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.