Executive Functions, Processing Speed, and Memory Performance: Untangling the Age-related Effects

Abstract

Age-related decline in memory function is a universal phenomenon. However, several factors are known to affect memory decline associated with aging. The present research aimed to study the differences between young adults and older adults in neurocognitive functions. It also aimed to examine the relative contribution of aging and executive functions to memory performance. The sample consisted of two groups: 43 young adults and 40 older adults. Participants were selected from the community using purposive sampling. Each participant underwent screening using the Edinburgh Handedness Inventory, Modified Mini Screen, and Global Cognitive Screen. A detailed neuropsychological assessment was individually conducted using standardized measures of executive functions, processing speed, episodic memory, and semantic memory. We examined group differences between younger and older participants using the Mann Whitney U test. Additionally, we investigated the contributions of age, processing speed, and executive function to memory through stepwise multiple regression analysis. Analysis of the results suggests significantly worse performance by older participants compared to younger participants on learning and memory (p<.001), semantic memory (p<.001), processing speed (p<.001), and executive functions (p<.001). Our results further indicate that age, processing speed, and executive functions were associated with better performance in learning and memory. However, age emerged as the strongest predictor, followed by processing speed and working memory. Our study demonstrates that aging plays the most significant role in predicting the decline of learning and memory, as well as semantic memory. However, executive functions and processing speed can differentially influence age-associated memory decline. Future studies are warranted on larger populations and more diverse age groups to better comprehend the differential roles of speed, executive functions, and aging on memory performance. We recommend developing age- and education-based normative data for neuropsychological tools specifically tailored to the Indian population.