Title: Chemotherapy for Cancer and the Aging Brain
Description: Purpose: The proportion of the United States population in older adulthood is growing rapidly, and with that growth comes an increase in diseases such as cancer. As rates of illness increase, there is a concomitant increase in cognitive and psychological correlates of illnesses like cancer. There is evidence that some cancer treatments, particularly chemotherapy, affect cognition for cancer patients, although these results are inconsistent. Additionally, depression, and other health factors such as activities of daily living (ADLs) have been found to relate to cognitive impairment among older adults with cancer. Method: The current study used latent class growth analysis (LCGA) to explore longitudinal data from the Health and Retirement Study. The primary goal was to investigate possible trajectories of cognitive functioning in older adults diagnosed with, and surviving cancer. Possible psychological, health, and demographic predictors of membership in these cognitive trajectories were investigated.

Results: Findings indicated that three classes of cognitive functioning best fit the data: these were High Recall, Middle Recall and Low Recall Classes, which represented fairly stable trajectories from pre-diagnosis to a period four years later. Various covariates of class membership were included in the analyses. Treatment with chemotherapy significantly predicted membership in the High Recall Class, however this finding is accounted for by an interaction with younger age. More symptoms of depression after diagnosis (but not prior to diagnosis) were significantly predictive of membership in the Low Recall Class. A higher self-reported probability of living to the age of 85 pre-diagnosis predicted membership in the High Recall Class, and greater difficulty with ADLs post-diagnosis predicted membership in the Low Recall Class. Finally, individuals in the High Recall Class were significantly more likely to be younger, female, and more highly educated, when compared to both the Middle and Low Recall Classes.

Limitations: The current study is limited by the wide spacing of data collection and dearth of sensitive and varied measures of cognitive functioning, which in turn limits the generalizability and specificity of the findings. Additionally, a lack of data on cancer type, staging and treatment variables make more nuanced analysis difficult. It is not possible to generalize these findings to individuals who passed away within two years of their diagnosis, not to individuals of minority status, who were underrepresented in this sample. Conclusions: These results may inform the understanding of cognitive functioning in older adults surviving cancer, as it relates to psychological, demographic and other health factors, with implications for timing and targeting of interventions.