DSM-III

Diagnostic Criteria

A. Clouding of consciousness (reduced clarity of awareness of the environment), with reduced capacity to shift, focus, and sustain attention to environmental stimuli.

B. At least two of the following:

  1. perceptual disturbance: misinterpretations, illusions, or hallucinations
  2. speech that is at times incoherent
  3. disturbance of sleep-wakefulness cycle, with insomnia or daytime drowsiness
  4. increased or decreased psychomotor activity

C. Disorientation and memory impairment (if testable).

D. Clinical features that develop over a short period of time (usually hours to days) and tend to fluctuate over the course of a day.

E. Evidence, from the history, physical examination, or laboratory tests, of a specific organic factor judged to be etiologically related to the disturbance.

Differential Diagnosis

Psychotic Disorders

Schizophrenia, Schizophreniform Disorder, and other psychotic disorders may also be marked by hallucinations, delusions, and disordered thinking and speech. In Delirium, however, these symptoms are extremely random and haphazard, without evidence of systematization. The course fluctuates, and there is evidence of a clouded state of consciousness with global cognitive impairment. Finally, in Delirium there is often a generalized slowing of background activity in the electroencephlogram, and the syndrome's cause is obviously organic.

Dementia

Whereas Dementia involves a global cognitive deficit occurring in a normal state of consciousness, Delirium is basically a clouded state of consciousness. Often, however, the two syndromes coexist in the same individual, and it may be difficult to decide how much of the clinical picture to ascribe to one syndrome and how much to the other. One cannot diagnose Dementia in the presence of significant Delirium, because the symptoms of Delirium interfere with the proper assessment of Dementia. Only a definite history of pre-existing Dementia allows one to decide that an individual with Delirium also has Dementia. When there is uncertainty as to whether the symptoms in a given individual are basically those of Delirium or Dementia, it is best to make a provisional diagnosis of Delirium. This should lead to a more active therapeutic approach, and with time the proper diagnosis will become apparent.

Factitious Disorder

Factitious Disorder, with Psychological Symptoms simulating an Organic Brain Syndrome might, under rare circumstances, present a problem in the differential diagnosis of Delirium. The individual with Factitious Disorder shows inconsistencies in tests of mental status. A normal electroencephalogram also helps to exclude Delirium.

DSM-IV

Disorders

  1. Delirium Due to a General Medical Condition
  2. Substance-Induced Delirium
    1. Substance Intoxication Delirium
    2. Substance Withdrawal Delirium
  3. Delirium Due to Multiple Etiologies
  4. Delirium NOS

Differential Diagnosis

Dementia

The most common differential diagnostic issue is whether the person has a dementia rather than a delirium, has a delirium alone, or has a delirium superimposed on a preexisting dementia. Memory impairment is common to both a delirium and a dementia, but the person with a dementia alone is alert and does not have the disturbance in consciousness that is characteristic of a delirium. When symptoms of a delirium are present, information from family members, other caretakers, or medical records may be helpful in determining whether the symptoms of a dementia were preexisting.

Other Deliriums

The presumed etiology determines the specific delirium diagnosis. If it is judged that the delirium is a consequence of the direct physiological effects of a general medical condition, then Delirium Due to a General Medical Condition is diagnosed. If the delirium results from the direct physiological effects of a drug of abuse, then Substance Intoxication Delirium or Substance Withdrawal Delirium is diagnosed, depending on whether the delirium occurred in associated with Substance Intoxication or Substance Withdrawal. If the delirium results from medication use or toxin exposure, then Substance-Induced Delirium is diagnosed. It is not uncommon for the delirium to be due to both a general medical condition and substance (including medication) use. This may be seen, for example, in an elderly individual with a serious general medical condition that is being treated with multiple medications. When there is more than one etiology (e.g., both a substance and a general medical condition), Delirium Due to Multiple Etiologies is diagnosed. If it is not possible to establish a specific etiology (i.e., substance induced or due to a general medical condition), Delirium Not Otherwise Specified is diagnosed.

