Objective: The aim of this study was to compare two screening methods, total score of the Cognitive Abilities Screening Instrument (CASI ) and the combined score for the short-term memory and orientation domains (CASI ) for screening and grading probable Alzheimer's disease (AD), based on their correlations with voxel-based morphometry (VBM). Materials and methods: Forty-five subjects with probable AD and normal controls underwent magnetic resonance imaging and CASI testing. Their corresponding T1-weighted magnetic resonance images were analyzed using VBM. Results: VBM results showed that in moderate-to-severe AD subgroups, significant whole-brain gray matter loss was detected using both CASI and CASI . Significantly more voxels were detected using the CASI compared with the CASI system in mild AD subjects (P<.05). Conclusions: Based on their correlations with VBM results, there is no significant difference for CASI and CASI for grading moderate-to-severe AD subgroups, and CASI scoring system may be more accurate and effective than the CASI for screening mild AD. © 2012 Elsevier Inc.