Patterns of executive dysfunction in amnestic mild cognitive impairment

Background: Executive dysfunction is not uncommon in patients with amnestic mild cognitive impairment (aMCI). This study aimed to investigate the applicability of executive function tests (EFTs) in aMCI as an aid in establishing the diagnosis of multi-domain MCI. Methods: One hundred and twenty (120) aMCI patients, 126 Alzheimer's disease (AD) patients, and 100 normal controls were enrolled. The EFTs evaluated included the trail making test, digit backward span, Stroop color-word test, and design fluency and category fluency tests. Results: Of the aMCI participants, 66% exhibited impairment in at least one EFT. Among the five selected EFTs, the category fluency test was the most discriminative in detecting executive dysfunction between patients with aMCI (standardized beta = 0.264) or AD (standardized beta = 0.361) with the controls, followed by the Stroop test. The performance of aMCI patients with two or more impaired EFTs was significantly different from those of controls but not from those of AD patients. Conclusion: In the clinical setting, aMCI patients who fail in two or more EFTs may represent a unique population with multi-domain MCI that require close follow-up.