AD8

Functionality & Mechanism

The AD8 application, developed by Washington University, implements the Ascertain Dementia 8-item Informant Questionnaire. The interface facilitates administration to an informant or, if unavailable, directly to the patient. The eight questions, which assess for intra-individual decline in memory, orientation, judgment, and function, can be self-administered or read aloud in person or by phone. The system provides integrated guidelines for administration and interpretation of results, with sessions typically completed in under three minutes.

Evidence & Research Context

• A validation study in a clinical sample (N=255 patient-informant dyads) established strong concurrent validity with the Clinical Dementia Rating (CDR) (r=0.75), excellent internal consistency (Cronbach's alpha = 0.84), and high discriminative ability (AUC = 0.92).
• The instrument's initial development demonstrated that a cut-off score of two endorsed items differentiates individuals with very mild dementia from those without, achieving 74% sensitivity and 86% specificity.
• A subsequent psychometric analysis (N=403) using data from the National Health and Aging Trends Study confirmed a unidimensional measurement structure, robust reliability (Cronbach's alpha = 0.89), and no differential item functioning.
• The instrument demonstrates robust reliability for both in-person and telephone administration (weighted kappa = 0.65-0.67) and very good interrater reliability (ICC = 0.80).

Intended Use & Scope

This application is designed for clinicians and researchers as a preliminary screening tool to detect early cognitive changes indicative of dementia. It facilitates the identification of individuals who require further diagnostic assessment. The AD8 is not a standalone diagnostic instrument; scores indicating impairment necessitate a comprehensive evaluation by a qualified medical provider.