Abstract
BackgroundIt 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.MethodsWe 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.ResultsCompared 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.ConclusionsBoth 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.
Highlights
It remains unclear how executive function (EF) is affected in the stage of amnestic mild cognitive impairment
Perry et al [10] reported specific problems with response inhibition and attention switching in a group of patients who were only impaired on episodic memory tests
With regard to the clinical neuropsychological assessments, ttests showed that the two groups significantly differed on measures of MiniMental State Examination (MMSE), Geriatric Depression Scale (GDS), Auditory Verbal Learning Test (AVLT) and Montreal Cognitive Assessment (MoCA), Table 2 Pearson correlation coefficients for the 5 measures in all participants
Summary
It remains unclear how executive function (EF) is affected in the stage of amnestic mild cognitive impairment (aMCI). The aim of the study was to explore the characteristics of EF impairments in patients with aMCI. AD patients often exhibit various degrees of executive dysfunction [2], but it remains unclear how executive function (EF) is impaired in aMCI [3,4,5,6,7,8,9,10,11,12,13,14,15,16,17]. Perry et al [10] reported specific problems with response inhibition and attention switching in a group of patients who were only impaired on episodic memory tests. In contrast to all these findings, Bisiacchi et al demonstrated preserved EF in aMCI patients compared to normal elderly people [5]
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