Level of Executive Function Influences Verbal Memory in Amnestic Mild Cognitive Impairment and Predicts Prefrontal and Posterior Cingulate Thickness

Department of Psychiatry, University of California, San Diego, La Jolla, CA 92037, USA.
Cerebral Cortex (Impact Factor: 8.67). 09/2009; 20(6):1305-13. DOI: 10.1093/cercor/bhp192
Source: PubMed


This study aims to investigate the relationship between executive function and verbal memory and to explore the underlying neuroanatomical correlates in 358 individuals with amnestic mild cognitive impairment (MCI) and 222 healthy controls (HCs). The MCI participants were divided into 2 groups (high vs. low) based on executive function task performance. Results demonstrated that although both MCI groups were impaired on all memory measures relative to HCs, MCI individuals with higher executive function (HEF) demonstrated better verbal memory performance than those with lower executive function (LEF), particularly on measures of learning. The 2 MCI groups did not differ in mesial temporal morphometric measures, but the MCI LEF group showed significant thinning in dorsolateral prefrontal and posterior cingulate cortices bilaterally compared with the MCI HEF and HCs. Further, thickness in numerous regions of frontal cortex, and bilateral posterior cingulate, was significantly associated with memory performance in all MCI participants above and beyond the contribution of the mesial temporal regions known to be associated with episodic memory. Overall, these results demonstrate the importance of evaluating executive function in individuals with MCI to predict involvement of brain areas beyond the mesial temporal lobe.

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    • "MCI individuals with executive dysfunction also have poorer verbal memory performance, suggesting complex interrelationship between memory and executive function.[57] "
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    ABSTRACT: Mild cognitive impairment (MCI) is associated with an increased risk of developing dementia. This is clinically relevant overt dementia can be prevented if treatment strategies are devised for MCI. Neuropsychological deficits in this condition are very common and are important clinically for treatment and outcomes. We aimed to review various neuropsychological deficits in MCI. Further, we have presented the current evidence for nosological status, neuroanatomical basis, and clinical outcome of this heterogeneous construct. All published papers on the topic of neuropsychological deficits in MCI on Medline and other databases were reviewed. A wide range of memory and executive function deficits are common in MCI patients. However, several studies are limited by either improper designs or inadequate sample sizes. Several neuropsychological impairments like memory function and executive functions can be diagnosed in MCI. The evidence base for the exact neuroanatomical basis of MCI is not robust yet. However, given the wide range of outcomes, controversies and debates exist regarding the nosological significance of the deficits. Hence, more studies are needed to specifically locate the impairments and further delineate the construct of MCI.
    Annals of Indian Academy of Neurology 03/2013; 16(3):310-318. DOI:10.4103/0972-2327.116907 · 0.60 Impact Factor
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    • "Many fMRI studies have provided strong evidence that the PFC serves as the most important neural substrate for the three core components of EF in Miyake’s model [36,47,48]. Both the atrophy of the dorsolateral PFC [49] and the impairment of white matter in the frontal lobe [50] have been shown to be related to the decline of EF in aMCI and AD patients. Therefore, pathological changes in the frontal lobe may be the basis of the decrease in all core EF components in aMCI patients. "
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    ABSTRACT: Background It remains unclear how executive function (EF) is affected in the stage of amnestic mild cognitive impairment (aMCI). Previous studies using different methods to assess EF in patients with aMCI have reached inconsistent conclusions. The aim of the study was to explore the characteristics of EF impairments in patients with aMCI. Methods We investigated three core components of EF (i.e., working memory, response inhibition and task switching) based on the theoretical model of EF proposed by Miyake et al. (2000) in 34 aMCI patients and 36 healthy elderly controls using computerized tasks programmed with E-prime (the 2-back task and the keep track task for working memory, the stop-signal task and the Stroop task for response inhibition and the more-odd shifting task for task switching). The overall EF and the three individual EF components were compared between groups. For EF components that were impaired, the extent of impairment was compared using a paired analysis. The aMCI group was further divided into EF-intact and EF-deficit groups according to their performances on the EF tests in clinical neuropsychological assessments. We tested for group differences among the normal controls and the EF-intact and EF-deficit aMCI groups and paid special attention to the comparisons between the EF-intact aMCI group and the control group. Results Compared to the control group, overall EF was significantly impaired in patients with aMCI (Wilks’ λ=0.572,P<0.001). Four tasks (the 2-back task, the keep track task, the stop-signal task and the more-odd shifting task) that tapped the three core components of EF displayed group differences that favored the normal controls. The results of the Stroop task revealed no differences in performance between the two groups. The EF-intact aMCI patients also exhibited significantly impaired capabilities in the four tasks compared to the normal controls. There were no significant differences in the extent of impairment between the four affected tasks in the aMCI group, suggesting that the three core EF components were impaired to the same extent. Conclusions Both the overall EF and all of the core EF components in the Miyake model of EF (working memory, response inhibition and task switching) were significantly impaired in aMCI patients, regardless of whether they had shown obvious clinical executive dysfunction.
    BMC Neurology 11/2012; 12(1):138. DOI:10.1186/1471-2377-12-138 · 2.04 Impact Factor
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    • "In particular, dorsolateral and medial frontal lobe volume loss has been associated with poorer composite scores derived from measures of fluency, setshifting , and response inhibition in MCI (Cardenas et al., 2009). Neocortical thinning in dorsolateral frontal, posterior cingulate, and lateral temporal lobe regions has also been associated with impaired set-shifting and working memory performance (Chang et al., 2009), and decreases in left dorsolateral and medial gray matter concentration has been detected in patients with a dysexecutive subtype of MCI (Pa et al., 2009). These data support previous literature implicating dorsolateral prefrontal regions in executive functioning, but also suggest that executive dysfunction in MCI may be more complex, relying on the integrity of a number of other frontal and posterior cortical regions. "
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    Neurobiology of aging 02/2012; 33(2):242-53. DOI:10.1016/j.neurobiolaging.2010.03.015 · 5.01 Impact Factor
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