Delirium vs dementia vs depression

Confusion in an older adult is one of the most consequential differentials a counselor faces: delirium is a medical emergency, dementia (major neurocognitive disorder) is progressive, and depression with cognitive complaints is treatable. The exam skill is choosing among them from onset, course and attention.

Delirium (paraphrased). A disturbance in attention (directing, focusing, sustaining, shifting) and awareness that develops over a short period (usually hours to a few days), represents a change from baseline, and fluctuates in severity during the day. There is an additional cognitive disturbance (memory, orientation, language, perception). It is not better explained by a preexisting NCD and not in the context of severely reduced arousal such as coma, and there is evidence of a medical cause, substance intoxication or withdrawal, or medication effect. Specifiers: acute vs persistent; hyperactive, hypoactive or mixed activity level. Hypoactive delirium (quiet, withdrawn, slowed) is easily mistaken for depression.

Dementia (major NCD). Insidious onset, gradual progression over months to years, attention intact early, consciousness clear. Clients often minimize or lack awareness of deficits and tend to try hard on testing.

Depression with cognitive complaints (sometimes called pseudodementia). Onset coincides with mood symptoms, deficits fluctuate with mood, clients emphasize and describe their lapses in detail, give "I don't know" answers with low effort, and show depressed mood, anhedonia and psychomotor slowing. Cognition often improves when depression is treated, though persistent deficits warrant further evaluation.

Hinge facts.

• Delirium vs dementia: acute onset and fluctuating attention/consciousness mean delirium.
• Dementia vs depression: depression's complaints exceed measured deficits and track mood; dementia's deficits exceed complaints and progress regardless of mood.
• Delirium can sit on top of dementia, and depression can co-occur with early NCD.

On the NCMHCE. Sudden confusion, disorientation or hallucinations in an older adult call for immediate medical referral: infections (urinary tract infection is a classic trigger), medication changes (especially anticholinergic or sedating drugs), dehydration, alcohol or sedative withdrawal, and metabolic problems. Obtain collateral on baseline functioning and timeline. Screen cognition (MoCA, MMSE) and mood (Geriatric Depression Scale) as screens only; normal labs that rule out thyroid or B12 problems do not settle depression vs NCD. When depression is likely, treat it first; refer for neuropsychological evaluation if cognitive complaints persist after the mood remits. Always screen suicide risk in older adults with depression, and assess safety, caregiver capacity and elder abuse.

Clinical Pearl: Acute + fluctuating attention = delirium = medical emergency. Depression complains of deficits; dementia minimizes them and progresses.