Background: Little is known about relationships between Cognitive Impairment (CI) and verbal fluency measures in patients with a Clinically Isolated Syndrome (CIS) suggestive of Multiple Sclerosis. The aim of this study was to assess the extent of verbal fluency deficits and their predictive value for the presence of a CI in a population of CIS patients.
Methods: CI was detected by the Rao's Brief Repeatable Battery (BRB) and the Stroop Test (ST) in 100 CIS patients. The BRB includes the Word List Generation (WLG) test for semantic verbal fluency. The FAS test was used to investigate phonemic verbal fluency. CI was defined as the failure in at least 3 tests on BRB (without WLG to exclude criterion contamination bias) and ST.
Results: Eleven patients failed in at least 3 of the BRB tests and were classified as cognitively impaired. The comparison of Receiver Operating Characteristic curves showed that the Area Under the Curve (AUC) of the WLG was not significantly different from the AUC of the FAS (0.787 vs 0.755; p=N.S.). A cut-off <17 words for the WLG achieved 64% of sensitivity and a 79% of specificity, and a cut-off <28 words achieved 82% of sensitivity and a 66% of specificity in discriminating patients with CI.
Conclusions: Verbal fluency deficits occur early in the disease course and may predict the presence of CI in CIS patients.
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