Meta‐Analysis of Animal Fluency Performance in Amnestic Mild Cognitive Impairment and Cognitively Unimpaired Older Adults.

Abstract

AbstractBackgroundAnimal fluency is a commonly used neuropsychological measure that is used in the diagnosis of mild cognitive impairment (MCI) and Alzheimer’s disease (AD). Although most individuals with MCI have clinically normal scores on this test, several studies have shown the MCI individuals’ performance is significantly lower than that of cognitively unimpaired (CU) individuals. The aim of this meta‐analysis will be to characterize the effect size of animal fluency performance differences between MCI and CU individuals.MethodLiterature search with search terms used were: “animal fluency and mild cognitive impairment”, “semantic fluency and mild cognitive impairment”, “category fluency and mild cognitive impairment”. Data was extracted only from studies that met the following criteria: 1. It was to be an observational study (interventional studies were excluded; 2. Peterson criteria was used for diagnosis of the MCI individuals; 3. The study had raw data available animal fluency performance. Both the standardized mean difference (SMD) and the raw mean difference (RMD) were derived from random effects analyses. Demographically adjusted z‐scores for Animal fluency performance for the MCI groups were obtained to determine normative performance.ResultTwenty studies were included in the analysis. The SMD for animal fluency performance between CU and MCI was 0.89 (95% confidence interval: [0.73; 1.04], p<0.001), I^2 = 68.6% [50.2%; 80.2%], which reflects a large effect size with moderate heterogeneity. The RMD was ‐4.09 [‐4.78; ‐3.40], p<0.001 indicating that MCI individuals generated significantly fewer animals than CU individuals. The mean z‐score for MCI groups’ animal fluency scores was z = ‐0.75 indicating performance in the Low Average range.ConclusionThis study found a large effect size for differences on animal fluency performance between MCI and CU individuals. On average, the MCI groups’ normative performance did not fall into the Impaired range indicating that there are important sub‐clinical differences on animal fluency performance between CU and MCI individuals. These findings are relevant to the use of composite efficacy measures for AD prevention trials. Specifically, the inclusion of animal fluency in these composite scores may help increase their sensitivity to change and yield greater statistical power for these trials.