A study of validity of a new scoring system of clock drawing test

Objective To set up and verify a new scoring system of clock drawing test(CDT).Methods CDT and other neuropsychological tests were applied to 180 normal individuals.170 subjects with mild cognitive impairment(MCI),and 31 patients with mild Alzheimer's disease(AD).The first step of the system of CDT was to anchor the 4 points of12-3-6-9.totaling a score of 4 which was the 30-score system A(Anchoring)part;and the other 13 items reflecting the drawing results and totaling a score of 26 made up the so called30-score system C(Clockfaee)part.the two together had a total score of 30.Thirty-eight subjects underwent Xe-enhanced computed tomography(Xe-CT)scanning for quantitively measuring regional cerebral blood flow(rCBF)of 26 regions of brain.Results Correlations coefficients of the scores of 14 items with the total score in system of CDT were in the range of 0.48to 0.71(P＜0.01).30-score system C part was closely correlated with indicators of visuospatial and executive function,while system A part with memory indicators.The sensitivity and specificity of the system A part score≤2 for detecting MCl were 70.6%and 73.9%.respectively.The sensitivity the specificity of system C part score≤17 for mild AD were 75.3%and 75.9%.respectively.In the regression equation of system A and C part.the combined independent variables were the CBF of left frontal cortex and right white matter,respectively.Conclusion The system A and C part have difierent meanings:30-score system C part could be used to identify AD while system A part is helpful for identiring MCI. Key words: Alzheimer's disease;  Cognition disorders;  Neuropsychological tests