Poor performance in Clock‐Drawing Test associated with visual memory deficit and reduced bilateral hippocampal and left temporoparietal regional blood flows in Alzheimer's disease patients

Abstract

To investigate the associations of Clock-Drawing Test (CDT) score with neuropsychological test scores and regional cerebral blood flow. Twenty-five patients (normal aging, n = 2; mild cognitive impairment, n = 7; Alzheimer's disease [AD], n = 16) participated in this study. Their average age was 74.8 years. CDT score correlated well with the neuropsychological test scores of Mini-Mental State Examination, Clinical Dementia Rating, immediate visual memory, delayed visual memory, and IQ evaluated by Koh's block design. CDT score also had a statistically significant correlation with the regional blood flow in the left hippocampal region as evaluated on 3-D stereotaxic region-of-interest template analysisapplied to single-photon emission computed tomography images. Using a cut-off point of 8/9 in the CDT, the high-CDT group had significantly higher delayed visual memory and IQ scores than the low-CDT group. Moreover, the high-CDT group had significantly higher regional blood flows in the left parietal, left angular and bilateral hippocampal regions than the low-CDT group. CDT score correlates well with regional cerebral blood flow that is decreased in the early stage of AD.