Types of social capital and mental disorder in deprived urban areas: a multilevel study of 40 disadvantaged London neighbourhoods.

OBJECTIVES: To examine the extent to which individual and ecological-level cognitive and structural social capital are associated with common mental disorder (CMD), the role played by physical characteristics of the neighbourhood in moderating this association, and the longitudinal change of the association between ecological level cognitive and structural social capital and CMD. DESIGN: Cross-sectional and longitudinal study of 40 disadvantaged London neighbourhoods. We used a contextual measure of the physical characteristics of each neighbourhood to examine how the neighbourhood moderates the association between types of social capital and mental disorder. We analysed the association between ecological-level measures of social capital and CMD longitudinally. PARTICIPANTS: 4,214 adults aged 16-97 (44.4% men) were randomly selected from 40 disadvantaged London neighbourhoods. MAIN OUTCOME MEASURES: General Health Questionnaire (GHQ-12). RESULTS: Structural rather than cognitive social capital was significantly associated with CMD after controlling for socio-demographic variables. However, the two measures of structural social capital used, social networks and civic participation, were negatively and positively associated with CMD respectively. 'Social networks' was negatively associated with CMD at both the individual and ecological levels. This result was maintained when contextual aspects of the physical environment (neighbourhood incivilities) were introduced into the model, suggesting that 'social networks' was independent from characteristics of the physical environment. When ecological-level longitudinal analysis was conducted, 'social networks' was not statistically significant after controlling for individual-level social capital at follow up. CONCLUSIONS: If we conceptually distinguish between cognitive and structural components as the quality and quantity of social capital respectively, the conclusion of this study is that the quantity rather than quality of social capital is important in relation to CMD at both the individual and ecological levels in disadvantaged urban areas. Thus, policy should support interventions that create and sustain social networks. One of these is explored in this article. TRIAL REGISTRATION: Controlled-Trials.com ISRCTN68175121 http://www.controlled-trials.com/ISRCTN68175121.