A comparison of etiological and phenomenological profile across motor subtypes of delirium in a multi-site international database.

While the concept of delirium or acute confusional state dates back for centuries, it was first formally recognised under the heading of delirium in the Diagnostic and Statistical Manual (DSM III) third edition (1980). Previously it was denoted by more than thirty different syndromes, largely based on the clinical setting in which the symptoms occurred. Perhaps predictably, the amalgamation of what were once separate syndromes under the umbrella term of delirium led to considerable heterogeneity in terms of symptomatology, etiology, treatment and prognosis of this condition. 

Despite an extensive amount of research conducted in this field since this time, there remain large gaps in our knowledge as to what causes delirium and how it should be managed. In an effort to account for the heterogeneity of delirium, while continuing to view it as a unitary syndrome, recent research has focused on breaking it down into distinct motor subtypes. These comprise three broad subtypes: Hyperactive, hypoactive and mixed delirium, based on the activity levels and level of agitation of the delirious patient. The success of this subtyping method has led to the inclusion of delirium motor subtypes as other specifiers of delirium in the fifth edition of the DSM (DSM V).

A key issue with research of delirium motor subtypes is that it has tended to take place in a particular clinical setting (e.g., Intensive Care Unit, Medical unit, Palliative care etc) making the generalisability of results more difficult. Studies comprising large samples and taking place in multiple clinical settings have so far been lacking. One of the aims of the current study is to conduct a comprehensive study of the etiology and phenomenology of delirium motor subtypes across a large sample of patients from different clinical settings and to look at how dementia affects the presentation of delirium motor subtypes across these settings. This is an important area that remains poorly understood and has clinical implications in terms of patient’s management and prognosis.