Dementia, Delirium and Depression

Table 1: Classical differentiating features of delirium, dementia and depression





Onset Hours to days Months to years Weeks to months
Pattern Fluctuant throughout the day

Progressive over time

Often worse at night


Often worse in the morning

Areas of impairment Global At least two areas affected Specific impairments within several areas of function
Alertness Often impaired Often normal Often normal
Affect Often agitated but can be hypoactive Dependent on subtype or severity Flattened
Course Reversible Irreversible over time Reversible

As already discussed, there can be considerable overlap between dementia, delirium and depression.

Delirium is an acute, reversible organic mental syndrome characterised by reduced ability to maintain attention to external stimuli and disorganised thinking.

Depression is a mental state of depressed mood characterised by feelings of sadness, despair and discouragement.

This table describes the classical differentiating features of each.