Substance Intoxication or Withdrawal

This diagnosis of Substance Intoxication Delirium or Substance Withdrawal Delirium is made instead of Substance Intoxication or Substance Withdrawal only if the symptoms of the delirium are in excess of those usually associated with the intoxication or withdrawal syndrome and are sufficiently severe to warrant independent clinical attention. Even in individuals with obvious signs of intoxication or withdrawal, other possible causes of the delirium (i.e., Delirium Due to a General Medical Condition) must not be overlooked. For example, a head injury that occurs as a result of falls or fighting during intoxication may be responsible for the delirium.

Psychotic Disorders

Delirium that is characterized by vivid hallucinations, delusions, language disturbances, and agitation myst be distinguished from Brief Psychotic Disorder, Schizophrenia, Schizophreniform Disorder, and other Psychotic Disorders, as well as from Mood Disorders With Psychotic Features. In delirium, the psychotic symptoms fluctuate, are fragmented and unsystematized, occur in the context of a reduced ability to appropriately maintain and shift attention, and are usually associated with EEG abnormalities. There is often memory impairment and disorientation in delirium, but generally not in these other disorders. Finally, in delirium, the person generally shows evidence of an underlying general medical condition, Substance Intoxication or Withdrawal, or medication use.

Malingering and Factitious Disorder

Delirium must be distinguished from Malingering and from Factitious Disorder. This distinction is made based on the often atypical presentation in Malingering and Factitious Disorder and the absence of a general medical condition or substance that is etiologically related to the apparent cognitive disturbance.

Cognitive Disorder Not Otherwise Specified

Individuals may present with some but not all symptoms of delirium. Subsyndromal presentations need to be carefully assessed because they may be harbingers of a full-blown delirium or may signal an as yet undiagnosed underlying general medical condition. Such presentations should be recorded as Cognitive Disorder Not Otherwise Specified.

DSM-5

Diagnostic Criteria

A. A disturbance in attention (i.e., reduced ability to direct, focus, sustain, and shift attention) and awareness (reduced orientation to the environment).

B. 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.

C. An additional disturbance in cognition (e.g., memory deficit, disorientation, language, visuospatial ability, or perception).

D. 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 severity reduced level of arousal, such as coma.

E. 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.

Specify whether:

  • Substance intoxication delirium: This diagnosis should be made instead of a substance intoxication when the symptoms in Criteria A and C predominate in the clinical picture and when they are sufficiently severe to warrant clinical attention.
    • If a mild substance use disorder is comorbid with the substance intoxication delirium, the clinician should record "mild [substance] use disorder" before the substance intoxication delirium (e.g., "mild cocaine use disorder with cocaine intoxication delirium"). If a moderate or severe substance use disorder is comorbid with the substance intoxication delirium, the clinician should record "moderate [substance] use disorder" or "severe [substance] use disorder," depending on the severity of the comorbid substance use disorder. If there is no comorbid substance use disorder (e.g., after a one-time heavy use of the substance), then the clinician should record only the substance intoxication delirium.
  • Substance withdrawal delirium: This diagnosis should be made instead of substance withdrawal when the symptoms in Criteria A and C predominate in the clinical picture and when they are sufficiently severe to warrant clinical attention.
  • Medication-induced delirium: This diagnosis applies when the symptoms in Criteria A and C arise as a side effect of a medication taken as prescribed.
  • Delirium due to another medical condition: There is evidence from the history, physical examination, or laboratory findings that the disturbance is attributable to the physiological consequences of another medical condition.
    • Include the name of the other medical condition in the name of the delirium (e.g., delirium due to hepatic encephalopathy). The other medical condition should also be listed separately immediately before the delirium due to another medical condition (e.g., hepatic encephalopathy; delirium due to hepatic encephalopathy).
  • Delirium due to multiple etiologies: There is evidence from the history, physical examination, or laboratory findings that the delirium has more than one etiology (e.g., more than one etiological medical condition; another medical condition plus substance intoxication or medication side effect).
    • Note: Use multiple separate diagnoses reflecting specific delirium etiologies (e.g., hepatic encephalopathy, delirium due to hepatic failure; alcohol withdrawal delirium). Note that the etiological medical condition both appears as a separate recording that preceded the delirium and is substituted into the delirium due to another medical condition rubric.

Specify if:

  • Acute: Lasting a few hours or days.
  • Persistent: Lasting weeks or months.

