ABSTRACT
Impairment of consciousness is the primary and universal clinical change occurring in acute brain disease. Delirium lies on the continuum between full consciousness and deep coma. Consciousness is that state of an organism that enables cognitive processes to occur. The acute onset of psychiatric symptoms in a person with compromised physical health is a necessary prerequisite for a diagnosis of delirium. Diagnosing delirium is essentially that of a bedside clinical judgement. Criteria for uniformity, predominantly for research purposes, may be useful additions to clinical practice as screening and confirmatory tools. There is a multiplicity of such scales, all with attractions and limitations. The Mini Mental State Examination quantifies the impairments but does not distinguish delirium from dementia. The medication of first choice for delirium is an antipsychotic. The mechanism of action of these medications in delirium is uncertain. There are particular forms of delirium in which antipsychotic medication is not the treatment of first choice.
