Delirium

Delirium is global cerebral dysfunction from a systemic or organic insult, not a primary psychiatric illness

The brain's arousal and attentional networks (the ascending reticular activating system and its cortical projections) are exquisitely sensitive to derangements in oxygenation, metabolism, inflammation and neurotransmission. Infection, hypoxia, metabolic disturbance, drugs and pain all converge on the same final common pathway: a relative excess of dopaminergic and glutamatergic activity with a deficit of cholinergic tone, destabilising the networks that maintain a coherent, sustained level of consciousness. Delirium is therefore always a symptom of something else, which is why 'find and treat the cause' is the entire management strategy, not one step among many.