Lifecourse Perspectives on Dementia Epidemiology: Are We Studying Alzheimer's Disease or Child Development?
Dementia poses a tremendous public health burden, but the major causes of dementia remain controversial. Identifying modifiable causes of dementia is challenging because of ambiguity in the outcome definition, the long and insidious onset of disease, and substantial confounding. I argue that many of the risk factors identified in observational epidemiology are correlates of childhood development, rather than causes of neurodegenerative diseases such as Alzheimer's disease, which emerge in old age. If so, recent trends in dementia incidence should be interpreted in light of improved childhood conditions in the first half of the 20th century. To advance our understanding of Alzheimer's disease and related disorders, we will need novel study designs that circumvent the measurement and confounding biases intrinsic to research on dementia