Primary School Education May Be Sufficient to Moderate a Memory-Hippocampal Relationship

Abstract

According to the cognitive reserve theory, intellectual stimuli acquired during life can prevent against developing cognitive impairment. The underlying cognitive reserve mechanisms were underexplored in low-educated individuals. Because episodic memory impairment due to hippocampal dysfunction is a key feature of Alzheimer’s dementia (AD), we sought to look at a possible cognitive reserve mechanism by determining whether few years of education moderated the relationship between the hippocampal volumes and the episodic-memory scores. The sample was composed by 183 older adults, 40.1% male, with the median age of 78[76,82] years and the median years of education of 4[2,10] who had undergone an episodic-memory test and a 3-Tesla MRI scan to access the hippocampal volumes. Overall, 112 were cognitively healthy, 26 had cognitive impairment-no dementia (CIND) and 45 had dementia. We used multiple linear regression to assess whether the interaction between years of education and each hippocampal volume significantly predicted the episodic-memory scores’ variance, controlling for cognitive diagnosis and nuisance variables. The interaction term with the left hippocampus (ß = 0.2, p = 0.043, CI = 1.0, 1.4), but not with the right (ß = 0.1, p = 0.218, CI = 0.9, 1.2) significantly predicted the variation on memory scores. The mechanism by which the left hippocampus seems to play a more important role on memory processing in more educated individuals needs to be further investigated and might be associated with a better use of mnemonic strategies or higher hippocampal connectivity. Because the sample’s median years of education was four, which corresponds to primary school, we may infer that this level might be sufficient to contribute for building cognitive reserve.

Moderating effect of cognitive reserve on the association between grey matter atrophy and memory varies with age in older adults

“…However, previous studies of normal aging population found mixed or contradicting results in how educational attainment or proxies of CR alter the association between GMV and cognitive functioning. For example, two studies specifically showed that age‐related GMV variation was positively associated with cognitive functions and such a relationship was stronger in higher CR elderly individuals . Similar or null results were reported in other studies examining the moderating role of CR, showing a stronger association between pathological impact and cognitive functions in higher CR elderly .…”

Hippocampal subregional volume changes in elders classified using positron emission tomography‐based Alzheimer's biomarkers of β‐amyloid deposition and neurodegeneration

“…Also, further analyses of elderly subgroups from LMIC environments stratified according to different levels of educational attainment may reveal other meaningful findings regarding to hippocampal volume variations as a function of number of years of education. For instance, one recent MRI investigation in an elderly sample combining subjects with or without cognitive impairment recruited in a similar LMIC environment showed a significant interaction between larger hippocampal volumes and higher educational attainment predicting better episodic memory performance (Resende et al., 2018). Analyses of HSVs in subsamples of elderly subjects with low educational attainment should also evaluate possible relationships with WMH, in order to verify whether hippocampal tissue may be more prominently affected by microvascular pathology specifically in such elderly subgroups.…”

Environmental and Cognitive Enrichment in Childhood as Protective Factors in the Adult and Aging Brain

“…Various studies have attempted to define the best indicators of CR, considering measures as varied as education, leisure activities and life experiences. The hypothesis is that all of these experiences would model the cognitive networks and enable individuals to cope with brain pathology more or less successfully (Resende et al, 2018).…”