Clinical meaning
Delirium is an acute, fluctuating disturbance of consciousness and cognition caused by an underlying medical condition, medication, or substance. Its pathophysiology involves widespread cortical dysfunction from cholinergic deficiency, dopaminergic excess, neuroinflammation (elevated IL-6, TNF-alpha), and disruption of the blood-brain barrier. Delirium is reversible when the precipitating cause is identified and treated. Dementia, in contrast, is a chronic, progressive, irreversible decline in cognitive function affecting memory, executive function, language, and visuospatial ability. Alzheimer disease (60-80% of dementias) involves accumulation of extracellular beta-amyloid plaques and intracellular neurofibrillary tangles of hyperphosphorylated tau protein, leading to synaptic loss and neuronal death predominantly in the hippocampus and temporal cortex. Vascular dementia results from cumulative cerebrovascular ischemic injury. Delirium superimposed on dementia is common and worsens long-term cognitive trajectory.
Diagnosis & workup
Diagnostics & workup: - Confusion Assessment Method (CAM): acute onset + fluctuating course + inattention + (disorganized thinking OR altered consciousness) - Cognitive screening: Montreal Cognitive Assessment (MoCA) for dementia (score < 26/30 abnormal) - CBC, electrolytes, creatinine, glucose, calcium, TSH, urinalysis, blood cultures - Medication reconciliation (identify anticholinergic burden) - CT head if focal neurological signs, head trauma, or anticoagulant use - MRI brain with volumetry for dementia (hippocampal atrophy in Alzheimer disease)