P2-282: Assessment of linguistic measures in neuropsychological testing of MCI: Assessing language components of the Addenbrooke's cognitive examination (ACE)

Detection of early cognitive changes signaling a transition from normal aging to Alzheimer's disease is likely to be important in successful treatment of AD. Much research on cognitive changes focuses on hallmark changes in the memory domain, yet individuals with MCI often exhibit changes in multiple domains. The cognitively comprehensive Addenbrooke's Cognitive Examination-Revised (ACE-R) (Mathuranath) screens multiple domains, including separate assessment of Fluency (letter, semantic) and Language (comprehension, writing, repetition, naming, and reading). Distinguishing between Fluency and Language is important because distinct aspects of language appear to decline independently, as reflected in MCI; e.g., recent evidence of early onset of decline in fluency (both phonemic and semantic) but not in vocabulary (Singh-Manoux, et al 2012). Additionally, recent research indicates association of MCI and a subtle decline in syntactic and semantic factors involved in complex sentence formation, components not tested by ACE-R (Sherman et al, 2011, Lust et al 2011; see also Kemper et al 1993, Almor et al 1999). In this study, we investigate early language changes by comparing results in three populations (amnestic MCI; n = 13, ages 65–80, healthy aging; n = 14, ages 65–80, and young controls; n = 10, ages 20–29) on the ACE-R (overall scores, fluency and language subscores) to results on psycholinguistic tests of syntactic and semantic processing of complex sentences (elicited imitation). Statistical analysis was by a logistic-linear mixed model with binomial error assumption and a logit link function. Results show that while the overall ACE-R scores and ‘fluency’ subscore differ significantly between the young controls and the two aging groups, they do not differ significantly between the two aging groups (healthy and MCI). The ACE-R Language subscore showed no difference across the groups. Psycholinguistic tests of linguistic performance in complex sentences did show a significant difference between Healthy Aging and MCI populations. Regressions of linguistic performance in complex sentences on both ACE-R language and fluency subscores were significant in the Healthy Aging group, and regressions on fluency (but not language) subscores were significant in the MCI group. These findings suggest that attention to psycholinguistic factors may increase our sensitivity to early changes in the language domain in MCI.