Delirium is an acute state characterized by confusion and altered awareness, representing a sudden change in mental abilities. It develops rapidly, often within hours or days, affecting thinking, memory, and focus. Delirium is common among hospitalized individuals, particularly cancer patients.
Understanding Delirium in Cancer Patients
Delirium in cancer patients involves a disturbance in attention, awareness, and cognitive function. Symptoms often appear suddenly and tend to fluctuate throughout the day, sometimes worsening at night. Delirium can manifest in three main types: hyperactive, hypoactive, and mixed. Hyperactive delirium involves restlessness, agitation, and sometimes hallucinations, while hypoactive delirium presents as sluggishness, drowsiness, and reduced activity, often going unrecognized. Mixed delirium involves a fluctuation between hyperactive and hypoactive symptoms.
Cancer patients face a heightened susceptibility to delirium. Their underlying disease, complex treatment regimens, and often fragile health status contribute to this vulnerability. Delirium is a common neuropsychiatric syndrome in cancer patients, with incidence estimates ranging from 10% to 85% depending on the cancer stage and setting. In palliative care settings, the prevalence can be particularly high, reaching up to 88% in the last weeks of life. Recognizing delirium is important for addressing its underlying causes and managing its effects.
Direct Cancer-Related Causes
Cancer progression can directly lead to delirium. When cancer spreads to the brain, forming metastases, or when a primary brain tumor is present, it can directly impair cognitive function and brain activity. These tumors can cause swelling or disrupt normal brain processes, leading to changes in mental status.
Systemic effects of cancer, such as paraneoplastic syndromes, also contribute to delirium. These syndromes occur when the body’s immune response to cancer inadvertently attacks parts of the nervous system, leading to neurological symptoms. Furthermore, cancer can cause metabolic disturbances, including electrolyte imbalances, which significantly affect brain function. Hypercalcemia, an elevated calcium level often due to bone metastases, is a common electrolyte imbalance in cancer patients that can precipitate delirium. Other imbalances like hyponatremia (low sodium) or hypokalemia (low potassium) can also arise from the cancer itself or its complications, further contributing to a confused state.
Cancer Treatment-Related Causes
Various cancer treatments can induce delirium due to their systemic effects and direct impact on the nervous system. Chemotherapy agents can be neurotoxic, directly damaging brain cells or disrupting neurotransmitter balance, leading to cognitive changes and delirium. Radiation therapy, particularly to the brain, can cause inflammation, swelling, or direct damage to brain tissue, precipitating delirium. This is especially true for patients who received radiation within a year prior to other treatments.
Surgical procedures, common in cancer treatment, carry a risk of postoperative delirium (POD). Factors like the stress of surgery, anesthetic agents, and the inflammatory response following the procedure can contribute to POD. Older cancer patients undergoing surgery are particularly vulnerable to POD, with incidence rates potentially reaching up to 50%. Targeted therapies and immunotherapies, while precise in their action against cancer, can also trigger delirium. Immunotherapies, for instance, can lead to cytokine release syndrome, a systemic inflammatory response that can affect the brain and result in delirium.
These treatments can lead to delirium through various pathways, including direct neurotoxicity, systemic inflammation, and disturbances in electrolytes or organ function. The complex interplay of these effects makes cancer treatment a significant factor in the development of delirium.
Medication-Induced Causes
Many medications commonly prescribed to cancer patients for symptom management can induce delirium. Opioids, frequently used for pain relief, can alter mental status and contribute to confusion. The risk of delirium with opioid use is a recognized concern, especially with higher doses.
Benzodiazepines, prescribed for anxiety or sleep disturbances, are also known to precipitate or worsen delirium. While sometimes used in specific situations like terminal delirium with agitation, they are generally approached with caution due to their potential to exacerbate confusion. Corticosteroids, used for inflammation, appetite stimulation, or to manage treatment side effects, can induce delirium, sometimes referred to as steroid psychosis. High doses or prolonged use of corticosteroids, or even sudden discontinuation, can lead to this altered mental state.
Anticholinergic medications, found in various drug classes including some antihistamines and antiemetics, block the action of acetylcholine, a neurotransmitter important for cognition. This mechanism can lead to confusion and altered mental status, particularly in older patients. Other sedatives and antiemetics can also have central nervous system effects that contribute to delirium, making careful medication review important in cancer care.
General Medical Conditions and Environmental Factors
Several general medical conditions commonly seen in cancer patients can also contribute to delirium. Infections such as pneumonia, urinary tract infections, or sepsis can trigger a systemic inflammatory response that affects brain function. Metabolic imbalances, distinct from those directly caused by cancer, are frequent contributors. These include dehydration, low or high blood sugar, and other electrolyte disturbances like hyponatremia or hypokalemia, which can disrupt normal brain activity.
Organ failure, including renal, hepatic, or respiratory insufficiency, can lead to a buildup of toxins or insufficient oxygen delivery to the brain, resulting in delirium. Nutritional deficiencies, common in cancer patients due to disease burden or treatment side effects, can also impair brain function. These physiological stressors often combine to increase a patient’s susceptibility to delirium.
Environmental factors in healthcare settings further influence the risk of delirium. Sleep deprivation, often due to frequent interruptions for medical care, can disrupt the normal sleep-wake cycle and contribute to confusion. Sensory overload from constant noise and activity, or sensory deprivation from lack of familiar stimuli, can disorient patients. Changes in routine and the unfamiliarity of the hospital environment can also contribute to a patient’s vulnerability to developing delirium.