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Delirium, or acute confusional state, is an organically-caused decline from a previously attained baseline level of cognitive function. It is typified by fluctuating course, attentional deficits and generalized severe disorganization of behavior. It typically involves other cognitive deficits, changes in arousal (hyperactive, hypoactive, or mixed), perceptual deficits, altered sleep-wake cycle, and psychotic features such as hallucinations and delusions. Delirium itself is not a disease, but rather a clinical syndrome (a set of symptoms). It may result from an underlying disease, from drugs administered during treatment of that disease in a critical phase, withdrawal from drugs, from a new problem with mentation, or from varying combinations of two or more of these factors. It is a corollary of the criteria that a diagnosis of delirium usually ''cannot'' be made without a previous assessment, or knowledge, of the affected person's ''baseline'' level of cognitive function. In other words, a mentally disabled or demented person who is operating at their own baseline level of mental ability would be expected to appear delirious without a baseline mental functional status against which to compare. Delirium may be caused by a disease process outside the brain that nonetheless affects the brain, such as infection (urinary tract infection, pneumonia) or drug effects, particularly anticholinergics or other CNS depressants (benzodiazepines and opioids). Although hallucinations and delusions are sometimes present in delirium, these are not required for the diagnosis, and the symptoms of delirium are clinically distinct from those induced by psychosis or hallucinogens (with the exception of deliriants.) Delirium must by definition be caused by an organic process, i.e., a physically identifiable structural, functional, or chemical problem in the brain (see organic brain syndrome), and thus, fluctuations of mentation due to changes in purely psychiatric processes or diseases, such as sudden psychosis from schizophrenia or bipolar disorder, are (by definition) not termed delirium. Like its components (inability to focus attention, mental confusion and various impairments in awareness and temporal and spatial orientation), delirium is the common manifestation of new organic brain dysfunction (for any reason). Delirium requires both a sudden change in mentation, and an organic cause for this. Thus, without careful assessment and history, delirium can easily be confused with a number of psychiatric disorders or long term organic brain syndromes, because many of the signs and symptoms of delirium are conditions also present in dementia, depression, and psychosis. Delirium may newly appear on a background of mental illness, baseline intellectual disability, or dementia, without being due to any of these problems. Treatment of delirium requires treating the underlying cause. In some cases, temporary or palliative or symptomatic treatments are used to comfort patients or to allow better patient management (for example, a patient who, without understanding, is trying to pull out a ventilation tube that is required for survival). Delirium is probably the single most common acute disorder affecting adults in general hospitals. It affects 10-20% of all hospitalized adults, and 30-40% of elderly hospitalized patients and up to 80% of ICU patients. In ICU patients or in other patients requiring critical care, delirium is not simply an acute brain disorder but in fact is a harbinger of much greater likelihood of death within the 12 months which follow the ICU patient's hospital discharge. ==Definition== In common usage, delirium is often used to refer to drowsiness, disorientation, and hallucination. In medical terminology, however, a number of different symptoms, including temporary disturbance in consciousness, with reduced ability to focus attention and solve problems, are the core features of delirium. Occasionally sleeplessness and severe agitation and irritability are part of "delirium." Hallucination, drowsiness, and disorientation are not required, but may be contribute to the diagnosis. There are several medical definitions of delirium (including those in the DSM-IV and ICD-10). However, all include some core features. The core features are: * Disturbance of consciousness (that is, reduced clarity of awareness of the environment, with reduced ability to focus, sustain, or shift attention)〔Hales E and Yudofsky JA, eds, The American Psychiatric Press Textbook of Psychiatry, Washington, DC: American Psychiatric Publishing, Inc., 2003〕 * Change in cognition (e.g., problem-solving impairment or memory impairment) or a perceptual disturbance (hallucination)〔 * Onset of hours to days, and tendency to fluctuate.〔 * Behaviour may be either overactive or underactive, and sleep is often disturbed, with loss of the normal Circadian rhythm.〔 * Thinking is slow and muddled but the content is often complex.〔Gelder, Mayou, Geddes (2005). Psychiatry. (Pg.138) New York, NY: Oxford University Press Inc.〕 Other clinical features include disorganized thinking, poor memory, delusions, and mood lability.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「delirium」の詳細全文を読む スポンサード リンク
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