A - 85 Age-Related Differences in Cognitive Mechanisms: Exploring the Role of Processing Speed in Working Memory and Prospective Memory

Abstract Objective Research links working memory (WM) and prospective memory (PM) on cognitively demanding tasks. Older adults demonstrate more frontal lobe activation than young adults during WM and PM tasks; however, the underlying mechanisms remain unclear. The current study hypothesized processing speed (PS) as a mediator between WM and PM with age cohort as a possible moderator. Method Healthy older adults (n = 80; age 60–89, M = 72.51, SD = 7.08) and young adults (n = 63; age 18–29, M = 19.27, SD = 2.12) were administered WAIS-IV Digit Span, WAIS-IV Coding, and the Virtual Kitchen Protocol for Prospective Memory. Results A moderated mediation model revealed that WM positively influenced PM (c:B = 0.69, p < 0.001) with a positive indirect relationship through PS among older adults (ab:B = 0.26, 95% CI [0.13, 0.43]), but not young adults (ab:B = −0.08, 95% CI [−0.19, 0.03]). Conclusion PS appears to play a significant role in older adults’ use of WM for PM but not in young adults. This could suggest that older adults recruit additional cognitive resources – those involved in PS – as a compensatory strategy for real-world PM tasks, which would support prior research indicating that diminished functioning in older adults results from reduced ability to redirect neurocognitive networks. Alternatively, age-related declines in PS could be a root cause underlying both worse WM and worse PM in older adults, as postulated by Salthouse. Future research would benefit from further differentiating the direction of influences between WM, PS, and PM in older adults.