amnestic disorder
in DSM–IV–TR, a disturbance in memory marked by inability to learn new information (anterograde amnesia) or to recall previously learned information or past events (retrograde amnesia) that is severe enough to interfere markedly with social or occupational functioning or represents a significant decline from a previous level of functioning. A distinction is made between amnestic disorder due to a general medical condition, substance-induced persisting amnestic disorder, and amnestic disorder not otherwise specified. The first of these can be caused by a variety of conditions, such as head injury, anoxia, herpes-simplex encephalitis, and posterior cerebral artery stroke, resulting in lesions in specific brain regions, including the medial temporal lobe and the diencephalon, and their connections with various cortical areas. It may be transient, lasting from several hours to no more than a
month (see also transient global amnesia), or chronic (lasting more than 1 month). In DSM–5, amnestic disorder, along with dementia, has been subsumed into the category major neurocognitive disorder and is no longer considered a distinct entity. Formally called amnesic (or amnestic) syndrome.