Prospective memory partially mediates the association between aging and everyday functioning

Abstract

Objective: Older adults commonly experience declines in everyday functioning, the reasons for which are multifactorial. Prospective memory (PM), or remembering to carry out intended actions, can be an executively demanding cognitive process that declines with older age and is independently associated with a variety of everyday functions (e.g. taking medication). This study examined the hypothesis that PM mediates the relationship between older age and poorer everyday functioning.Method: A total of 468 community-dwelling adults (ages 18-75) with a range of medical comorbidities (e.g. viral infection) were classified as dependent on four well-validated measures of manifest everyday functioning: activities of daily living, employment status, the Karnofsky Scale of Performance Status, and self-reported cognitive symptoms. Participants completed the Memory for Intentions Test (MIsT) to measure PM, alongside clinical tests of executive functions and retrospective memory.Results: Controlling for education and comorbidities, bootstrap analysis revealed a significant direct effect of age on everyday functioning and a significant mediated effect of age on everyday functioning through the indirect effect of time-based b = .006 [.003, .010] and event-based PM (b = .005, [.002, .009]), as well as slightly smaller effects for executive functions (b = .003, [.001, .005]) and retrospective memory (b = .002, [.001, .005]).Conclusions: These cross-sectional data suggest that executively demanding aspects of declarative memory play an important partial mediating role between an individual factor (i.e. age) and daily life activities, and highlight the possible benefit of targeting PM for improving everyday functioning in older adults.

Keywords: Mediation; activities of daily living; cognition; executive functions; older adults.

Figure 1.

Univariate (unadjusted) r_s association between age and everyday functioning domains impaired.

Figure 2.

Mediation model with unstandardized bootstrap estimates and 95% confidence interval values for age and everyday functioning mediated by (A) time-based PM scores and (B) event-based PM scores.

Figure 2.

Mediation model with unstandardized bootstrap estimates and 95% confidence interval values for age and everyday functioning mediated by (A) time-based PM scores and (B) event-based PM scores.

Figure 3.

Fully standardized mediated effect sizes between age and four separate everyday functioning variables (activities of daily living, Karnofsky scale of performance status, Profile of Mood States confusion-bewilderment scale, and employment status) across different mediators (time-based prospective memory, event-based prospective memory, executive functions, retrospective memory). Note. ADL = Lawton & Brody Activities of Daily Living number of domains impaired; Karnofsky = Karnofsky Scale of Performance Status raw scores; POMS C/B = Profile of Mood States confusion/bewilderment scale age- and gender-adjusted z-scores; Employment = employment status as “unemployed” or “disabled.” Effect size for employment was computed using mean and SD of a point biserial variable in order to compare across everyday functioning measures. Error bars indicate 95% confidence interval for each effect size.