Two dimensions of anosognosia in patients with Alzheimer's disease: reliability and validity of the Japanese version of the Anosognosia Questionnaire for Dementia (AQ-D).

Although a number of studies have examined anosognosia of cognitive deficits in patients with Alzheimer's disease (AD), not much is known about the anosognosia of behavioral symptoms in AD. The aims of the present study were to establish a Japanese version of the Anosognosia Questionnaire-Dementia (AQ-D) and to examine its factor structure, reliability and validity, and to identify the effects of various variables on the AQ-D. Factor structure, internal consistency, test-retest reliability and concurrent validity of the Japanese version of the AQ-D were analyzed. Multiple regression was then done using the results of the AQ-D as dependent variables and entering all relevant predictor variables. Both the internal consistency and the test-retest reliability of the AQ-D were excellent. Factor analysis indicated four factors: anosognosia of basic and instrumental activities of daily living; that of episodic memory and orientation; that of disinhibited behaviors; and that of apathy and depression. The first two factors were regarded as anosognosia of cognitive deficits and were associated with Mini-Mental State Examination scores, while the latter two factors were regarded as anosognosia of behavioral symptoms and were associated with the Neuropsychiatric Inventory (NPI) score. A dissociation between the two domains of anosognosia was confirmed, namely of cognitive deficits and of behavioral symptoms using the Japanese version of the AQ-D. The knowledge that various factors may have different effects on different domains of anosognosia in patients with AD may serve as useful information for clinicians assessing anosognosia in AD.