Sentence processing in mild cognitive impairment

Difficulties in sentence processing have been reported in patients with Mild Cognitive Impairment (MCI), which may be due to impairment in primary syntactic abilities or short-term memory. In the present study, we investigated the relationship between overt sentence production (SP) and comprehension (SC) with short-term memory performance in MCI. Cognitively healthy elderly (n = 34), amnestic MCI (aMCI,n = 22), non-amnestic MCI (naMCI,n = 45), and Alzheimer's disease (AD,n = 18) patients were asked to complete tests of constrained SP and oral SC. We tested the association between performance in SP and SC with memory tasks and performed a qualitative analysis of the frequency and type of errors in SC. Our results showed that there were no intergroup differences in SC and SP performances. SC scores were associated with delayed recall for words in the naMCI group (p = 0.003), and immediate (p = 0.001) and delayed recall for shapes (p = 0.031) in AD. There were no predictors for NAT scores in any group. In conclusion, the three groups performed similarly in SC and SP tasks. Short-term memory was not associated with performance in the SP task. There was an association between performance in the SC task and verbal memory in naMCI and non-verbal memory in AD; the latter may reflect visuospatial processing demands embedded in the SC task.