This study investigates the association between dietary fat intake and the risk of incident dementia in the Rotterdam Study, a large population-based prospective study. The study found that high intakes of total fat, saturated fat, and cholesterol were associated with an increased risk of dementia, particularly dementia with a vascular component. Conversely, fish consumption, a major source of n-3 polyunsaturated fatty acids, was inversely related to incident dementia, especially Alzheimer's disease. The study adjusted for various confounding factors, including age, sex, education, and energy intake, and found that the associations remained significant even after further adjustments. The findings suggest that a high intake of saturated fat and cholesterol may increase the risk of dementia, while fish consumption may reduce this risk. The study highlights the importance of dietary factors in the prevention of dementia and underscores the need for further research to confirm these findings. The study was supported by various grants and acknowledges the contributions of numerous individuals and organizations. The results have important implications for public health and dietary recommendations to reduce the risk of dementia.This study investigates the association between dietary fat intake and the risk of incident dementia in the Rotterdam Study, a large population-based prospective study. The study found that high intakes of total fat, saturated fat, and cholesterol were associated with an increased risk of dementia, particularly dementia with a vascular component. Conversely, fish consumption, a major source of n-3 polyunsaturated fatty acids, was inversely related to incident dementia, especially Alzheimer's disease. The study adjusted for various confounding factors, including age, sex, education, and energy intake, and found that the associations remained significant even after further adjustments. The findings suggest that a high intake of saturated fat and cholesterol may increase the risk of dementia, while fish consumption may reduce this risk. The study highlights the importance of dietary factors in the prevention of dementia and underscores the need for further research to confirm these findings. The study was supported by various grants and acknowledges the contributions of numerous individuals and organizations. The results have important implications for public health and dietary recommendations to reduce the risk of dementia.