Superiority of the Dépistage Cognitif de Québec (DCQ) over the Montreal Cognitive Assessment in differentiating dementia with Lewy bodies from Alzheimer's disease

Abstract

AbstractBackgroundRecent criteria for dementia with Lewy bodies (DLB) are available but early diagnosis remains a challenge since few cases display all core clinical features. Discriminating Alzheimer’s disease (AD) from DLB is also complex given the overlap in cognitive dysfunctions between the two conditions. We aimed to study their differential neurocognitive profile using the Dépistage Cognitif de Québec (DCQ), a newly developed screening tool for atypical dementias. Moreover, we explored whether the DCQ was superior to the Montreal Cognitive Assessment (MoCA) in identifying DLB.MethodsWe compared the performance of 15 patients with DLB to 72 patients with the amnestic variant of AD on the five indexes of the DCQ (Memory, Visuospatial, Executive, Language and Behavioral) as well as the MoCA test, administered in random order. Participants were recruited prospectively in a tertiary memory clinic and diagnosed according to current clinical criteria for AD and DLB.ResultsThere were no significant differences between the groups in age (AD: 72.97; DCL: 72.13) or level of education (AD: 12.88; DCL: 12.40). Mean Total MoCA score was similar across conditions (19.01 vs 20.00, p = .54) whereas the Total DCQ score revealed a significant difference between AD and DLB (66.39 vs 72.60, p < .05) (Fig. 2). Further analyses showed superior Area Under the Curve for the DCQ (69.23%; moderately strong) over the MoCA (55.26%; weak) in discriminating DCL from AD (Fig. 1). Bivariate analyses on the DCQ and MOCA indexes were performed using Wilcoxon‐Mann‐Whitney tests. When compared to AD, DLB participants performed worse on the Visuospatial Index (5.04 vs 4.10, p < .05) (Fig. 4), particularly the visuospatial construction task (1.33 vs 0.67 p < .05) while AD participants were significantly more affected on the Memory Index (recall and recognition) (16.13 vs 24.73, p < .0001) (Fig. 3). The remaining DCQ indexes (Executive, Language and Behavioral) were similar between groups.ConclusionsOur data suggests that the DCQ may be a superior tool than the MoCA in distinguishing AD from DLB. The DCQ allowed better characterization of the neurocognitive profile between AD and DLB, where DLB preferentially affects visuospatial skills while AD targets memory abilities.