Does Cognitive Ability Explain Inaccuracy in Older Adults' Self-Reported Medication Adherence?

This study examines the accuracy of younger-old and older-old adults' self-reported adherence over a 3-month period and the potential interactive relationship between self-report accuracy and cognitive abilities. For 3 months, 71 younger-old (M = 68.10, range = 57 to 74) and 62 older-old (M = 80.31, range = 75 to 89) adults had their actual and self-reported adherence monitored. Cognitive tests assessing episodic and prospective memory were given at the beginning of the study. Multilevel models indicate that 32% of the variability in objective adherence was from between-person differences whereas 68% was from within-person fluctuations. There were age differences in the coupling of actual and self-reported adherence over time, such that younger-old adults' self-reports less accurately reflected their actual adherence. Subsequent models indicate that age differences in the coupled relationship were further moderated by cognitive abilities. Results suggest that the relationships among age, cognitive abilities, and accuracy of self-reported adherence are far from simple.