The Neuropsychiatric Disturbances of Delirium: A Review of Syndromes and Their Treatment.

Broadly analogous to the behavioral and psychological symptoms that plague dementia, the neuropsychiatric disturbances (NPD) of delirium pose significant burdens to patients, their loved ones, and clinicians. Moreover, these disturbances are often the most salient aspect of delirium, causing distress and placing patients and those around them at risk of harm. The field's limited understanding of delirium's NPD could also be a key reason why the pharmacology of delirium remains underdeveloped. In this narrative review, we propose clinically relevant neuropsychiatric syndromes in delirium, along with provisional definitions. We then discuss evidence for potential pharmacological and nonpharmacological interventions for each, both within the context of delirium and in other conditions, especially where these syndromes also occur in dementia. Candidate syndromes include excessive psychomotor activity and the related akathisia; inadequate psychomotor activity, either as reduced arousal or as avolition; psychosis, including perceptual disturbances and erroneous beliefs; emotional disturbances, either as affective dysregulation or as anxious distress; catatonia; and sleep-wake disturbances. The NPD of delirium should be differentiated from the global cognitive impairment of delirium as they often warrant independent clinical attention. The failure to tailor treatments to specific syndromes-for instance, treating akathisia in delirium with an antipsychotic, leading to greater behavioral activation-stands not only to prolong distress but also to worsen clinical outcomes. These syndromes deserve greater awareness and conceptual refinement to inform clinical management and to identify novel avenues for research.