The neuropsychological feature of different mild cognitive impairment subtypes

Objective To investigate the neuropsychological features of different mild cognitive impairment (MCI) subtypes. Methods A neuropsychology battery was applied in this study. Seventy MCI participants were enrolled in the test and classified as: 28 amnestic MCI (aMCI), 21 vascular MCI (V-MCI), and 21 Parkinson’s disease MCI (PD-MCI). Forty six normal old people were also evaluated as control. Results First, there were significant differences in the CAMCOG-C and CAMCOG-C subscales of each MCI subtype compared with the normal control. aMCI patients showed significantly impaired orientation, language expression, recent memory, attention, calculation, abstraction and perception（t=4.580,5.150,3.053,4.070,5.918,2.121,2.952,3.175; all P<0.05）. However, the ability of language comprehension, remote memory and execution were relatively reserved. V-MCI patients scored lower in the cognitive function of orientation, language expression, attention and execution compared with the normal control（t=2.974,3.165,4.216,3.197; all P<0.05）, with no significant difference in memory, calculation, abstraction and perception. A boarder cognitive impairment was observed in PD-MCI patients who showed significantly impaired language expression, recent memory, remote memory, learning memory, attention and execution（t=4.433, 3.065, 3.821, 3.447, 5.344, 0.348; all P<0.05）. Second, aMCI (3.07±0.81,11.07±2.28）and PD-MCI(3.00±0.89, 11.33±1.91） patients scored significantly lower in CAMCOG scores and CAMCOG subscales including recent memory and learning memory compared with V-MCI(3.52±0.87,12.48±1.83;aMCI vs V-MCI: t=1.868, 2.381，PD-MCI vs V-MCI: t=1.921, 1.980；all P<0.05）. The remote memory and execution function in PD-MCI were significantly impaired compared to the other two subtypes（PD-MCI vs aMCI: t=2.498,4.257; PD-MCI vs V-MCI: t=1.684, 1.492；all P<0.05）. Third, the GDS scores were different among the four groups. aMCI grouphad significant higher GDS score compared to the normal control group（t=2.850，P<0.05）, while there were no similar changes in V-MCI and PD-MCI groups. Comparing different MCI subtypes with each other, aMCI and V-MCI groups had higher GDS scores than PD-MCI group. Conclusions The features of cognitive impairment in the 3 subtypes are all multiple domains. The characteristic impairment domains are memory in aMCI, executive function in V-MCI, and both memory and executive functions in PD-MCI. aMCI may show greater depression tendency compared to the other two subtypes. The different features in the subtypes of MCI may represent different pathophysiololgical changes in each MCI subtype. Key words: Cognition disorders; Amnesia; Dementia; vascular; Parkinson disease;  Neuropsychological tests