Table 1.

Comparison of features of various psychiatric presentations and deliriuma^a

Feature	Presentation
	Delirium	Dementia	Mania	Depression	Schizophrenia	Anxiety states	Personality disorder
Onset	Abrupt	Chronic	Can be acute	Subacute	Insidious	Chronic or acute in context of major stressor	Chronic with acute exacerbation of symptoms and/or decompensation in context of stressors
Delusions	Persecutory; fleeting, changeable, poorly formed; first-rank symptoms uncommon	Delusions can develop, generally late-stage, simple and persecutory	Grandiose, ‘mood congruent’	Nihilistic or persecutory ‘mood congruent’	Fixed, false system of beliefs with complex logical structure; ‘first-rank symptoms’	Absent	Although can have ‘overvalued ideas’, true delusions absent
Hallucinations	Predominantly visual	Both auditory and visual can occur in later disease (visual common in Lewy body dementia)	If present, generally auditory and ‘mood congruent’	If present, generally auditory, ‘mood congruent’	Auditory hallucination core feature, especially ‘third person’	Absent	Not true hallucinations; ‘pseudohallucinations’
Attention and/or working memory	Impaired	Relatively normal until advanced stages	Distractible, but attentional impairment less pronounced than delirium	Minimal impairment, although poor motivation can result in poor performance on assessment	Relatively intact	Intact	Intact
Arousal	Abnormal: hypoalert or hyperalert	Relatively normal	Hyperalert	May be hypoalert	Relatively normal or mildly hyperalert	Relatively normal or hyperalert in panic	Normal or mildly hyperalert
Orientation	Generally disorientated to time and often place	Disorientated in advanced cases	Orientated	Orientated	Orientated	Orientated	Orientated
Episodic memory	Impaired	Impaired, temporal gradient to memory loss	Relatively intact	Selective or patchy impairment, might complain about memory impairment	Relatively intact	Intact	Intact
Motor activity	Increased or decreased	Varies, often normal	Increased	Generally decreased	Generally fairly normal, although might be apathetic and can be catatonic	Often increased	Normal unless acutely agitated
Affect	Labile, although might be fearful or seem depressed	Variable	Elevated mood, although might be irritable and labile	Sustained low mood	Perplexed	Anxious	Anger
Speech	Slow and/or rapid, incoherent	Word finding difficulty but reasonably coherent until late stage	Pressured, ‘flight of ideas’	Slowed, monotonous	Disjointed, ‘loosening of association’	Relatively normal, might be slightly pressured	Normal
Sleep–wake cycle	Very disturbed, cycle can be reversed	Some fragmentation	Reduced sleep without sleepiness	Disturbed, often early-morning wakening	Relatively normal, although sleep-phase disorders common (especially delayed)	Initial insomnia characteristic	Relatively normal
Course	Fluctuating, lucid intervals can mislead	Stable from day to day	Alternate between elation and irritability	Diurnal variation in mood, worst in morning	Stable once established with deterioration generally consequent to medication non-compliance	Stable with potential episodes of panic	Stable

↵^aLewy body dementia poses particular difficulties in distinguishing from delirium given that visual hallucinations are prominent, the course is fluctuating and consciousness can be impaired.