Kana Pick-out Test and brain perfusion imaging in Alzheimer's disease

Background: The Kana Pick-out Test (KPT), which was developed in Japan, is suitable for evaluating frontal lobe function and screening for mild dementia. However, the neural substrates involved remain to be elucidated. The aim of the present study was to identify the regional perfusion patterns in the brain associated with performance scores on the KPT in patients with mild Alzheimer's disease (AD), using brain perfusion assessed by single photon emission computed tomography (SPECT). Methods: Twenty AD patients with high scores on the KPT and 20 age-and sex-matched AD patients with low scores were selected from 227 consecutive Japanese patients of the Memory Clinic of Okayama University Hospital. All 40 subjects underwent brain SPECT with 99mTc-ethylcysteinate dimer, and the SPECT images were analyzed by Statistical Parametric Mapping. Results: With the exception of KPT scores, no significant differences were found between high and low scoring groups with respect to Addenbrooke's Cognitive Examination scores, Mini-mental State Examination scores, or the depression score of the Neuropsychiatric Inventory subscale. Compared to patients with high scores on the KPT, AD patients with low scores on the KPT showed significant hypoperfusion in the left subgenual cingulate gyrus (SGC) extending to the right SGC. Conclusions: Our results suggest that functional activity of the SGC is closely related to scores on the KPT. KPT might be a promising strategy to use in detecting early stages of AD with low SGC function.