Development of a screening algorithm for Alzheimer's disease using categorical verbal fluency

Area of Science:

• Neurology
• Gerontology
• Cognitive Science

Background:

• Early and accurate screening for Alzheimer's disease (AD) is crucial for timely intervention and management.
• Existing screening tools like the Mini-Mental State Examination (MMSE) have limitations in terms of brevity and accessibility.
• The categorical verbal fluency test (CVFT) shows potential for AD screening but requires optimization for enhanced diagnostic accuracy.

Purpose of the Study:

• To develop and validate a weighted composite score for the CVFT to improve its accuracy in screening for mild probable Alzheimer's disease (AD).
• To compare the diagnostic performance of the novel CVFT composite score against the traditional CVFT total score and the MMSE.
• To assess the feasibility of the CVFT composite score as a brief, cost-effective, and widely applicable screening tool for AD.

Main Methods:

• A weighted composite score was derived from CVFT subindex scores using a logistic regression model in 423 participants (mild probable AD patients and cognitively normal controls).
• The logistic regression model incorporated variables such as gender, age, education level, first-half score, switching score, clustering score, and perseveration score.
• Diagnostic accuracy was evaluated using the area under the receiver operating characteristic curve (AUC), sensitivity, and specificity, with comparisons made to the standard CVFT total score and the MMSE.

Main Results:

• The weighted CVFT composite score demonstrated a high AUC of 0.903 for AD detection, significantly outperforming the standard CVFT total score (p<0.001).
• Bootstrapped re-sampling confirmed the superior diagnostic accuracy, sensitivity, and specificity of the composite score compared to the total CVFT score across multiple iterations.
• While the AUC for the CVFT composite score (0.903) was slightly lower than that of the MMSE (0.930, p=0.006), its practical advantages in brevity, cost, and ease of administration (including phone/internet) are notable.

Conclusions:

• The developed weighted composite score significantly enhances the diagnostic accuracy of the CVFT for screening Alzheimer's disease.
• The CVFT composite score presents a valuable and practical alternative to the MMSE for widespread AD screening due to its ease of use and accessibility.
• Further validation and implementation of this optimized CVFT screening tool could facilitate earlier identification of individuals with Alzheimer's disease.