Stephan, B. C., Matthews, F. E., McKeith, I. G., Bond, J., & Brayne, C. (2007). Early cognitive change in the general population: How do different definitions work?. Journal of the American Geriatrics Society, 55(10), 1534-1540. https://doi.org/10.1111/j.1532-5415.2007.01386.x