Purpose of review: Since the publication of DSM-III in 1980, the essential criteria for delirium have been reduced progressively through DSM-III-R to DSM-IV. As the field moves toward DSM-V and ICD-11, new data can shed light on the nosological changes that are needed so that diagnostic criteria can reflect empirical data. In this study, we reassess the existing or potential criteria for delirium.
Recent findings: Phenomenological studies in recent years have informed the criteria for delirium, including the appropriateness of the term 'consciousness' as a core symptom of the diagnosis, additional symptoms of delirium that are frequent but are not currently part of the diagnostic criteria, subsyndromal delirium, motoric subtypes of delirium (hyperactive, hypoactive), and the association of delirium with dementia.
Summary: Recent studies suggest that motoric subtypes should be included as a subtype for delirium but that subsyndromal delirium, although a useful research construct, should not be included in clinical diagnostic criteria given the frequent fluctuation in symptoms over short periods. In addition, though the core symptoms are probably adequate to make the diagnosis, clinicians must be aware of the frequency of other symptoms, for symptoms such as profound sleep disturbance or psychotic symptoms may dominate the clinical picture.