Pharmacological interventions for preventing delirium in the elderly

Delirium is a common occurrence in older hospitalised patients, particularly in the setting of surgical intervention and acute illness. Delirium is associated with a number of adverse clinical and social outcomes with higher financial cost and risk of developing dementia, as well as increased likelihood of need for residential care. Current interventions for the prevention of delirium typically involve recognition and amelioration of modifiable risk factors and treatment of underlying conditions that predispose the individual to delirium. A number of pharmacological strategies for delirium prevention have been tested. Antipsychotic medications are used for treatment of agitation in the setting of delirium when other measures have failed, but their efficacy in prevention is limited by study heterogeneity and concerns about tolerability. Acetylcholinesterase inhibitors are effective in the symptomatic treatment of Alzheimer's disease but do not appear to be effective in preventing delirium. Melatonin and melatonin agonists have a rather benign side effect profile and show promise for prevention of delirium in medically unwell individuals. The alpha-2 agonist, dexmedetomidine may be helpful in the intensive care unit setting but intravenous route of administration and need for close clinical supervision limits its use in the wider hospital environment. Other agents such as benzodiazepines, corticosteroids, statins and gabapentin have been suggested but lack evidence to support their role in delirium prevention. To date, there is inconsistent and conflicting data regarding the efficacy of any particular pharmacological agent although some interventions do show promise. Larger, well-designed, placebo-controlled clinical trials are needed.