Executive dysfunction and gray matter atrophy in amnestic mild cognitive impairment

Abstract

Recent studies have shown that impairment in executive function (EF) is common in patients with amnestic mild cognitive impairment (aMCI). However, the neuroanatomic basis of executive impairment in patients with aMCI remains unclear. In this study, multiple regression voxel-based morphometry analyses were used to examine the relationship between regional gray matter volumes and EF performance in 50 patients with aMCI and 48 healthy age-matched controls. The core EF components (response inhibition, working memory and task switching, based on the EF model of Miyake et al) were accessed with computerized tasks. Atrophic brain areas related to decreases in the three EF components in patients with aMCI were located in the frontal and temporal cortices. Within the frontal cortex, the brain region related to response inhibition was identified in the right inferior frontal gyrus. Brain regions related to working memory were located in the left anterior cingulate gyrus, left premotor cortex, and right inferior frontal gyrus, and brain regions related to task shifting were distributed in the bilateral frontal cortex. Atrophy in the right inferior frontal gyrus was most closely associated with a decrease in all three EF components in patients with aMCI. Our data, from the perspective of brain morphology, contribute to a better understanding of the role of these brain areas in the neural network of EF.

Convergent Results from Neuropsychology and from Neuroimaging in Patients with Mild Cognitive Impairment

“…Furthermore, TMT B predicted variation in the middle temporal cortex on trend level, which is in line with previous findings [30]. TMT B relies on both working memory and task switching ability [35], functions subserved by regionally distributed brain regions [37,53,54]. …”

“…While verbal memory has been reliably coupled with MTL integrity [41], executive function measured by TMT B performance has been associated with cortical thickness in frontal, temporal and parietal brain regions [37,53,54]. Since several studies have delineated the utility of RAVLT and TMT B, and these tests are readily available to the clinician [28,29,38,39], we were interested in how they compared to a composite test score as predictors of variance in the 2 neuroimaging modalities.…”

Revisiting the Continuum Hypothesis: Toward an In-Depth Exploration of Executive Functions in Korsakoff Syndrome

“…Centrally, three research axes are proposed:

Using specific EF tasks: future studies should use tasks evaluating each basic EF components (updating, shifting, and inhibition), e.g., the nine Miyake’s tasks (Miyake et al, 2000; see Figure 1B) which have been found to specifically explore the distinct EF subcomponents. The validity of these tasks has been reinforced by studies confirming the underlying multi-factorial model of EF in various healthy samples (Hedden and Yoon, 2006; Vaughan and Giovanello, 2010; Zheng et al, 2014). Although Miyake’s tasks have not yet been applied to psychiatric population, they are now widely used to explore EF (Fournier-Vicente et al, 2008) and present higher sensitivity and lower ceiling effect than classical EF tasks.

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“…The validity of these tasks has been reinforced by studies confirming the underlying multi-factorial model of EF in various healthy samples (Hedden and Yoon, 2006; Vaughan and Giovanello, 2010; Zheng et al, 2014). Although Miyake’s tasks have not yet been applied to psychiatric population, they are now widely used to explore EF (Fournier-Vicente et al, 2008) and present higher sensitivity and lower ceiling effect than classical EF tasks.…”

Retained executive abilities in mild cognitive impairment are associated with increased white matter network connectivity

“…We describe how alterations in the network of white matter connections in the brain relate to differences in executive abilities found in individuals with MCI. Although executive abilities and MCI have previously been linked using DTI [11], the use of network measures to describe this relationship is not well characterised in the literature.…”