AD8 Informant Questionnaire for Cognitive Impairment: Pragmatic Diagnostic Test Accuracy Study

Area of Science:

• Neurology
• Geriatrics
• Psychometrics

Background:

• Cognitive impairment diagnosis is crucial for timely intervention.
• Informant-based questionnaires offer a valuable perspective in memory assessments.
• The AD8 (8-item informant questionnaire) is a screening tool for cognitive impairment.

Purpose of the Study:

• To evaluate the diagnostic accuracy of the AD8 informant questionnaire.
• To assess the AD8's sensitivity and specificity in a memory clinic setting.
• To determine if combining AD8 with other cognitive tests improves diagnostic utility.

Main Methods:

• A prospective, pragmatic study of 212 consecutive memory clinic referrals with informant AD8 completion.
• Cognitive impairment diagnosis used standard clinical criteria as the reference standard.
• Analysis focused on AD8's sensitivity and specificity at a cutoff of ≥2/8.

Main Results:

• The AD8 was found to be highly sensitive (0.97) for identifying cognitive impairment.
• However, the AD8 demonstrated poor specificity (0.17) for cognitive impairment.
• Combining AD8 with the Mini-Mental State Examination or Six-Item Cognitive Impairment Test offered minimal additional diagnostic benefit.

Conclusions:

• The AD8 is a sensitive tool for screening cognitive impairment in memory clinics.
• Its low specificity suggests it may not be sufficient as a standalone diagnostic instrument.
• Further research may explore optimizing AD8 use or combining it with other diagnostic methods.