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

The diagnostic accuracy of the AD8 informant questionnaire for cognitive impairment was assessed in patients referred to a dedicated memory clinic. This pragmatic prospective study of consecutive referrals attending with an informant who completed AD8 (n 212) lasted 12 months. Diagnosis used standard clinical diagnostic criteria for dementia and mild cognitive impairment as reference standard (prevalence of cognitive impairment 0.62). The AD8 proved acceptable to informants, was quick, and easy to use. Using the cutoff of 2/8, AD8 was highly sensitive (0.97) for diagnosis of cognitive impairment but specificity was poor (0.17). Combining AD8 with either the Mini-Mental State Examination or the Six-Item Cognitive Impairment Test showed little additional diagnostic benefit. In conclusion, AD8 is very sensitive for cognitive impairment in a memory clinic but specificity may be inadequate