Abstract
Objective: To examine whether educational attainment, as a proxy of cognitive reserve, moderated the association between hippocampal volumes and episodic verbal memory performances in healthy older adults.Methods: Data from 76 community dwelling older adults were included in the present study. Measures of hippocampal volumes (total, left, and right) were obtained using FreeSurfer software. Immediate and delayed verbal recall scores were derived from performances on the California Verbal Learning Test-Second Edition and the Wechsler Memory Scale- Third Edition. Educational attainment was defined by years of education. Linear regression analyses were performed using immediate and delayed recall as dependent variables and hippocampal volumes, years of education, and their interaction terms as independent variables. All analyses were controlled for age, sex, depression, and health status.Results: Total and left Hippocampal volumes had a positive main effect on delayed recall only. Additionally, the interaction between total, left, and right hippocampal volumes and education was a significant predictor for delayed recall performance but not for immediate recall performance. The positive association between hippocampal volumes and delayed recall was greatest in those with more years of education.Conclusion: Larger hippocampal volumes were associated with better delayed verbal recall and the effect on delayed recall was greatest in those with more years of education. Having higher levels of education, or cognitive reserve, may enable individuals to capitalize on greater structural integrity in the hippocampus to support delayed recall in old age. However, longitudinal research is needed to investigate the directionality of these associations.
Highlights
The relationship between advanced age and cognitive decline has been well documented since the beginnings of mental testing in adults (Foster and Taylor, 1920)
Decades of research has shown that episodic memory is a complex ability involving multiple neural structures, the hippocampus is one of the most well established brain structures involved in episodic memory function (Scoville and Milner, 1957; Markowitsch, 1995; Vargha-Khadem et al, 1997; Desgranges et al, 1998; Squire and Zola, 1998; Tulving and Markowitsch, 1998; Burianova and Grady, 2007; Travis et al, 2014; Gorbach et al, 2017)
Alzheimer’s disease (AD) exemplifies the critical role of the hippocampus in memory functioning; AD pathology is characterized by marked hippocampal atrophy in the early stages which correlates to concomitant episodic memory impairment (Bäckman et al, 2001; Kramer et al, 2004; Dubois et al, 2007; Hirni et al, 2013; Tromp et al, 2015)
Summary
The relationship between advanced age and cognitive decline has been well documented since the beginnings of mental testing in adults (Foster and Taylor, 1920). Some cross sectional and longitudinal studies have shown positive associations between episodic memory performance and hippocampal volume (Walhovd et al, 2004; Murphy et al, 2010). These findings would seem to suggest that larger hippocampal volumes are better for memory function. Contrary evidence that smaller hippocampal volumes are positively associated with episodic memory has been found in healthy young adults (Chantome et al, 1999; Foster et al, 1999) Such evidence points to a dynamic relationship between hippocampal volumes and memory across the lifespan which is consistent with other research (Raz et al, 1998). While the author suggested that methodological factors such as impact of statistical methods and individual differences in participant characteristics across samples may account for this variability, there may be other moderating factors
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
