Awareness of cognitive deficits and anosognosia in probable Alzheimer's disease.

We examined the relationship between unawareness of cognitive deficits and psychiatric and neuropsychological manifestations in 181 patients with probable Alzheimer's disease (AD). Patients unaware of their cognitive deficits were more cognitively impaired, as measured by the Mini-Mental State Examination, and had a specific defect in 'frontal/executive' functions. The presence of major depression, delusions and hallucinations was no more likely among patients who were aware of their cognitive impairment than among those who were not. These findings have important implications for the understanding of anosognosia and deficit awareness in dementia.