Case-control studies of risk factors for Alzheimer's disease have been hampered by low statistical power. Here, we present a collaborative analysis of 11 case-control studies of Alzheimer's disease. The original data of these studies were pooled and re-analyzed. The risk factors considered in this analysis were family history of dementia and related disorders, maternal age at index birth, head trauma, medical and psychiatric history and environmental exposures. This paper gives a brief overview of the findings of the re-analysis.