Comprehensive Evaluation of the Functional Activities Questionnaire (FAQ) and Its Reliability and Validity

Area of Science:

• Gerontology
• Neuroscience
• Psychometrics

Background:

• The Functional Activities Questionnaire (FAQ) is widely used to assess daily living difficulties.
• Previous psychometric analyses of the FAQ were limited in scope and methodology.

Purpose of the Study:

• To consolidate and expand psychometric analyses of the FAQ using generalizability and item response theories.
• To evaluate the reliability and validity of the FAQ in a large, diverse sample.

Main Methods:

• Utilized data from 27,916 individuals in the National Alzheimer's Coordinating Center database.
• Employed internal consistency, test-retest, generalizability, confirmatory factor, and item response theory analyses.
• Assessed validity through convergence with neurocognitive measures and classification accuracy with impairment stage.

Main Results:

• Demonstrated strong reliability (0.52-0.95) and validity, with significant correlations to neurocognitive measures (r = -.30 to -.59).
• Achieved strong classification accuracy (AUC = .81-.99) for impairment stages.
• Confirmed a robust single-factor model and strong item discrimination, particularly for mild functional difficulties.

Conclusions:

• The FAQ is a reliable and valid tool for assessing activities of daily living in clinical and research settings.
• The FAQ is particularly effective in identifying mild functional impairments, aiding in the differentiation of normal cognition, mild cognitive impairment, and dementia.