Unawareness of the disease or anosognosia is a common symptom among many neuropsychiatric patients and may affect the quality of life and treatment compliance in patients suffering from AD and make them to behave unsafely. Although generalized cognitive impairment may be a prerequisite for anosognosia in dementia, not all patients with cognitive impairment, present anosognosia. Deficit in regional cerebral blood flow (rCBF) can be seen in different brain regions in dementia with a typical posterior temporoparietal defect in patients with Alzheimer's disease. Although functional brain imaging methods such as single photon emission computed tomography (SPECT) have relatively limited spatial resolution, they offer the potential advantage of being able to assess functional connectivity patterns, associated with neural networks involved in awareness. We try to determine the brain regions that contributed to unawareness in patients with Alzheimer's disease, using SPECT. This study will focus on awareness deficits in cognitive and behavioral domains, rather than personality.