Onset

Acute

Often insidious

Variable

Variable

Course

Fluctuating

Often progressive

Diurnal variation

Variable

Reversibility

Usually

Not usually

Usually, but can be recurrent

No

Level of consciousness

Impaired

Clear until late stages

Usually unimpaired

Not impaired, but perplexity seen in acute illness

Attention/memory

Poor memory and attention

Poor memory without marked inattention

Poor attention, memory intact

Poor attention, memory intact

Hallucinations

Usually vivid visual and tactile; but any modality possible

Visual or auditory

Usually auditory

Usually auditory

Delusions

Fleeting, fragmented, usually persecutory with local context (e.g., hospital is a prison)

Paranoid, often fixed

Complex and mood congruent

Frequent, complex, systematized, often paranoid

Modified from Hales RE, Yudofsky SC, eds. Essentials of Neuropsychiatry and Clinical Neurosciences. Washington, DC: American Psychiatric Publishing, Inc; 2004:144, with permission.