene and Tropical Medicine
Background and rationale
Women and the poor are disproportionately affected by common mental disorders (CMD), yet few studies have explored their aetiology in low income countries. Social capital may explain some of the geographical variation in CMD. A systematic review shows that only one study has examined the association between individual social capital and CMD in low income countries. No study has explored the effect of ecological social capital on CMD in this setting. The objective of this thesis is to explore the relationship between individual and ecological measures of social capital and maternal CMD in four low income countries.
Cross-sectional data from the Young Lives (YL) project with information across 234 communities in Peru, Ethiopia, Vietnam and Andhra Pradesh (India) were used. The mental health of caregivers of one-year-old children, and the individual social capital of all caregivers was assessed. Ecological social capital was calculated by aggregating individual responses to the community level. Mothers of one year old children were selected for analysis (n=6909). Multi-level modelling was used to explore the association between individual and ecological social capital in each of the four countries, adjusting for a wide range of individual and community level confounders. Psychometric techniques and qualitative interviews were used in Peru to validate the tool used by YL to measure social capital. Results of these interviews were supplemented with a literature review to explore the nature of social capital in Peru, and analyses were conducted to explore the determinants of social capital. The results of these analyses were used to help interpret the results of a further analysis of the Peruvian data.
The comparative analysis of social capital and CMD across the four countries shows that combined measures of individual cognitive social capital are associated with reduced odds of CMD. The results for structural social capital are more mixed and culturally specific, with some aspects associated with increased odds of CMD. The validation of the tool to measure social capital in Peru emphasises the difficulties of measuring complex concepts in different cultural settings, and illustrates the culturally specific nature of social capital. The description and analysis of social capital in Peru show it to be multi-dimensional and complex and suggest that social capital may have different effects on CMD in different sub-groups.
Conclusions and implications
Contextual and compositional factors are inter-related and are both associated with CMD. Structural social capital has context-specific effects and cognitive social capital more universal effects on CMD. Social capital may have different effects in different sub-groups, with potentially damaging effects in some disadvantaged groups. While social capital is important for mental health, its complex and context-specific nature means that it is impractical to use it as an intervention to prevent or treat CMD. Instead, its value is as a tool for understanding the social context in which the complex relationship between an individual’s own characteristics and those of their environment is played out.