Delirium in hospitalized older adults is a sudden and severe change in mental status characterized by confusion, disorientation, and difficulty with attention and memory. It is not a disease itself but rather a syndrome caused by various underlying factors that disrupt brain function. Among older adults in hospitals, delirium is especially common due to their increased vulnerability from age-related changes and multiple health issues.
The most frequent causes of delirium in this population can be broadly grouped into several categories:
**1. Infections:**
Infections are one of the leading triggers of delirium among hospitalized elderly patients. Urinary tract infections (UTIs) are particularly common culprits because they often present atypically without classic symptoms like fever or pain but still cause significant systemic inflammation affecting the brain. Pneumonia and other respiratory infections also frequently precipitate delirium by causing hypoxia (low oxygen levels) or systemic illness.
**2. Metabolic disturbances:**
Metabolic imbalances are another major cause of delirium, sometimes referred to as metabolic encephalopathy when they affect brain function directly. These include dehydration, electrolyte abnormalities such as low sodium or potassium levels, kidney failure leading to toxin buildup, liver failure impairing detoxification processes, diabetic ketoacidosis (a serious complication of diabetes), and other endocrine disorders like thyroid dysfunction.
**3. Medications and toxins:**
Many medications commonly prescribed to older adults can induce or worsen delirium due to their effects on the central nervous system or through side effects that alter metabolism or electrolytes. Drugs with anticholinergic properties—such as certain antidepressants, antipsychotics (like quetiapine), antihistamines, benzodiazepines (sedatives), opioids for pain relief, diuretics causing electrolyte shifts—are notorious for triggering cognitive impairment in susceptible individuals.
Additionally, withdrawal from substances such as alcohol or sedatives can provoke acute confusion states resembling delirium.
Exposure to toxins including heavy metals like lead or mercury may also contribute but is less common in hospital settings.
**4. Central nervous system pathology:**
Acute neurological events such as strokes (acute vascular insults), traumatic brain injuries from falls or accidents during hospitalization (e.g., hip fractures), meningitis (infection of the protective membranes around the brain), seizures, tumors affecting cognition—all these conditions can directly disrupt normal brain activity resulting in delirious states.
**5. Cardiorespiratory problems:**
Conditions that reduce oxygen delivery to the brain play an important role too: anemia reduces blood’s oxygen-carrying capacity; pulmonary embolism blocks lung blood flow; chronic obstructive pulmonary disease causes carbon dioxide retention; heart failure impairs circulation—all these lead to hypoxia/hypercapnia which impairs neuronal function acutely.
Dehydration worsens blood volume and perfusion further contributing to cerebral dysfunction.
**6. Other precipitating factors related specifically to hospitalization environment:**
Hospital stays themselves introduce risks for developing delirium through multiple mechanisms:
– Major surgery stresses body systems profoundly while anesthesia drugs linger.
– Pain following injury/surgery increases stress hormones impacting cognition.
– Sleep deprivation caused by noise/light disruptions on wards interferes with normal circadian rhythms critical for mental clarity.
– Sensory impairments such as hearing loss or vision problems make orientation difficult.
– Physical restraints like Foley catheters increase discomfort and immobility.
– Frequent room changes disorient patients unfamiliar with new surroundings.
– Constipation and urinary retention cause discomfort plus metabolic disturbances worsening mental status.
Older adults have predisposing vulnerabilities making them more susceptible than younger people:
– Age-related decline reduces cognitive reserve—the ability of the brain to compensate under stress
– Pre-existing dementia significantly raises risk since baseline cognition is already impaired
– Sensory deficits limit environmental cues needed for orientation
– Polypharmacy increases chances of adverse drug interactions
Because many cases involve multiple overlapping causes simultaneously—such as infection plu
