I regularly see the subtypes of delirium in my work as a general hospital psychiatric consultant. I still get called to evaluate “severe depression” in patients who really have hypoactive delirium, which can mimic severe depression and apathy. Often enough (and sadly) doctors and nurses fail to recognize that hyperactive and hypoactive delirium are the same syndrome with respect to the core features which include difficulties focusing, shifting, and sustaining attention. Rain is still rain, storm or drizzle.
Subtypes of delirium are another way for this entity to mimic other psychiatric diagnostic categories–and represent a distinct challenge, which is the need to be vigilant for delirium. Delirium can even look like a catatonia, and it’s been suggested that there could be a catatonic subtype of delirium. Hypoactive delirium and catatonia can look a lot alike but the hyperactive catatonic patient, who may exhibit purposeless agitation, may also segue to and from a display of more “classic” delirium features of obvious cognitive disorganization, fluctuating level of consciousness, and difficulties focusing attention. According to Francis and Lopez-Canino, catatonia is:
Catatonia is a well-characterized but often unrecognized syndrome with motor and behavioral signs. Among the most common signs are immobility, withdrawal, posturing, mutism, and negativism, which could be identified in hypoactive delirium. Similarly, impulsivity, mannerisms, excitement, and combativeness are signs of catatonia that may be associated with hyperactive delirium. Establishing the existence of a catatonic subtype of delirium may have implications for treatment, since patients with catatonia respond well to high-potency benzodiazepines, which are generally avoided in the treatment of delirium. Catatonia may worsen or progress to neuroleptic malignant syndrome with butyrophenones (such as haloperidol(Drug information on haloperidol)), which are frequently administered for delirium.
Hypoactive and hyperactive delirium, along with the commonly encountered “mixed” subtype all tend to share cognitive disorganization, and the tendency to shift between subtypes. Hyperactive delirium is often marked by terrifying fragmented hallucinations, delusions, striking mood lability, sleep disturbance, and incoherence–and so can hypoactive delirium if one is carefully looking for these features. As reported by Blazer and colleagues, hypoactive delirium can be missed in 76% of emergency room patients. Hypoactive delirium has been shown to have a higher mortality rate in older patients.
But the underlying theme is the same in these subtypes, which all tend to run together. Most of the time, delirium fluctuates and we’ll see a mixed picture. The most important thing is not to miss the chance to identify delirium, and not to mistake delirium for a primary psychiatric disorder.
Liptzin, B. and S. E. Levkoff (1992). “An empirical study of delirium subtypes.” Br J Psychiatry 161: 843-845.
Using a structured instrument, 325 elderly patients admitted to a general hospital for an acute medical problem were evaluated daily in order to detect symptoms of delirium. Patients were scored for ‘hyperactive’ or ‘hypoactive’ symptoms, and then the 125 patients with DSM-III delirium were rated as ‘hyperactive type’ (15%), ‘hypoactive type’ (19%), ‘mixed type’ (52%), or ‘neither’ (14%). There were no statistically significant differences between the groups with respect to age, sex, place of residence, or presence of dementia. These definitions of subtypes should be studied further.
Blazer, D. G. and A. O. van Nieuwenhuizen (2012). “Evidence for the diagnostic criteria of delirium: an update.” Curr Opin Psychiatry 25(3): 239-243.
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.
Francis, A., MD, PhD, and A. Lopez-Canino, MD (2009) Delirium with Catatonic Features: A New Subtype? Psychiatric Times