An examination of the clinical utility of phonemic fluency in healthy adults and adults with mild cognitive impairment

The Controlled Oral Word Association Test (COWAT) is a widely utilized measure of phonemic fluency. However, two issues remain: (1) whether demographic, cognitive variables, or version of test administered predict performance; (2) if the test is predictive of Mild Cognitive Impairment (MCI). Recent studies report that item-level analyses such as lexical frequency may be more sensitive to early cognitive change. The purpose of this study was to examine the clinical utility of the COWAT, considering both total correct words and the lexical frequency. Sixty-seven healthy adults and thirty-seven adults with MCI completed neuropsychological testing. Mann–Whitney U tests were used to determine if there was a difference in COWAT performance between groups. Elastic net regression models were used to assess whether variance in total scores/lexical frequencies can be predicted by demographics, test version, or diagnosis; which cognitive tests explained the variance in performance; and how total scores and lexical frequencies compared with other cognitive tests in predicting diagnosis. Overall, individuals with MCI produced fewer and higher frequency words. The variance in total correct words or lexical frequency was not explained by demographics, test version, or diagnosis. Total correct words was a more important predictor of diagnosis than lexical frequency.