Cats and Apples: Semantic Fluency Performance for Living Things Identifies Patients with Very Early Alzheimer's Disease

Objective: Reduced semantic memory performance is a known neuropsychological marker of very early Alzheimer’s disease (AD), but the task format that best predicts disease status is an open question. The present study aimed to identify the semantic fluency task and measure that best discriminates early-stage AD patients (PATs) from cognitively healthy controls. Method: Semantic fluency performance for animals, fruits, tools, and vehicles was assessed in 70 early-stage AD PATs and 67 cognitively healthy participants. Logistic regressions and receiver operating characteristics were calculated for five total score semantic fluency measures. Results: Compared with all other measures, living things (i.e., total correct animals + total correct fruits) achieved highest z-statistics, highest area under the curve and smallest difference between the upper and lower 95% confidence intervals. Conclusion: Living things total correct is a powerful tool to detect the earliest signs of incipient AD.