Evidence for the Diagnostic Criteria of Delirium

An Update

Dan G. Blazer; Adrienne O. van Nieuwenhuizen

Disclosures

Curr Opin Psychiatry. 2012;25(3):239-243. 

In This Article

Motoric Subtypes

Delirium is present in hyperactive, hypoactive, and mixed forms, which can be specified while recognizing that patients may rapidly switch from one type to another. One way to study these motoric subtypes is through accelerometer-based monitoring, though most investigations use observational data to make these specifications.[17] The hyperactive subtype[18,19] is often associated with medication side effects and drug withdrawal. Delusions, hallucinations, mood lability, speech incoherence, and sleep disturbances may be somewhat more frequent in hyperactive patients,[20] but can also occur in hypoactive patients. The hypoactive subtype may be more frequent in older adults but is not as easily recognized and therefore more easily dismissed as clinically irrelevant. Metabolic abnormalities such as hepatic toxicity and dehydration are often associated with the hypoactive subtype.[7] These patients may appear sluggish and lethargic as well as confused.

Yet the relative frequency of the subtypes may vary depending upon the setting. Ouimet et al.[21] found the overall prevalence of delirium in surgical and trauma patients to be 70%, with two-thirds of these being of the hypoactive type in both groups of patients. The prevalence of pure hyperactive delirium in this population was quite low. In another study,[22] hypoactive delirium was much more frequent in emergency departments and was missed by emergency room physicians in 76% of the cases.

Motoric subtypes have not been found to have consistent differences in cognitive functioning. Leonard et al.[23] assessed the neuropsychological and symptom profiles of 100 patients with DSM-IV delirium in a palliative care unit and categorized these patients according to motor subtypes: hypoactive (N = 33), hyperactive (N = 18), mixed (N = 26), and no alteration motor groups (N = 23). The mixed group had more severe delirium, with a higher frequency of sleep–wake cycle disturbance, hallucinations, delusions, and language abnormalities. Cognitive function, as assessed by the CTD, did not vary across the three subtypes of motoric abnormality, although patients with no motor alteration scores experienced less severe delirium.

Yang et al.[24] studied 441 older patients admitted with delirium to a postacute care facility. They used latent class analysis to identify four classes of psychomotor severity subtypes of delirium: hypoactive/mild; hypoactive/severe; mixed, with hyperactive features/severe; and normal/mild. In the study's follow-up period, they found that, in patients who also suffered from dementia, the hypoactive/mild class was associated with a higher risk of mortality. Among those without dementia, a greater severity was associated with higher mortality regardless of psychomotor features, when compared with the normal/mild class. Overall, it appears that delirium can be readily categorized into one of these motoric subtypes, and such categorization can be clinically useful given the variation in overall severity and presentation of other symptoms.

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