Anosognosia in mild cognitive impairment and mild Alzheimer's disease: frequency and neuropsychological correlates.

OBJECTIVES: To evaluate severity of anosognosia and to identify its neuropsychological correlates in preclinical and clinical Alzheimer's Disease (AD).
METHODS: The Clinical Insight Rating Scale, the Anosognosia Questionnaire for Dementia (AQ-D), and the Mental Deterioration Battery were used to assess anosognosia and cognitive performances in mild AD (N = 38), amnesic mild cognitive impairment (a-MCI; N = 35), and multiple domain MCI (md-MCI; N = 38).
RESULTS: Patients with mild AD were more anosognosic than both MCI groups, which, however, did not differ from one other. A categorical diagnosis of anosognosia was made in 42% of patients with mild AD, 3% of md-MCI, but in no subjects with a-MCI. Reduced verbal episodic memory raw score was associated with decreased awareness of cognitive difficulties (AQ-D total and intellectual functioning scores) only in MCI. In mild AD, anosognosia was linked only to increased age and reduced basic activities of daily living performances.
CONCLUSIONS: The diagnosis of anosognosia is frequent in patients with mild AD but not in those with MCI. In the latter case, the authors cannot speak of true anosognosia but only of decreased awareness of illness. Furthermore, reduced awareness of cognitive difficulties is linked with verbal memory performances in patients with MCI but not in those with AD, suggesting for the latter the involvement of factors other than neuropsychological. Thus, neuropsychiatric dimensions commonly present in patients with AD should be investigated along with anosognosia.