Neuroanatomical Correlates of Cognitive Reserve in Alzheimer Disease

Abstract

Cognitive reserve (CR), for which formal education represents a proxy index, has been claimed as a factor mitigating the clinical manifestations of Alzheimer disease (AD). The aim of this study was to assess the impact of formal education in modifying the relationship between cerebral grey matter (GM) damage and clinical manifestations in a large cohort of patients with AD or amnesic mild cognitive impairment (a-MCI). We recruited 22 patients with AD and 23 with a-MCI, and we classified them in subjects with high (HEL) or low educational level (LEL). All patients underwent a neuropsychological assessment and magnetic resonance imaging (MRI) scanning at 3T. T1-weighted volumes were analyzed, using voxel-based morphometry, for GM investigation. A 1-year clinical follow-up was available for part of the a-MCI patients. There were no between-groups differences in clinical features, memory, and language functions. Conversely, HEL subjects performed better in all tests assessing visuo-spatial abilities. GM volumes of LEL compared with HEL patients were reduced in the supramarginal gyrus bilaterally and in the right posterior cingulate/precuneus and frontal opercular cortex. Conversely, HEL compared with LEL patients showed reduced GM volumes in the entorhinal cortices and temporal poles, regions typically affected by AD pathology. These results remained unchanged when including in the analysis of only patients with clinically proven AD (AD and a-MCI converters). This study suggests that CR produces selective GM changes that mitigate the clinical impact of AD. Moreover, it supports the idea that CR is based on several "brain reserves" rather than on a generalized increase of brain plasticity.

Cognitive reserve: the evolution of the conceptual framework

“…In particular, by using voxel-based morphometry (VBM), AD patients with high CR (measured as years of formal education) showed significant grey matter atrophy in the entorhinal cortex and in the temporal pole, while less educated AD patients showed widespread atrophy in the supramarginal gyrus, posterior cingulate cortex and precuneus [36]. Moreover, an association between GM volumes and reasoning abilities was found according to the CR levels.…”

“…Previous studies showed several significant interaction effects between levels of CR, CSF-biomarkers (β-amyloid and tau levels), genetic AD-like phenotype (APOE status), brain atrophy and the risk to develop the clinical symptoms of AD [27,[35][36][37][38]. In particular, Jack and co-workers [35] showed that people with a high risk of cognitive impairment due to AD pathophysiological processes, have both APOE 4 and low CR levels.…”

Neural Correlates of Brain Reserve: A Neuroimaging Perspective

“…APOE, b-amyloid levels, brain atrophy, etc.) and the risk to develop the clinical symptoms of AD (Jack et al 2013;Serra et al 2011Serra et al , 2015Soldan et al 2013;Bozzali et al 2014).…”

“…The reserve's hypothesis has been demonstrated in several neurological disorders such as Alzheimer's disease (AD) (Serra et al 2011(Serra et al , 2015Bozzali et al 2014), vascular injury (Elkins et al 2006;Dufouil et al 2003), Parkinson's disease (Glatt et al 1996), traumatic brain injury (Kesler et al 2003), HIV (Farinpour et al 2003) and multiple sclerosis (Sumowski and Leavitt 2013). However AD remains the prototypical model to explain the effect of CR on neuropathology.…”

Efficiency of Cellular Growth When Creating Small Pockets of Electric Current Along the Walls of Cells

“…1 Magnetic resonance imaging (MRI) uses magnetic field in excess of several Tesla to monitor degenerative diseases. 2,3 There is a likely relation between magnetic power and cancer growth. A magnetic field of 50 Hz and 100 microtesla enhanced tumor development and growth in the breast cancer in female Sprague-Dawley rats.…”