Disorders of awareness in neuropsychiatric syndromes: an update.

Impaired awareness has been reported in a number of neuropsychiatric disorders. The purpose of this review is to provide an update on the current understanding of impaired awareness in neuropsychiatric syndromes, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), traumatic brain injury (TBI), schizophrenia, mood disorders, and obsessive-compulsive disorder (OCD). Unawareness of illness or deficits can have important diagnostic, treatment, and functional implications, and further understanding of its clinical and neural correlates will be extremely helpful in mediating its impact. Nevertheless, the area of unawareness has received relatively little attention as compared with other manifestations of neuropsychiatric illness. Evidence supporting a role for the involvement of frontal and parietal lobes across disorders is presented. Although most research has used neuropsychologic measures to assess brain functioning, more recent, limited literature in AD and schizophrenia has begun to examine neural correlates of unawareness using structural and functional imaging.