title: Cut the coda: early fluency intervals predict diagnoses.
abstract: The aim of this study was threefold: (i) to clarify whether letter and category fluency tap different cognitive abilities; (ii) to make diagnostic comparisons and predictions using temporally resolved fluency data; (iii) to challenge and test the widely made assumption that 1-min sum scores are the fluency test measure of choice in the diagnosis of dementia. Scores from six 10-sec intervals of letter and category fluency tests were obtained from 240 participants including cognitive levels ranging from mild subjective cognitive complaints to Alzheimer's disease. Factor analysis revealed clearly separate factors corresponding to letter and category fluency. Category fluency was markedly impaired in Alzheimer's disease but not in Mild Cognitive Impairment. Only scores from relatively early intervals predicted Alzheimer's disease and Mild Cognitive Impairment. The conclusions are (i) letter and category fluency are different tests, category fluency being the best diagnostic predictor; (ii) it would be possible to administer category fluency tests only for 30 sec, because after this point the necessary differential diagnostic information about the patient's word fluency capacity has already been gathered.
authors.affiliation: Section for Clinical Geriatrics, Department of Neurobiology, Caring Sciences and Society, Karolinska Institutet, Stockholm, Sweden. sven-erik.fernaeus@swipnet.se
authors.forename: Sven-Erik
authors.initials: SE
authors.lastname: Fernaeus
authors.forename: Per
authors.initials: P
authors.lastname: Ostberg
authors.forename: Ake
authors.initials: A
authors.lastname: Hellström
authors.forename: Lars-Olof
authors.initials: LO
authors.lastname: Wahlund
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000145:classification / Q000523:psychology*; D003071:Cognition / Q000502:physiology; D003072:Cognition Disorders / Q000145:classification / Q000523:psychology*; D003627:Data Interpretation, Statistical; D004493:Education; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests; D011578:Psycholinguistics; D011597:Psychomotor Performance / Q000502:physiology; D014705:Verbal Behavior / Q000502:physiology*