DSM-5 Category: Neurocognitive Disorders


A person with delirium will present in a confused and disoriented state that fluctuates in its degree of severity. This disoriented state is caused by conscious, perceptual and cognitive disturbances and attention deficits. Under DSM-5, delirium is described as a disturbance of attention awareness and a change in baseline cognition. It is distinguished from similar inattention and cognitive impairments in other disorders by its degree of intensity. Symptoms widely associated with delirium are illusions and hallucinations. The person may not respond to normal verbal or physical stimuli during interaction with other persons and may be easily distracted. He/she may fail to demonstrate comprehension in these interactions. The onset of delirium is quick, typically a matter of hours or days. An episode of delirium will also be accompanied by sleep disturbances such as daytime sleep and nighttime wakefulness. In extreme cases, physical restraints may be used on a person with delirium engaging in behavior harmful to himself/herself or others.

Symptoms of Delirium

Major symptoms of delirium such as inattention and cognitive impairments also occur in many other mental disorders such as autism spectrum disorder, attention deficit hyperactivity disorder, and schizophrenia. In delirium, severe inattention and cognitive deficits are manifested. Delirium is most commonly experienced by the elderly and those with cognitive impairments (dementia). Substance abusers experience delirium both during use and withdrawal.

DSM-V sets out the following criteria for a diagnosis of delirium (APA, 2013):

  • A disturbance in attention (i.e., reduced ability to direct, focus, sustain, and shift attention) and awareness (reduced orientation to the environment).
  • The disturbance develops over a short period of time (usually hours to a few days), represents a change from baseline attention and awareness, and tends to fluctuate in severity during the course of a day.
  • An additional disturbance in cognition (e.g., memory deficit, disorientation, language, visuospatial ability, or perception).
  • The disturbances in Criteria A and C are not better explained by another preexisting, established, or evolving neurocognitive disorder and do not occur in the context of a severely reduced level of arousal, such as coma.
  • There is evidence from the history, physical examination, or laboratory findings that the disturbance is a direct physiological consequence of another medical condition, substance intoxication or withdrawal (i.e., due to a drug of abuse or to a medication), or exposure to a toxin, or is due to multiple etiologies.

Delirium is manifested in a number of disorders. DSM-5 provides guidance on how to differentiate the diagnosis of delirium disorder.

  1. Substance intoxication delirium is diagnosed when the symptoms in Criteria A and C predominate and are sufficiently severe to warrant clinical attention.
  2. Substance withdrawal delirium is diagnosed when symptoms in Criteria A and C predominate and are sufficiently severe to warrant clinical attention.
  3. Medication-induced delirium is diagnosed when the symptoms in Criteria A and C arise as a side effect of medication.
  4. The diagnosis of delirium should also specify if the level of psychomotor activity is hyperactive, hypoactive or mixed level activity.

Risk Factors and Comorbidity of Delirium

Delirium is strongly associated with underlying medical conditions and mental disorders. It is associated with neurological disorders and substance abuse, including medication. To treat delirium in persons undergoing alcohol or drug withdrawal, psychotics such as benzodiazepine are used. These psychotics can also trigger delirium in the withdrawal stage. Thus for proper treatment, the underlying disorders and overlapping symptoms must be identified.

A higher incidence of delirium is seen in diseases more prevalent in the elderly, such as Alzheimer’s, Parkinson’s and Huntington’s disease. The relation between the incidence of delirium and age is clearly delineated in the DSM-5. The prevalence of delirium of 1-2% in the general population rises to 14-24% in persons hospitalized and 70-80% in those in intensive care. Delirium increases with age with 83% of people experiencing delirium towards the end of life. Those in the final stages of an illness are often admitted to hospitals for the progression of the delirium rather than the underlying illness. In individuals hospitalized with delirium and an underlying medical condition, 40% die within the year, according to the DSM-5 (APA, 2013). Throughout the lifespan, delirium is associated with poorer health outcomes and functioning.

In the elderly population, distinguishing the overlap among symptoms of delirium and neurocognitive disorders is the greatest diagnostic challenge. In particular, dementia and delirium need to be clearly differentiated to improve the treatment outcome. Other common overlapping symptoms of delirium with other disorders include the presence of hallucinations and delusions in bipolar, depressive, and other psychotic disorders. And the anxiety and dissociative symptoms shared with acute stress disorder.

Treatment of Delirium

Pharmacotherapy is the main treatment for delirium. Psychotics are the most commonly prescribed medication. To improve the treatment of delirium and co-morbid symptoms and disorders, DSM-5 requires that the underlying cause – a disorder, substance or medication – be cited with the diagnostic code (e.g., the drug class for medication).

While delirium often self resolves, research shows that leaving it untreated increases the risk of heath complications, including respiratory insufficiency and infections, and mortality. A challenge in the treatment of delirium is weighing the benefits of medication with potential side effects and the risk that the medication itself may have a deleterious effect. The use of sedation in the treatment of PTSD has produced delusional memories in patients. A less sedated and more alert patient, in contrast, shows lower levels of delirium and more positive participation in physical and other forms of therapy (Devlin, 2013). Another concern of medication is its disturbance of the sleep-wake cycle, a condition associated with delirium that could be further aggravated.

The side effect and dependency risks of medications is a major drawback of pharmacotherapy in the treatment of delirium. A focus of research is applying other forms of therapy alongside pharmacotherapy with a view to improving symptoms and reducing the medication dose. A Korean team applying light therapy with risperidone found improvements in delirium scores and sleep time and efficiency (Yang, 2012). A Japanese study administering exercise therapy alongside antipsychotics was able to significantly lower the administered dose in the exercise group (Tatematsu, Hayashi, Narita, Tamaki, & Tsuboyama, 2011). In another study, cognitively stimulating activities produced improvements in delirium and attention and a smaller decrease in physical and mental functioning compared to a control group (Kolanowski, 2011).


American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). Arlington, VA: American Psychiatric Publishing.

Devlin, J. W., Fraser, G. L., Ely, E. W., Kress, J. P., Skrobik, Y., & Dasta, J. F. (2013). Pharmacological management of sedation and delirium in mechanically ventilated ICU patients: remaining evidence gaps and controversies. Semin Respir Crit Care Med, 34(2), 201-215.

Heymann, A., Radtke, F., Schiemann, A. E., Lütz, A., MacGuill, M., Wernecke, K. D., & Spies, C. (2010). Delayed treatment of delirium increases mortality rate in intensive care unit patients. Journal of International Medical Research, 38(5), 1584-1595.

Kolanowski, A. M., Fick, D. M., Clare, L., Steis, M., Boustani, M., & Litaker, M. (2011). Pilot study of a nonpharmacological intervention for delirium superimposed on dementia. Research in gerontological nursing, 4(3), 161-167.

Tatematsu, N., Hayashi, A., Narita, K., Tamaki, A., & Tsuboyama, T. (2011). The effects of exercise therapy on delirium in cancer patients: a retrospective study. Supportive Care in Cancer, 19(6), 765-770.

Yang, J., Choi, W., Ko, Y. H., Joe, S. H., Han, C., & Kim, Y. K. (2012). Bright light therapy as an adjunctive treatment with risperidone in patients with delirium: a randomized, open, parallel group study. General hospital psychiatry, 34(5), 546-551.

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