Longitudinal associations between cancer history and cognitive functioning among older adults

Objectives: This study aimed to examine (1) whether cancer history accelerates older adults' rates of cognitive decline over time and (2) whether chemotherapy increases older cancer patients'/ survivors' rates of cognitive decline over time. Methods: This longitudinal study drew a subsample of 8811 adults aged 65 or older from Wave 6 of the Health and Retirement Study in 2002 and followed biennually until Wave 13 in 2016. Linear mixed-effects models were performed to test whether cancer history and chemotherapy were associated with accelerated rates of cognitive decline over time among older adults in different age groups. Results: Middle-old adults (aged 75-84) with a cancer history had significantly reduced rates of cognitive decline over time, including the global measure of cognitive functioning (B = 0.16, p< .01), mental status (B = 0.08, p< .01), and episodic memory (B = 0.09, p< .05) compared to their counterparts without a cancer history. This effect was not significant for the youngest-old (aged 65-74) or oldest-old adults (aged 85 or older). Also, chemotherapy was not significantly associated with older cancer patients'/survivors' cognitive functioning at baseline or over time in different age groups. Conclusions: This study finds that cancer history and chemotherapy do not further exacerbate older adults' cognitive functioning over time. On the contrary, cancer history shows a "protective" effect on middle-old adults' cognitive functioning. This encouraging finding indicates that older adults can be more actively engaged in the decision-making of treatments and following care plans. Future mediation studies are needed to further investigate underlying mechanisms.