Reliability and validity of A Quick Test of Cognitive Speed for detecting early-stage dementia in elderly Japanese.
OBJECTIVE
The aim of this study was to evaluate the reliability and validity of A Quick Test of Cognitive Speed (AQT) for detecting early-stage dementia in the elderly Japanese population.


METHODS
A total of 280 clinical participants (180 with mild Alzheimer's disease, 43 with amnestic mild cognitive impairment, 32 with non-amnestic mild cognitive impairment and 25 control subjects) and 22 community-dwelling elderly individuals without dementia were recruited. The Clinical Dementia Rating, the Mini-Mental State Examination, and AQT were administered to all participants. The Neurobehavioral Cognitive Status Examination was also administered to clinical participants.


RESULTS
The intraclass correlation coefficient for the test-retest reliability of colour-form naming time on AQT was 0.88 (95% CI, 0.74-0.95, P < 0.001). AQT colour-form naming time was significantly correlated with the Clinical Dementia Rating, the total score on the Mini-Mental State Examination, and the total score on the Neurobehavioral Cognitive Status Examination and most of its subscales. AQT colour-form naming time was significantly longer in elderly individuals with mild Alzheimer's disease, amnestic mild cognitive impairment, and non-amnestic mild cognitive impairment than in control subjects. The receiver operating characteristic curve analysis indicated that AQT colour-form naming time significantly distinguished subjects with early-stage dementia (mild Alzheimer's disease, amnestic mild cognitive impairment, and non-amnestic mild cognitive impairment) from controls. The area under the curve was estimated to be 0.88 (95%CI = 0.82-0.95). A cut-off of 71/72 seconds yielded the best sensitivity/specificity trade-off: sensitivity = 85% and specificity = 76%.


CONCLUSIONS
AQT is a useful brief screening tool for detecting early-stage dementia in elderly Japanese individuals.
Division of Psychiatry, Medical Center for Dementia, Sendai City Hospital, Sendai, Miyagi, Japan.
Fumi
F
Takahashi
Shuichi
S
Awata
Naoko
N
Sakuma
Hiroki
H
Inagaki
Mutsuo
M
Ijuin
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000523:psychology; D000647:Amnesia / Q000175:diagnosis* / Q000523:psychology; D060825:Cognitive Dysfunction / Q000175:diagnosis* / Q000523:psychology; D003118:Color Perception; D003431:Cross-Cultural Comparison; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000706:statistics & numerical data; D008609:Mental Status Schedule / Q000706:statistics & numerical data; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D010364:Pattern Recognition, Visual; D011594:Psychometrics / Q000706:statistics & numerical data; D011930:Reaction Time; D015203:Reproducibility of Results; D013223:Statistics as Topic