Objective: The primary aim of this study was to investigate the cognitive strategies used in semantic fluency (clustering, switching, and access to subcategories) in amnestic mild cognitive impairment (aMCI). In addition, we evaluated the impact of slowing in speed of information processing on semantic fluency performance.
Method: Tests of semantic verbal fluency (animals, supermarket items) were administered to 33 participants with aMCI and 33 healthy older adults (HOA). A selected measure of speed of information processing was also administered.
Results: Analyses revealed significant impairment in word generation (animals, supermarket items) in the aMCI group relative to the HOA group (η² = .41). Furthermore, the aMCI group produced significantly smaller cluster sizes (η² = .12) and accessed fewer subcategories than the HOA group (η² = .11), whereas a difference in switching frequency between groups produced a small but nonsignificant effect. Although the aMCI group, as compared with the HOA group, demonstrated reductions in processing speed (η² = .17), covariance analyses adjusting for speed did not substantively alter the significant difference between groups in clustering and access to subcategories.
Conclusions: When attempting semantic fluency, and as compared with healthy older adults, people with aMCI demonstrated difficulties in isolating semantic categories and loss of associative links within semantic categories. These findings are discussed in relation to an early degradation of semantic memory in aMCI.