Delirium: an update on diagnosis, treatment and prevention.

been recognised as a mental disorder with serious adverse outcomes for thousands of years. Consistent descriptions of the condition have appeared in the medical literature from the time of Hippocrates. It is even described frequently in fictional literature, epitomising serious illness and often portending death. Despite this long history, delirium has been relatively neglected in healthcare settings. Clinicians consistently underdiagnose it and vary greatly in its management.1 Even worse, it is recognised that healthcare systems and services frequently have attributes that unintentionally precipitate or worsen delirium.2,3 Some of these include frequent changes of environment, routines which disrupt normal day/night rhythms (with a lack of exercise during the day and disturbance from noise and light at night) and exposure to infection risks. There is little published research: as an illustration, a word search for ‘delirium’ (excluding delirium tremens) on the Medline database (from 1966 to end of May 2006) yielded 3,181 results compared with 47,349 for myocardial infarction and 46,836 for stroke. Research has historically been impeded by difficulties in case definition and lack of agreement on diagnostic tools, as well as the problems inherent in studying patients who are often debilitated and lack mental capacity.1,4 This situation is improving following the publication of broadly similar ICD 10 and DSM IV criteria and greater consensus in diagnostic methods. There are still few trials of interventions for delirium, but taken together the evidence base is now sufficiently robust to provide clear directions for clinicians in detection, management and prevention of delirium.2