Article

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

ABSTRACT

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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    • "The reduced NoGo accuracy findings in the aMCI group were corroborated by the deficits observed on the neuropsychological measures of cognitive control. Overall, the aMCI group performed significantly lesswell compared to the control group not only on neuropsychological measures of episodic memory (logical memory immediate and delayed) but also on measures of cognitive control (Trails B and letter fluency), as has been observed by others[18,20,21,66]. A study by Traykov et al.[22]found that aMCI participants had increased errors during the Stroop interference condition compared to controls, supporting deficits in cognitive control similar to that observed in our NoGo accuracy data. "
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    ABSTRACT: We examined the effects of amnestic mild cognitive impairment (aMCI) on behavioral (response times and error rates) and scalp-recorded event-related potential (ERP) measures of response execution and inhibition, using Go/NoGo tasks involving basic and superordinate semantic categorization. Twenty-five aMCI (16 F; 68.5±8 years) and 25 age- and gender-matched normal control subjects (16 F; 65.4±7.1 years) completed two visual Go/NoGo tasks. In the single car task, responses were made based on single exemplars of a car (Go) and a dog (NoGo) (basic). In the object animal task, responses were based on multiple exemplars of objects (Go) and animals (NoGo) (superordinate). The aMCI subjects had higher commission errors on the NoGo trials compared to the control subjects, whereas both groups had comparable omission errors and reaction times during the Go trials. The aMCI subjects had significantly prolonged N2 ERP latency during Go and NoGo trials across tasks compared to the controls. Both groups showed similar categorization effects and response type effects in N2/P3 ERP latencies and P3 amplitude. Our findings indicate that altered early neural processing indexed by N2 latency distinguishes subjects with aMCI from controls during the Go/NoGo task. Prolonged Go-N2 latency in aMCI appears to precede behavioral changes in response execution, whereas prolonged NoGo-N2 latency underlies behavioral deterioration in response inhibition.
    No preview · Article · Jan 2016 · Journal of Alzheimer's disease: JAD
    • "Tel./Fax: +33 322668240; E-mail: godefroy.olivier@chu-amiens.fr. been reported in AD patients with mild to moderate dementia [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]. In the cognitive domain of executive function, impairments in the performance of the Trail Making, Stroop, and verbal fluency tests are most frequently reported [13] in mild-to-moderate AD. "
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    ABSTRACT: Background: Dysexecutive disorders are common in early-stage Alzheimer's disease (AD) but have yet to be characterized in detail. Objective: The objectives of the present study based on validated diagnostic criteria were to determine the frequency and characterize the profile of behavioral and cognitive dysexecutive disorders in AD. Methods: 102 patients with AD (mild: n = 92; moderate: n = 10; mean MMSE score: 23.2) were examined with the GREFEX battery. Neuropsychological data were interpreted within a validated framework based on the performance levels of 780 control participants from the GREFEX study. Results: Dysexecutive syndrome was observed in 87.5% (95%CI: 79-96) of the AD patients (p = 0.0001). The dysexecutive disorder profile was characterized by prominent impairments of planning, inhibition flexibility and generation in the cognitive domain (p = 0.0001 as compared to controls for all) and global hypoactivity in the behavioral domain (p = 0.0001 as compared to controls). Conclusions: Dysexecutive syndrome is observed in over 80% of AD patients and has a distinct profile.
    No preview · Article · Jul 2014 · Journal of Alzheimer's disease: JAD
    • "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.
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