Aging & Health A to Z
Causes & Symptoms
Healthcare professionals still don't completely understand what makes a person delirious, but many factors are probably involved, and some causes are now known. Generally, people who become delirious already have some type of illness, and are exposed to some additional injury or environmental trigger. For example, if a patient already has dementia, then a relatively minor injury or upset—such as a single dose of a new medication or a change in residence—may bring on delirium.
In fact, dementia is the most common risk factor for delirium, and two-thirds of cases of delirium occur in patients who already have dementia. In other patients who aren’t as vulnerable, delirium may develop only after several factors have occurred together, such as general anesthesia, major surgery, and psychiatric medications.
Addressing just one contributing factor is unlikely to resolve delirium in an older person; they should all be addressed when possible. A key goal for the healthcare professional is to find as many causes as he or she can identify and correct those that are reversible.
Reversible causes of delirium are outlined by the following acronym (DELIRIUM):
Drugs, including any new medications, increased dosages, drug interactions, over-the-counter drugs, alcohol, etc
Electrolyte disturbances, especially dehydration, and thyroid problems
Lack of drugs, such as when long-term sedatives (including alcohol and sleeping pills) are stopped, or when pain drugs are not being given adequately
Infection, commonly urinary or respiratory tract infection
Reduced sensory input, which happens when vision or hearing are poor
Intracranial (referring to processes within the skull) such as a brain infection, hemorrhage, stroke, or tumor (rare)
Urinary problems or intestinal problems, such as inability to urinate or constipation
Myocardial (heart) and lungs, eg heart attack, problems with heart rhythm (arrhythmia), worsening of heart failure or chronic obstructive lung disease.
Delirium can result from an imbalance in brain chemicals (neurotransmitters), crucial molecules that relay signals between nerves. A particularly important neurotransmitter is acetylcholine. One reason that people with dementia (such as Alzheimer’s disease) are at high risk of delirium is that the brain damage found in dementia kills the brain cells that produce acetylcholine. If oxygen or glucose levels in the brain decrease, even a little, the amount of acetylcholine drops even more dramatically. In such cases, the brain functions abnormally, producing delirium.
Other brain chemicals, such as dopamine, also contribute to delirium, because they regulate the amount of acetylcholine in the brain.
Side effects of familiar medications or sudden withdrawal from drugs are the most common and most treatable causes of delirium. Since many older people take multiple medications which may interact in harmful ways, you must be sure that the appropriate healthcare professionals are told about every prescription and non-prescription drug ibeing taken.
Alcohol abuse is frequently overlooked as a cause of delirium in older adults. Either overuse (intoxication) or a sudden withdrawal from alcohol can cause delirium. Delirium caused by withdrawal of alcohol appears to be as common in older adults with alcoholism as in their younger counterparts, although the death rate after withdrawal is higher in older alcoholics.
Virtually any physical illness or condition can bring on delirium, especially when more than one illness is present. Sometimes, delirium is also the first sign of a serious, life-threatening illness such as a heart attack. In hospital, the most common causes are sudden blood loss, dehydration, low blood pressure, fluid retention, infections, low levels of oxygen (hypoxia), kidney or liver failure, high blood sugar (hyperglycemia) or low blood sugar (hypoglycemia) in the blood, intestinal blockage (impaction), sleep deprivation, or inability to urinate. Delirium caused by a sudden change in the nervous system, such as a stroke, brain tumor, or brain infection, is less common. Immobility, sleep deprivation or fragmented sleep, and pain can all contribute to bringing on delirium.
Delirium can also result from too little stimulation of the senses, especially in people who already have some degree of mental impairment, or who are confined to a featureless hospital or nursing home room. In one study, delirium after an operation occurred twice as often in patients in intensive care units without windows as in patients in similar units with windows. In addition, a form of delirium that occurs in the evening (known as “sundowning”) may be partly due to sensory deprivation. Vision and hearing loss may also make it more difficult for the person to perceive reality and increases the likelihood of delusions or hallucinations.
Delirium after Surgery
Delirium may be the most common complication after surgery in older adults, and leads to longer hospital stays, a higher death rate, and a greater need for nursing-home care afterwards. It may also signal that there will be complications after surgery.
The chance that a patient will become delirious after an operation increases if a patient is an older adult, already has dementia or a physical disability, abuses alcohol, or has very abnormal blood tests. Also, certain types of operations are more frequently associated with delirium. For example, delirium is much more common after hip surgery and heart surgery.
Symptoms and Warning Signs
Delirium is recognized by the presence of a number of specific symptoms, but these may change quickly, for example, from lethargy to agitation and then back again. The symptoms also vary quite a bit from one person to the next. Delirium may also come and go within a 24-hour period and delirious patients often have lucid intervals during the course of a day.
Typical symptoms of delirium include:
- Sudden onset over hours to days
- Slurred speech and language difficulties: talking that doesn’t make sense
- Changes in feeling (sensation) and perception
- Easily distracted, decreased attention, concentration, and environmental awareness; usually more alert in the morning than at night; in and out of consciousness
- Changes in movement (for example, may be slow moving or very restless)
- Changes in sleep patterns, such as reversed sleep-wake cycles
- Confusion and disorientation: not aware of correct time or place
- Memory loss, including decreased short-term memory and recall
- Disorganized thinking
- Emotional or personality changes, with frequent changes in moods, including anger, agitation, anxiety, apathy, depression, fear, euphoria, irritability, suspicion
- Hallucinations (visual, but not auditory)
- Signs of medical illness (such as fever, chills, pain, etc) or drug side effects.
Updated: November 2014
Posted: March 2012