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.Anosognosia (from the Greek “nosos” (illness) and “gnosis” (knowledge)) is a term coined by Babinski to refer to the phenomenon of denial of hemiplegia.¹ From an etymological perspective, the term anosognosia may be construed as the lack of knowledge or awareness of an illness. Anosognosia has also been reported among patients with Wernicke''s aphasia, who do not attempt to correct paraphasias and who may become irritable with others when their jargon‐loaded speech is not properly understood. Anton''s syndrome occurs in patients with cortical blindness, who deny being blind and confabulate responses when asked to recognise visually presented objects. In the context of people with Alzheimer''s disease, anosognosia was construed as the denial or lack of awareness of impairments in activities of daily living (ADL) or about neuropsychological deficits.^2,3 Different strategies have been used to assess anosognosia in Alzheimer''s disease, and these are briefly described as follows (see Clare^4,5 for a thorough review).