Delirium differential diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Pratik Bahekar, MBBS [2]; Vishal Khurana, M.B.B.S., M.D. [3]

Overview

Delirium is differentiated from other causes cognitive dysfunction such as psychiatric Disorders, dementia. Unlike dementia, the course of delirium is reversible with fluctuation in level of consciousness.

Shown below the table of differentiating delirium from other psychiatric disorders:^[1]^[2]^[3]

**The difference between delirium and similar psychiatric illness**
Attributes	Delirium	Alzheimer 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)	May be present if associated with psychotic features	Present
Delusions	Fleeting	Mostly not present	May be present	Present
Psychomotar 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

Psychotic disorders: Delirium may be distinguished from psychosis, in which consciousness and cognition may not be impaired (however, there may be overlap, in acute psychosis, especially with mania, is capable of producing delirium-like states).
Delirium must be differentiated from following psychiatric disorders which have psychotic features.

Mania should be differentiated from hyperactive delirium.
Previous history of bipolar disorder is useful in distinguishing delirium from mania.
Acute stress disorder: Delirium accompanied by fear, anxiety, and dissociative symptoms must be differentiated from acute stress disorders.
Malingering and factitious disorder.
Confusional states: Delirium is distinguished by time-course from the confusion and lack of attention which result from long term learning disorders and varieties of congenital brain dysfunction.
Delirium is not the same as confusion, although the two syndromes may overlap and be present at the same time.
However, a confused patient may not be delirious (an example would be a stable, demented person who is disoriented to time and place), and a delirious person may not be confused (for example, a person in severe pain may not be able to focus because of the pain, and thus be by definition delirious, but may be completely oriented and not at all confused).
Other neurocognitive disorders: Sometimes delirium is superimposed on underling neurocognitive disorders such as dementia.^[5]

Delirium is distinguished from dementia (chronic organic brain syndrome) which describes an “acquired” (non-congenital) and usually irreversible cognitive and psychosocial decline in function.
Dementia usually results from an identifiable degenerative brain disease (for example Alzheimer disease or Huntington disease).
Dementia is usually not associated with a change in the level of consciousness, and a diagnosis of dementia requires a chronic impairment.
Sundowning: In [[patients] suffering from dementia or delirium which is an impairment in behavioral patterns in the evening hours.^[6]

Frontal lobe disorders such as tumors can produce deficits in memory, distorted emotional responses, impaired judgment.
Imaging studies and focal neurological symptoms may be helpful to differentiate from delirium.
Temporal lobe disorders may lead to memory deficits, cortical deafness, visual agnosia.
Imaging studies and focal neurological symptoms may be helpful to differentiate from delirium.
Occipital lobe disorders can demonstrate various symptoms such as confabulation, cortical blindness.
Imaging studies and focal neurological symptoms may be helpful to differentiate from delirium.
Parietal lobe disorders like Wernicke’s aphasia can hinder a patient’s ability to follow examiner’s instructions which are often misinterpreted as a state of confusion.
Nonconvulsive epileptic episodes should also be considered as a differential diagnosis of delirium.
- Delirium represents an organically caused decline from a previously attained level of cognitive functioning.

↑ Fong TG, Vasunilashorn SM, Libermann T, Marcantonio ER, Inouye SK (June 2019). “Delirium and Alzheimer disease: A proposed model for shared pathophysiology”. Int J Geriatr Psychiatry. 34 (6): 781–789. doi:10.1002/gps.5088. PMC 6830540 Check |pmc= value (help). PMID 30773695.
↑ O’Sullivan R, Inouye SK, Meagher D (September 2014). “Delirium and depression: inter-relationship and clinical overlap in elderly people”. Lancet Psychiatry. 1 (4): 303–11. doi:10.1016/S2215-0366(14)70281-0. PMC 5338740. PMID 26360863.
↑ Charlton, B.G; Kavanau, J.L (2002). “Delirium and psychotic symptoms – an integrative model”. Medical Hypotheses. 58 (1): 24–27. doi:10.1054/mehy.2001.1436. ISSN 0306-9877.
↑ “Delirium in elderly adults: diagnosis, prevention and treatment”.
↑ Fong TG, Davis D, Growdon ME, Albuquerque A, Inouye SK (August 2015). “The interface between delirium and dementia in elderly adults”. Lancet Neurol. 14 (8): 823–832. doi:10.1016/S1474-4422(15)00101-5. PMC 4535349. PMID 26139023.
↑ Canevelli M, Valletta M, Trebbastoni A, Sarli G, D’Antonio F, Tariciotti L, de Lena C, Bruno G (2016). “Sundowning in Dementia: Clinical Relevance, Pathophysiological Determinants, and Therapeutic Approaches”. Front Med (Lausanne). 3: 73. doi:10.3389/fmed.2016.00073. PMC 5187352. PMID 28083535.