A diagnostic formulation for anosognosia in Alzheimer's disease

Objective: To determine the earliest symptoms of anosognosia in people with Alzheimer's disease and to validate a criteria-guided strategy to diagnose anosognosia in dementia. Methods: A consecutive series of 750 patients with very mild or probable Alzheimer's disease attending a memory clinic, as well as their respective care givers, was assessed using a comprehensive psychiatric evaluation. Results: The factors of anosognosia for (1) basic activities of daily living (bADL), (2) instrumental activities of daily living (iADL), (3) depression and (4) disinhibition were produced by a principal component analysis on the differential scores (ie, caregiver score minus patient score) on the anosognosia questionnaire for dementia. A discrepancy of two or more points in the anosognosia-iADL factor was found to have a high sensitivity and specificity to identify clinically diagnosed anosognosia in people with Alzheimer's disease. By logistic regression analysis, the severity of dementia and apathy were both shown to be noticeably associated with anosognosia in people with Alzheimer's disease. Conclusion: Anosognosia in those with Alzheimer's disease is manifested as poor awareness of deficits in iADL and bADL, depressive changes and behavioural disinhibition. The frequency of anosognosia is found to increase considerably with the severity of dementia. The validity of a specific set of criteria to diagnose anosognosia in people with Alzheimer's disease was shown, which may contribute to the early identification of this condition.