[DEX and executive dysfunction in activities of daily living in Alzheimer's disease and frontotemporal dementia]

Abstract

The questionnaire DEX was designed by Wilson et al. in 1996 to explore the disturbances of executive functions (EF) in activities of daily living (ADL).

Objective: This study was performed to explore the specificity of the DEX to evaluate executive dysfunction in ADL, and its contribution to the distinction between Alzheimer's disease (AD) and frontotemporal dementia (FTD).

Subjects: 13 patients with the frontal variant of FTD, 19 patients with FTD associated with amyotrophic lateral sclerosis, FTD/SLA, 18 patients with Alzheimer's disease, AD, and 24 controlled subjects.

Methods: The scores on the DEX completed by a proxy as well as those on two scales assessing ADL (the Cognitive Difficulties Scale by McNair & Kahn, and a composite scale (NADL) including the evaluation of basic (BADL) and instrumental (IADL) by the Lawton & Brody scales, and of social activities (SADL) from Katz & Lyerly) were compared to neuropsychological tests assessing EF (Behavioural Assessment of Dysexecutive Syndrome (BADS), Wisconsin Card Sorting Test, Stroop test, Trail Making Test B, lexical and categorical verbal fluencies, WAIS-III similarities).

Results: No correlation was found between the scores on the DEX or the other ADL scales, and the BADS scores. Scores on DEX showed some weak correlations with some executive tasks, but no stronger than those found with the other ADL scales. Analysis of the most frequently perturbed DEX items failed to show a characteristic profile for EF dysfunction. No significant difference was found between patients with AD and DFT on the scores on the DEX as well as on other ADL scales, when adjusted for dementia severity (assessed by the Mattis Dementia Rating Scale (MDRS)). No difference was found between MA and DFT patients neither in the profile of the most frequently perturbed DEX items, nor in decreased awareness of the disorders assessed by comparison of the scores on the DEX completed by patients and familiars.

Conclusion: In this study, DEX does not appear as a specific tool for assessing EF dysfunction in ADL compared to other ADL scales. It was more related to global cognitive difficulties as assessed by the CDS and the MDRS. Scores on the DEX as well as on other ADL scales do not contribute to the distinction between AD and FTD.