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


*Megumi Takahashi, MD, PhD, Department of Psychiatry, Kitasato University School of Medicine, 2-1-1 Asamizodai, Sagamihara, Kanagawa 228-8520, Japan. Email: megumita@kitasato-u.ac.jp


Aim:  To investigate the associations of Clock-Drawing Test (CDT) score with neuropsychological test scores and regional cerebral blood flow.

Method:  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.

Results:  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.

Conclusion:  CDT score correlates well with regional cerebral blood flow that is decreased in the early stage of AD.