Objective: The phenotypes of several psychiatric conditions can very closely resemble delirium; the authors describe such presentations as pseudodelirium. However, because the clinical management of these conditions differs markedly from that of delirium, prompt differentiation is essential. The authors provide an educational review to assist clinicians in identifying and managing psychiatric conditions that may be especially challenging to differentiate from delirium.
Methods: Based on clinical experience, the authors identified four psychiatric conditions as among the most difficult to differentiate from delirium: disorganized psychosis, Ganser syndrome, delirious mania, and catatonia. An overview of each condition, description of clinical features, differentiation of specific phenotypes from delirium, and review of clinical management are also provided.
Results: The thought and behavioral disorganization in disorganized psychosis can be mistaken for the clouded sensorium and behavioral dysregulation encountered in delirium. The fluctuating alertness and apparent confusion in Ganser syndrome resemble delirium's altered arousal and cognitive features. As its name suggests, delirious mania presents as a mixture of hyperactive delirium and mania; additional features may include psychosis, autonomic activation, and catatonia. Both delirium and catatonia have hypokinetic and hyperkinetic variants, and the two syndromes can also co-occur.
Conclusions: The clinical presentations of several psychiatric conditions can blend with the phenotype of delirium, at times even co-occurring with it. Detailed evaluation is often required to differentiate such instances of pseudodelirium from delirium proper.
Keywords: Altered Mental Status; Catatonia; Cognitive Disorders; Delirious Mania; Delirium.