Category Archives: Delirium


Delirium is a complex neuropsychiatric disorder that occurs commonly among patients in all health care settings, especially among the elderly and those with preexisting brain lesions or cognitive impairment. It is primarily characterized by generalized impairment of cognition, especially orientation and attention, but also involves a range of noncognitive symptoms, including motor behavior, sleep-wake cycle,… Read More »

Delirium: Epidemiology

Delirium can occur at any age, although it is particularly understudied in children and adolescents. Most epidemiological studies have focused on the elderly, who are at higher risk to develop delirium than are younger adults. This is likely because of age-related changes in the brain, including decreased cholinergic functioning, often referred to as reduced brain… Read More »

Delirium: Risk Factors

Delirium is particularly common during hospitalization when a confluence of both predisposing (vulnerabilities) and precipitating factors is present. Several patient, illness, pharmacological, and environmental factors have been identified as being relevant risk factors for delirium. Although some factors are more relevant in certain settings, age, preexisting cognitive impairment, severe co-morbid illness, and medication exposure are… Read More »

Delirium: Mortality

Delirium appears to be associated with high mortality. Whether this mortality risk is increased during the index admission, at long-term follow-up, or both is not completely clear; this uncertainty is in part related to challenges in research design. It is also not known whether increased mortality is attributable to the underlying etiologies of delirium; to… Read More »

Reversibility of a Delirium Episode

Delirium traditionally has been distinguished from dementia by its potential for reversal. In most cases, delirium is reversible, except in terminal illness or particular examples of severe brain injury. However, evidence that an index episode of delirium may be associated with enduring cognitive deficits suggests that delirium may be more than a transient state. Longer… Read More »

Delirium: Phenomenology

The classic descriptive study of 106 “dysergastic reaction” (i.e., delirium) patients by Wolff and Curran (1935) is still consistent with current conceptions of delirium phenomenology. Inconsistent and unclear definitions of symptoms and underuse of standardized symptom assessment tools have hampered subsequent efforts to describe delirium phenomenology or to compare symptom incidences across studies and etiological… Read More »

Delirium: Motor Subtypes

There has been much interest in whether there are subtypes of delirium, derived from various parameters such as underlying physiology, etiology, and symptom profile, similar to the way heart failure is categorized. It is unclear whether such meaningful subtypes exist. Nonetheless, the most studied possible subtype is based on psychomotor behavior. Although not all patients… Read More »

Delirium: Diagnosis

Specific diagnostic criteria for delirium first appeared in DSM-III, around the same time as the first symptom rating scales for delirium. Thus, early clinical reports and research based on the first two editions of DSM (American Psychiatric Association 1952, 1968) or Research Diagnostic Criteria (RDC) were affected by this lack of diagnostic specificity. DSM-I was… Read More »

Delirium: Cognitive Assessment

Because delirium is primarily a cognitive disorder, bedside assessment of cognition is critical to proper diagnosis. Although all cognitive domains — orientation, attention, short-and long-term memory, visuoconstructional ability, and executive function — are affected in delirium, attention deficits are the most specifically emphasized in DSM. Pattern and timing of deficits assist in differential diagnosis from… Read More »

Delirium Assessment Instruments

Diagnostic criteria are important in diagnosing delirium, and cognitive tests are useful in documenting cognitive impairment. Rating a range of delirium symptoms, however, requires other methods. More than 10 instruments have been proposed to assess symptoms of delirium for screening, diagnosis, or symptom severity rating. Nonvalidated measures, designed for use in a single study, continue… Read More »