Digit Span and Verbal Fluency Tests in Patients with Mild Cognitive Impairment and Normal Subjects in Thai-Community†
Weerasak Muangpaisan MD, MPhil*, Somboon Intalapaporn MD*, Prasert Assantachai MD, FRCP*
Affiliation : † The abstract of this study was presented as a poster at the American Geriatrics Society 2007 Annual Scientific Meeting and was published in J Am Geriatr Soc 2007; 55 (4 Suppl): S105 * Department of Preventive and Social Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
Background : Far too little attention has been paid to the difference of Digit Span test and category verbal
fluency test (CVFT) between normal and mild cognitive impairment (MCI) subjects.
Objective : To investigate the difference of Digit Span test and CVFT between normal subjects and patients
with MCI and study the influence of age, gender, and education on the task performance.
Material and Method: The authors collected data of 77 participants diagnosed with amnestic MCI (from 517
participants screened) and 30 normal subjects aged 50 or over enrolled from communities in Bangkok. The
Digit Span test and CVFT (semantic fluency and Controlled word association test for letter fluency) were used
to evaluate the subjects.
Results : MCI patients had significantly lower digit span score, in both Digits Forward and Digits Backward,
poorer performance on semantic fluency for animals and fruits and letter fluency test. The logistic regression
model of MCI diagnosis showed that only Digits Backward score was a predictor of MCI diagnosis (OR 0.643
for each increment of 1 digit, p = 0.009, 95% confidence interval 0.462-0.896). The cut-off point of Digit
Backward score was 4 and yielded sensitivity of 77% and specificity of 57%. Females had lower scores than
males in every test except semantic fluency for fruits. The digit span and semantic fluency scores decreased as
age increased but letter fluency increased correspondently with age. The digit span and CVFT scores
increased in parallel with the increase of education.
Conclusion : MCI patients had poorer performance on the Digit Span and CVFT tests than normal age and
education matched subjects. Digits Backward test can predict the MCI diagnosis. Age, gender and education
have an impact on the performance of the tests.
Keywords : Mild cognitive impairment, Verbal fluency, Digit span, Community, Elderly
