Executive dysfunction and periventricular diffusion tensor changes in amnesic mild cognitive impairment and early Alzheimer's disease

Abstract

Our aim in this study was to explore the neural substrates of executive function in frontal and nonfrontal white matter using diffusion tensor imaging (DTI). We studied the relationship between executive dysfunction and DTI measurements on 13 subjects with amnesic mild cognitive impairment (aMCI), 11 subjects with early Alzheimer's disease (AD), and 16 control subjects. All participants underwent an examination of their intelligence, memory, and executive function and were subjected to DTI. Both aMCI and early AD subjects showed executive function impairment with differential performance in frontal-related behaviors. Both aMCI and early AD subjects showed increased mean diffusivity in the genu of the corpus callosum and left frontal periventricular white matter (PVWM), whereas subjects with early AD showed an additional decrease in the fractional anisotropy of bilateral frontal PVWM and in the genu of the corpus callosum. The frontal PVWM was associated with performance on the Verbal Fluency Test, the Wisconsin Card Sorting Test (WCST), and Part B of the Trail Making Test. The parietal PVWM was associated with perseverative errors on the WCST and Part A of the Trail Making Test. In summary, executive function was impaired in subjects with aMCI and early AD and was associated with frontal and parietal PVWM changes. These changes may be due to early AD degeneration of the lateral cholinergic projections or to early change of the superior longitudinal fasciculus.

Magnetic resonance imaging of leukoencephalopathy in amnestic workers exposed to organotin

“…There is a growing body of evidence suggesting that active white matter degeneration underlies amnestic mild cognitive impairment (Rowley et al, 2013, Chen et al, 2009Gouw et al, 2008;Duan et al, 2006;Liu et al, 2013).…”

Atlas-Based Diffusion Tensor Imaging Correlates of Executive Function

“…However, the analysis was not stratified by group. Chen, et al [43] examined the associations between FA and MD in the periventricular white matter (PVWM) and EF performance. They found that frontal PVWM was associated with performance on a verbal fluency test, the Wisconsin Card Sorting Test (WCST), and TMT B, while parietal PVWM was associated with perseverative errors on the WCST and TMT A.…”

Decreased White Matter Integrity in Neuropsychologically Defined Mild Cognitive Impairment Is Independent of Cortical Thinning

“…Within individual ROIs, the MCI group showed decreased FA in WM underlying the entorhinal, but not parahippocampal, cortex. Other studies have identified decreased WM integrity in parahippocampal WM in MCI (Liu et al, 2009; O'Dwyer et al, 2011; Rose et al, 2006; Zhang et al, 2007). One possible explanation for this discrepancy is that our sample may represent early MCI, as these are individuals who were neurologically normal per history, identified only by neuropsychological status.…”

“…WM integrity within posterior brain regions, most notably the posterior cingulate, is also related to memory (Delano-Wood et al, 2012; Fellgiebel et al, 2005; Rose et al, 2006; Walhovd et al, 2009). The importance of parietal WM to executive functioning in MCI has also been suggested (Chen et al, 2009; Jacobs et al, 2012; Kim et al, 2011). Because multiple studies show strong relationships between cortical thickness and cognition (Chang et al, 2010; Fjell et al, 2008; Walhovd et al, 2009), it is important to determine whether relationships between cognition and WM integrity are independent of cortical thinning.…”

“…Studies investigating specific cognitive domains have provided initial evidence that decreased WM integrity correlates with memory (Bosch et al, 2012; Goldstein et al, 2009; Walhovd et al, 2009) and executive functioning in MCI (Chen et al, 2009; Grambaite et al). WM integrity within posterior brain regions, most notably the posterior cingulate, is also related to memory (Delano-Wood et al, 2012; Fellgiebel et al, 2005; Rose et al, 2006; Walhovd et al, 2009).…”