Etiology of Delirium
- Indirect central nervous system effects related to systemic complications of cancer such as organ failure (e.g., hepatic or renal failure), metabolic or electrolyte disturbance (e.g., hypoglycemia, hypercalcemia, hyponatremia, or dehydration), infection, and paraneoplastic syndromes (e.g., bulbar encephalitis).
- Exogenous substances such as the wide variety of medications and treatments used in these patients, including most of the commonly used chemotherapeutic agents,[12-19] bone marrow or stem cell transplantation, biological response modifiers (e.g., interleukin and interferon), glucocorticoids, and especially psychoactive agents such as opioid analgesics, antidepressants, benzodiazepines, antihistamines, and other sedating agents.
- Withdrawal phenomena associated with substances such as alcohol and benzodiazepines.
Despite the very limited systematic study of risk factors for delirium in patients with cancer, risk factors have been identified in hospitalized elderly patients (some of them with cancer) and include the following:[20-22]
- Severe illness.
- Level of comorbidity.
- Advanced age.
- Prior dementia.
- Psychoactive medications.
Studies of hospitalized elderly patients suggest that the level of risk is proportionate to the number of risk factors present. Cancer is particularly prevalent in the elderly population. Many patients with cancer, particularly those with advanced disease, are likely to have a high level of baseline vulnerability. Such vulnerability leaves them predisposed to precipitants such as psychoactive medications. It is also likely that the predictors of poor pain control in cancer patients (neuropathic pain, incidental pain, opioid tolerance, somatization, and a history of drug or alcohol abuse) result in higher opioid doses and thereby increase the risk of delirium.
Distinct from delirium, older (65 years or older), long-term (>5 years) cancer survivors are also at increased risk of cognitive deficits and possibly dementia, as noted in a co-twin control design study of 702 Swedish cancer survivors.References
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