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14.3: Delirium

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    221823

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    Learning Objectives
    • Explain delirium and its etiology

    Delirium, also known as acute confusional state, is an organically caused decline from a previous baseline mental functioning that develops over a short period of time, typically hours to days. Delirium is a syndrome encompassing disturbances in attention, consciousness, and cognition. Delirium may also involve other neurological deficits, such as psychomotor disturbances (e.g., hyperactive, hypoactive, or mixed), impaired sleep-wake cycle, emotional disturbances, and perceptual disturbances (e.g., hallucinations and delusions), although these features are not required for diagnosis. A person who is experiencing delirium will be confused and disoriented and may not know who they are or where they are. 

    Old sketch from a 1910 textbook of a man with delirium who is attached to a bed in what looks like a jail cell.
    Figure \(\PageIndex{1}\): Delirium is an acute disturbance of mental abilities

    Delirium is caused by an acute organic process, which is a physically identifiable structural, functional, or chemical problem in the brain that may arise from a disease process outside the brain that nonetheless affects the brain. Delirium may result from an underlying disease process (e.g., infection or hypoxia), a side effect of a medication, withdrawal from drugs, over-consumption of alcohol, usage of hallucinogenic deliriants, or from any number of factors affecting one’s overall health (e.g., malnutrition, pain, etc.). In contrast, fluctuations in mental status/function due to changes in primarily psychiatric processes or diseases (e.g., schizophrenia or bipolar disorder) do not, by definition, meet the criteria for delirium.

    Delirium may be difficult to diagnose without the proper establishment of a person’s usual mental function. Without careful assessment and history, delirium can easily be confused with a number of psychiatric disorders or chronic organic brain syndromes because of many overlapping signs and symptoms in common with dementia, depression, psychosis, etc. Delirium may manifest from a baseline of existing mental illness, baseline intellectual disability, or dementia, without being due to any of these problems. Delirium is distinguished from dementia (chronic organic brain syndrome), which describes an acquired (non-congenital) and usually irreversible cognitive and psychosocial decline in function.

    The difference between delirium and similar psychiatric illness

    Delirium is a disorder that makes situational awareness and processing new information very difficult for those diagnosed. Delirium usually has a high rate of onset ranging from minutes to hours and sometimes days, but it does not last for very long, only a few hours to weeks. Delirium can also be accompanied by a shift in attention, mood swings, violent or unordinary behaviors, and hallucinations. Delirium may be caused by a preexisting medical condition. Delirium is noted by sudden changes in cognition. Alzheimer’s disease, depression, and some psychotic disorders tend to be more of a gradual cognition decline.

     
    Table 1. Characteristics of delirium, Alzheimer’s disease, depression, and psychotic disorders
    Attributes Delirium Alzheimer’s disease Depression Psychotic Disorders
    Onset Sudden/acute/subacute Gradual Gradual Acute or gradual
    Progression Shifts in severity, likely to resolve in days to weeks. Worsens over a period of time Acute or chronic with acute exacerbation Chronic with acute exacerbation
    Hallucinations May be present, mostly visual Mostly absent (exceptions: Lewi body dementia, etc.) May be present if associated with psychotic features Present
    Delusions Fleeting Mostly not present May be present Present
    Psychomotor activity Increased or decreased, may shift from increased to decreased states. May or may not change Change Change
    Attention Poor attention span and impaired short term memory. Progressive worsening short-term memory. Attention span is likely to be affected in severe cases May be altered May be altered
    Consciousness Altered, rapidly shifts Mostly intact until severe stages Normal Normal
    Attention Altered, rapidly shifts Mostly intact until severe stages May be altered May be altered
    Orientation Altered, rapidly shifts Mostly intact until severe stages Not altered Not altered
    Speech Not coherent Errors Slow Normal or pressured
    Thought Disorganized Impoverished Normal Disorganized
    Perceptions Altered, rapidly shifts Mostly intact until severe stages Normal May be altered
    EEG Moderate to severe background slowing Normal or mild diffuse slowing Normal Normal
    Reversibility Mostly Very rarely Yes Rarely

    Treatment of delirium requires identifying and managing the underlying causes, managing delirium symptoms, and reducing the risk of complications. In some cases, temporary or symptomatic treatments are used to comfort the person or to facilitate other care (e.g., preventing people from pulling out a breathing tube). Antipsychotics are not supported for the treatment or prevention of delirium among those who are in hospital. When delirium is caused by alcohol or sedative-hypnotic withdrawal, benzodiazepines are typically used. Evidence has found that the risk of delirium in hospitalized people can be reduced by systematic good general care. Delirium affects 14–24% of all hospitalized individuals. The overall prevalence for the general population is 1%-2% but this prevalence increases with age, reaching 14% of adults over age 85. Among older adults, delirium occurs in 15–53% of those post-surgery, 70–87% of those in the ICU, up to 60% of those in nursing homes or post-acute care settings. Among individuals requiring critical care, delirium is a risk for death within the next year.

    Watch It

    This video provides an overview of the causes, symptoms, diagnosis, and treatment of delirium.

    You can view the transcript for “Delirium – causes, symptoms, diagnosis, treatment & pathology” here (opens in new window).

    Key Takeaways: Delirium
    Query \(\PageIndex{1}\)
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    Glossary

    delirium: an organically caused decline from a previous baseline mental functioning that develops over a short period of time, typically hours to days

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