Visual Hallucinations in Long-Term Care: Page 2 of 4
Dementia- and Delirium-Related Hallucinations
Dementia is the most common cause of visual hallucinations in older adults,10 and they can occur with dementia of any etiology. The most common cause of dementia is Alzheimer’s disease, and approximately 18% of patients with Alzheimer’s disease experience visual hallucinations.11 Dementia-related hallucinations are typically non-threatening and may even be comforting. They often involve adults, children, or animals present in the room—the so-called “phantom boarder syndrome.”12 Although Lewy body dementia (LBD) is less common than Alzheimer’s dementia, nearly 80% of patients with LBD experience visual hallucinations, and these hallucinations usually occur much earlier in the course of the illness.13
Visual hallucinations are sometimes subtle, early symptoms of delirium.14 Delirium-related hallucinations can take any form and are perhaps better described as illusions: misperceptions of actual objects, such as falsely seeing a piece of furniture as a person or an animal. Patients whose delirium is identified early after onset have a better prognosis because early identification allows its underlying cause to be diagnosed and treated promptly. Patients with underlying dementia are at significantly greater risk of developing delirium.15,16 Common causes of delirium include infections (eg, urinary, respiratory, skin); metabolic disorders, such as dehydration, electrolyte imbalance, end-organ failure, hyperglycemia, hypoglycemia, and hypoxia; cardiovascular conditions, including arrhythmias, heart failure, myocardial infarction, and shock; neurologic disorders, such as head trauma, subdural hematoma, seizures, and stroke; an adverse reaction to drugs, including anticholinergics, sedatives, and opioids; and conditions such as urinary retention and fecal impaction.
Use of certain illegal and prescribed substances, intoxication, and substance withdrawal are well-known causes of visual hallucinations.17 Prescription and over-the-counter medications are common sources of visual hallucinations in older adults. The most frequent offenders are anticholinergic agents, many of which are available over the counter, and dopaminergic agents, such as levodopa and dopamine agonists. Other commonly used drugs known to induce hallucinations in susceptible individuals are corticosteroids, opioids, and antibiotics (including quinolones and carbapenems). Clinicians should also investigate the patient’s use of over-the-counter drugs, herbal preparations, and complementary medications; often, patients and families do not recognize the need to report the use of these agents. The risk of visual hallucinations and other adverse drug reactions corresponds positively to the number of medications taken. Given the high rate of polypharmacy among older adults, drug-drug reactions should be considered when evaluating patients for visual hallucinations.
Although the abuse of alcohol and of prescribed or illicit drugs are probably less common among today’s older adults in the community and in LTC than in younger populations, such abuses do occur, even in seemingly secure LTC facilities. Illicit drugs commonly associated with visual hallucinations include amphetamines, cocaine, hallucinogens (eg, lysergic acid diethylamide), phencyclidine, and cannabis. Hallucinations are also a fairly common idiosyncratic reaction to opioid drug use, whether prescribed or illicit.
With many drugs, withdrawal can produce hallucinations, especially when discontinuing alcohol, sedatives, hypnotics, and anxiolytics. Alcohol withdrawal commonly causes nocturnal visual hallucinations and may even produce hallucinations in patients with an otherwise clear sensorium. Clinicians should keep in mind that older adults often show attenuated autonomic reactivity and that these patients may not experience more typical reactions to alcohol withdrawal, such as tachycardia, hypertension, tremor, and diaphoresis.17
Hallucinations and Psychiatric Illness
Primary psychiatric conditions such as schizophrenia or mood disorders may produce hallucinations. Although auditory hallucinations are more common with these psychiatric conditions, patients who experience visual hallucinations indicate that they are often complex and bizarre.
Many bereaved individuals have visual hallucinations of a recently deceased loved one, particularly when the deceased was a spouse. Interviews with approximately 300 widowed men and women found that nearly half had hallucinations of their deceased spouse, with visual hallucinations slightly more common than auditory hallucinations.18 Surviving spouses who were older (aged ≥40 years) when the death occurred were more likely to have hallucinations than those who were younger, and some experienced the hallucinations for a decade or more.18 Hallucinations of the deceased are typically short and readily recognized as unreal, yet they can nevertheless be upsetting. Some individuals might be worried that they have a serious mental or neurologic illness, but these experiences are benign and are best thought of as a normal part of the bereavement process.
Visual and Neurological Causes
Among older adults considered psychologically and cognitively intact, CBS is a common and benign cause of visual hallucinations, yet it remains underrecognized.1,19,20 Most patients with CBS have central or ocular visual impairment, and it has been estimated that up to 60% of patients with severe visual loss experience one or more visual hallucinations.21 Although macular degeneration is the visual impairment most commonly associated with CBS, any condition that diminishes vision can cause the syndrome.1,2 Little to no correlation has been observed between the severity of visual impairment and the prevalence of CBS.1 Patients with CBS demonstrate no evidence of delirium, dementia, or functional psychiatric illness and generally retain their insight to varying degrees.1,4,22-24
CBS-related hallucinations are purely visual and typically described as vivid and complex.1,20 The most common subjects are people or animals. Our case patient, who had cataracts and saw cats and birds is a classic example of a CBS patient. The mechanism of CBS is uncertain, but most researchers think it is a deafferentation phenomenon analogous to phantom limb sensation.1,22,24,25
Various neurological conditions occasionally cause hallucinations, yet they are rarely reported as causes of visual hallucinations in the LTC setting. Patients who experience seizures and migraines occasionally experience visual hallucinations. Sufferers of occipital seizures (these are rare) and migraines usually report elemental (simple) hallucinations consisting of lines, patterns, or simple shapes. Patients having temporal lobe seizures may present with complex images or report unusual visual phenomena (eg, macropsia, micropsia, and autoscopy).26,27 Rarely, a stroke or other lesion in the midbrain (ie, in the region of the cerebral peduncles) can produce so-called “peduncular hallucinosis,” which usually takes the form of people or animals.28