Usefulness of Verbal Fluency Performance as Follow-up Screening Tool in Patients With Mild to Moderate Alzheimer's Disease

ABSTRACT

BACKGROUND: Impaired verbal fluency in Alzheimer's disease (AD) has been well documented. Furthermore, crosssectional studies suggest that semantic fluency is disproportionately impaired relative to phonemic fluency in AD. The aim of this study was to determine the ability of fluency measures as follow-up screening tool for mild to moderate AD. METHODS: Participants were recruited from AD patients in mild to moderate stages. We annually evaluated semantic (animal, supermarket) and phonemic (giyeok, siot, ieung) fluency and tested other extensive neuropsychological measures for two years. RESULTS: A total of 33 AD patients were included at baseline and 1-year follow-up, who were aged 70.18+/-5.97 years at baseline. Eleven patients completed a 2-year follow-up. Phonemic fluency total score was not significantly changed during the study period. However, semantic fluency total score tended to decline annually, and significantly declined at 2-year follow-up compared to baseline. In addition, difference score (semantic fluency minus phonemic fluency) was significantly decreased at every follow-up compared to previous year. In Pearson correlation analyses between changes of verbal fluency and other neuropsychological measures, changes of semantic fluency appeared to be significantly correlated with neuropsychological measures much more than changes of phonemic fluency. CONCLUSIONS: Significant longitudinal declines in semantic fluency compared to phonemic fluency seem to be consistent with previous cross-sectional studies. These patterns of changes in verbal fluency were observed even at an interval of one year follow-up in our study. The verbal fluency might be useful follow-up screening test for mild to moderate AD in the memory clinic setting.