Overview: Delirium is a clinical syndrome marked by an abrupt change in consciousness, attention, and cognition. It typically develops over hours to days and tends to fluctuate in severity throughout the day. Because it signals an underlying problem rather than being a single disease, clinicians consider it a medical symptom that warrants investigation and treatment. See further guidance at relevant medical sources.
Characteristics and common features
Core features include reduced ability to focus, sustain or shift attention, altered awareness of the environment, and disturbances in thinking, memory, perception or sleep–wake cycle. Subtypes are often described as:
- Hyperactive: agitation, restlessness, or hallucinations.
- Hypoactive: quietness, withdrawal, slowed movement—frequently overlooked.
- Mixed: fluctuating signs of both hyperactivity and hypoactivity.
Causes and risk factors
Delirium arises when the brain is affected by an acute medical or toxic process. Typical causes include infections, metabolic disturbances, organ failure, withdrawal from alcohol or sedatives, medications (especially those with anticholinergic or sedative effects), surgery, and severe pain. Older age, pre-existing cognitive impairment, sensory impairment, and multiple medications increase vulnerability.
Diagnosis and clinical approach
Diagnosis relies on clinical assessment: history, bedside cognitive testing, and corroboration from family or caregivers about abrupt change. Standardized tools are used in practice to screen for delirium. Because many precipitants are medical and potentially reversible, evaluation focuses on identifying infections, medication effects, metabolic abnormalities, and other treatable causes. For concise clinical summaries see clinical information resources.
Management, prognosis and prevention
Treatment centers on identifying and correcting underlying causes, ensuring hydration and nutrition, optimizing sleep and sensory input (glasses, hearing aids), and providing reorientation and a calm environment. Restraints and unnecessary psychoactive drugs are avoided when possible; short-term medication may be used for severe agitation. Delirium is associated with longer hospital stays and increased risk of complications and mortality; persistent cognitive decline can follow severe or prolonged episodes.
Distinguishing delirium from dementia
Unlike chronic dementia, delirium has an acute onset and fluctuating course with prominent attention deficits. Dementia develops gradually and produces stable, progressive cognitive decline. Nevertheless, dementia is a major risk factor for delirium and the two conditions can coexist, complicating diagnosis and care.