Specify if:

  • Hyperactive: The individual has a hyperactive level of psychomotor activity that may be accompanied by mood lability, agitation, and/or refusal to cooperate with medical care.
  • Hypoactive: The individual has a hypoactive level of psychomotor activity that may be accompanied by sluggishness and lethargy that approaches stupor.
  • Mixed level of activity: The individual has a normal level of psychomotor activity even though attention and awareness are disturbed. Also includes individuals whose activity level rapidly fluctuates.

Recording Procedures

Substance intoxication delirium

The name of the substance/medication intoxication delirium begins with the specific substance (e.g., cocaine, dexamethasone) that is presumed to be causing the delirium. In cases in which a substance is judged to be an etiological factor but the specific class of substance is unknown, the category "unknown substance" should be used.

When recording the name of the disorder, the comorbid substance use disorder (if any) is listed first, followed by the word "with," followed by the name of the substance intoxication delirium, followed by the course (i.e., acute, persistent), followed by the specifier indicating level of psychomotor activity (i.e., hyperactive, hypoactive, mixed level of activity). For example, in the case of acute hyperactive intoxication delirium occurring in a man with a severe cocaine use disorder, the diagnosis is severe cocaine use disorder with cocaine intoxication delirium, acute, hyperactive. A separate diagnosis of the comorbid severe cocaine use disorder is not given. If the intoxication delirium occurs without a cormorbid substance use disorder (e.g., after a one-time heavy use of the substance), no accompanying substance use disorder is noted (e.g., phencyclidine intoxication delirium, acute, hypoactive).

Substance withdrawal delirium

The name of the substance/medication withdrawal delirium begins with the specific substance (e.g., alcohol) that is presumed to be causing the withdrawal delirium. When recording the name of the disorder, the comorbid moderate or severe substance use disorder (if any) is listed first, followed by the course (i.e., acute, persistent), followed by the specifier indicating level of psychomotor activity (i.e., hyperactive, hypoactive, mixed level of activity). For example, in the case of acute hyperactive withdrawal delirium occurring in a man with a severe alcohol use disorder, the diagnosis is severe alcohol use disorder with alcohol withdrawal delirium, acute, hyperactive. A separate diagnosis of the comorbid severe alcohol use disorder is not given.

Medication-induced delirium

The name of the medication-induced delirium begins with the specific substance (e.g., dexamethasone) that is presumed to be causing the delirium. The name of the disorder is followed by the course (i.e., acute, persistent), followed by the specifier indicating level of psychomotor activity (i.e., hyperactive, hypoactive, mixed level of activity). For example, in the case of acute hyperactive medication-induced delirium occurring in a man using dexamethasone as prescribed, the diagnosis is dexamethasone-induced delirium, acute, hyperactive.

Specifiers

Regarding course, in hospital settings, delirium usually lasts about 1 week, but some symptoms often persist even after individuals are discharged from the hospital.

Individuals with delirium may rapidly switch between hyperactive and hypoactive states. The hyperactive state may be more common or more frequently recognized and often is associated with medication side effects and drug withdrawal. The hypoactive state may be more frequent in older adults.

Differential Diagnosis

Psychotic disorders and bipolar and depressive disorders with psychotic features

Delirium that is characterized by vivid hallucinations, delusions, language disturbances, and agitation must be distinguished from brief psychotic disorder, schizophrenia, schizophreniform disorder, and other psychotic disorders, as well as from bipolar and depressive disorders with psychotic features.

Acute stress disorder

Delirium associated with fear, anxiety, and dissociative symptoms, such as depersonalization, must be distinguished from acute stress disorder, which is precipitated by exposure to a severely traumatic event.

Malingering and factitious disorder

Delirium can be distinguished from these disorders on the basis of the often atypical presentation in malingering and factitious disorder and the absence of another medical condition or substance that is etiologically related to the apparent cognitive disturbance.

Other neurocognitive disorders

The most common differential diagnostic issue when evaluating confusion in older adults is disentangling symptoms of delirium and dementia. The clinician must determine whether the individual has delirium; a delirium superimposed on a preexisting NCD, such as due to Alzheimer's disease; or an NCD without delirium. The traditional distinction between delirium and dementia according to acuteness of onset and temporal course is particularly difficult in those elderly individuals who had a prior NCD that may not have been recognized, or who develop persistent cognitive impairment following an episode of delirium.

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