Alzheimer's disease progression based on self-reported cancer history in ADNI
What is it about?
Despite similar cognitive effects experienced between cancer survivors and Alzheimer's disease patients, cancer and Alzheimer's disease have been inversely related in cross-sectional studies. However, no studies have examined how cancer history may affect progression of Alzheimer's disease over time. This manuscript assesses the progression of cognition (using the ADAS-Cog instrument) in Alzheimer's disease patients who have self-reported cancer history and compares this progression to that of Alzheimer's disease patients who did not self-report cancer history. This study was conducted using data from the ADNI study, a longitudinal, observational study of Alzheimer's disease in older adults. We found that after adjustment for relevant covariates, those with mild cognitive impairment and self-reported cancer history exhibited better cognition at baseline than those with mild cognitive impairment and no self-reported cancer history. However, their rate of cognitive progression over time was similar. In Alzheimer's disease patients, we found no difference in cognition at baseline or rate of progression between the self-reported cancer history groups. These results indicate that differences in cognition between those with and without self-reported cancer history occur early in the Alzheimer's disease process. This study has several strengths and several limitations, but overall it seems that clinical trials for Alzheimer's disease should account for cancer history, especially as trials continue to examine Alzheimer's disease early in the disease process.
Why is it important?
This analysis is important because it expounds upon previous cross-sectional research between cancer and Alzheimer's disease by examining the two longitudinally. Also, the results are important as clinical trials in Alzheimer's disease are increasingly being performed earlier in the disease process, even before cognitive symptoms arise. These results indicate that self-reported cancer history may confound associations seen in these trials when not accounted for in analysis of trial data.