Background: A substantial literature exists that demonstrates associations between putative risk factors and cognitive decline in late life. However, there is a need to integrate this broad literature within a framework that incorporates the interaction of behavioral and ecological influences with cognitive development. Such a framework is required for developing a range of personal and environmental interventions to optimize cognitive development in the population, and to reduce the risk of cognitive impairment in late life.
Objective: This review aims to identify the key considerations for developing a life course model of the various factors that influence cognitive development and cognitive decline. A contextualized, dynamic approach to life course epidemiology is proposed.
Methods: A theoretical evaluation of key methodological and interpretational issues relating to how risk factors influence cognitive development and cognitive impairment was conducted. This focused on the example of alcohol consumption as a risk factor for cognitive decline and dementia.
Results: This review identified dimensions that need to be accounted for in life course theories of cognitive development and cognitive impairment. These include: (a) intergenerational influences; (b) methodological and interpretational issues; (c) individual differences (personal factors); (d) contextual factors (environmental or ecological factors), and (e) cognitive ability as determinant. The methodological and interpretational factors included measurement of exposure and outcome variables; the important distinction between level of ability versus change over time; nonlinear relationships among exposures and outcomes, and outcomes and age; the distinction between association and cause, and between short-term effects and long-term change.
Conclusion: A contextualized, dynamic approach to life course epidemiology accounts for the complex range of influences over the life course that interact to determine normal and pathological cognitive ageing. This approach provides a framework for the development of interventions to maximize cognitive gains in early life, and minimize cognitive loss in late life.
Copyright 2008 S. Karger AG, Basel.