Intraindividual variability in neurocognitive performance is associated with time-based prospective memory in older adults

Introduction: Older adults demonstrate poorer prospective memory (PM) performance than younger adults, particularly for time-based cues and other strategically demanding PM tasks. Intraindividual variability (IIV) in neurocognitive test performance is an index of cognitive control that may be related to the execution of strategically demanding PM tasks. Method: Participants included 194 older Australian adults (age 50 to 88 years) who completed the Memory for Intentions Screening Test (MIST), the Prospective and Retrospective Memory Questionnaire (PRMQ), and clinical measures of executive functions. A measure of naturalistic time-based PM was also administered, in which participants were asked to call the examiner 24 hours after their appointment to report how many hours they slept. IIV was calculated as the mean-adjusted coefficient of variation (CoV) across subtests of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Results: IIV was significantly associated with time-based PM in the laboratory, independent of demographics. Additionally, IIV significantly predicted performance on a naturalistic time-based PM trial, independent of demographics and chronic medical conditions. IIV was not related to event-based laboratory PM or self-reported PM symptoms in daily life. Clinical measures of executive functions were similarly associated with time-based PM and the naturalistic PM task, but not with event-based PM or subjective PM symptoms.Conclusions: These results indicate that cognitive control, as indexed by IIV in neurocognitive performance, may play a role in naturalistic PM, as well as in highly strategic, but not automatic, laboratory-based PM among older adults.