Delirium as a disorder of consciousness

Abstract

Delirium is a common clinical phenomenon, often described as a disorder of consciousness. Delirium is commonly under recognised. The usual response to under recognition is to exhort practitioners to do a better job, but perhaps under recognition should instead be seen as a daily pragmatic challenge to how delirium is conceptualised. Here we retain the view that delirium is a disorder of consciousness, but propose a more multidimensional approach to this key feature. We argue that delirium can be recognised through evaluating arousal, attention and temporal orientation. We suggest that this approach can be validated by testing whether it leads to better delirium identification, accounts for the characteristic clinical disturbances, explains why delirium is common in the extreme age groups and why in later life its boundaries often blend with dementia.

Delirious Mania

“…Acetylcholine is the primary neurotransmitter of the ascending reticular activating system (RAS), 12 and consequently the hypocholinergic state in delirium results in reduced alertness and inattention. 13,14 Increased dopamine, either due to oxidative stress or dopaminergic medications, is thought to lead to perceptual disturbances and paranoia that are often associated with delirium. 15 Increased gamma-aminobutyric acid (GABA) signaling, in addition to its influence on acetylcholine and dopamine, 16 is also thought to interfere with sleep patterns and disrupt circadian rhythms and melatonin release, leading to the disturbed sleep seen in delirium.…”

Diagnosis and treatment of dementia: 2. Diagnosis

“…Delirium is a medical emergency with an increased risk for morbidity and death, and as such it is particularly significant in the differential diagnostic considerations. [27][28][29] It calls for immediate investigation and management of treatable medical conditions. Individuals with dementia are at risk for delirium; however, the initial diagnosis of dementia should not be made while the patient is in a delirious state.…”

Differential effects of delirium on fluid and crystallized cognitive abilities

“…Cognitive impairment is one of the core diagnostic features of delirium (American Psychiatric Association, 1994), although detailed characterization of this impairment is lacking (Bhat and Rockwood, 2007). What is known is that patients show marked attentional deficits (O'Keeffe and Gosney, 1997), and so are impaired on tasks that require 'fluid' cognitive processing; that is, tasks that involve active, flexible processing of neural information, such as retrieving, maintaining, or manipulating mental representations (Horn and Cattell, 1966;Craik and Bialystok, 2006).…”