The Dominance of Dementia
Among older adults, the most common reason for psychosis is a neurocognitive disorder, with dementia being the leading culprit. As the brain's cognitive function declines, it can lead to distorted perceptions of reality. Psychosis often develops in the middle stages of dementia and is a significant source of caregiver burden and increased morbidity. The specific type of dementia can influence the presentation of psychotic symptoms.
Alzheimer's Disease
Psychosis affects a substantial percentage of people with Alzheimer's disease (AD), with one study reporting a prevalence of around 41%. The most frequent psychotic symptoms are delusions, often simple and paranoid in nature, such as believing belongings are being stolen or a spouse is unfaithful. Visual hallucinations can also occur, though typically less often than delusions.
Dementia with Lewy Bodies (DLB)
Compared to other forms of dementia, psychosis is particularly prevalent in DLB, with one study finding that visual hallucinations can affect up to 78% of patients. These hallucinations are often vivid, detailed, and recurring, sometimes involving small people or animals. Visual hallucinations in DLB are considered a core diagnostic feature.
Distinguishing Delirium from Other Psychotic Causes
It is critically important to differentiate psychosis from delirium, as the causes and treatment are vastly different. Delirium is an acute confusional state with a fluctuating course, and it is a very common cause of psychosis-like symptoms in seniors. Unlike dementia, which has a gradual onset, delirium starts suddenly over a few hours or days. The most common causes of delirium in the elderly are infections (like urinary tract infections), medication side effects or withdrawal, severe pain, and dehydration. Addressing the underlying medical issue can often resolve the delirium and associated psychotic symptoms.
Medications and Other Medical Conditions
Older adults are more susceptible to medication side effects that can trigger psychosis due to age-related changes in drug metabolism and clearance. This risk is amplified by polypharmacy, where patients take multiple medications simultaneously. Numerous classes of drugs can induce psychotic symptoms, including:
- Antiparkinsonian drugs: Used to manage Parkinson's disease, these can cause vivid hallucinations.
- Anticholinergics: Often found in over-the-counter sleep aids and some allergy medications, these can cause confusion and hallucinations.
- Steroids: Corticosteroids can have neuropsychiatric side effects, including psychosis.
- Cardiovascular medications: Some antiarrhythmics and blood pressure medications have been linked to psychosis.
Besides medications, various other medical conditions can also lead to secondary psychosis in seniors, such as stroke, epilepsy, brain tumors, metabolic imbalances, and electrolyte disturbances. A thorough medical workup is essential to investigate these potential causes.
Primary Psychiatric Disorders in Late Life
While less common for new-onset cases than dementia or delirium, primary psychiatric disorders can also cause psychosis in the elderly. A distinguishing factor is that primary psychotic symptoms are the core feature of the illness, not a secondary symptom of a medical or neurological condition.
- Psychotic Depression: The most common primary psychiatric cause of late-life psychosis, often involving delusions of poverty, guilt, or nihilism that are mood-congruent.
- Late-Onset Schizophrenia: A rare but distinct diagnosis, where symptoms first appear after the age of 40. Patients often have better premorbid functioning than those with early-onset schizophrenia.
- Delusional Disorder: Characterized by persistent, non-bizarre delusions without other features of psychosis, and typically affects functioning less severely than schizophrenia.
Comparing Causes of Psychosis in the Elderly
| Feature | Dementia-Related Psychosis | Delirium | Medication-Induced Psychosis |
|---|---|---|---|
| Onset | Gradual, worsening over months or years, often in middle stages of the disease | Acute, sudden onset over hours or days | Subacute, often within days of starting, changing, or stopping a medication |
| Course | Progressive, may fluctuate but generally persistent | Fluctuating, often worse at night (sundowning) | Resolves with the cessation of the offending medication |
| Level of Consciousness | Alert, but with underlying cognitive impairment | Altered, inattentive, and disorganized thinking | Typically alert, but with disorganized thoughts and behavior |
| Hallucinations | Primarily visual, especially in Lewy Body Dementia | Predominantly visual, but can be multisensory | Can be visual, tactile, or auditory |
The Critical Role of Accurate Diagnosis
An accurate diagnosis is paramount for effective management. For new-onset psychosis in an older adult, a healthcare professional must perform a thorough evaluation. This process involves a detailed review of medical history, a physical exam, and laboratory tests to rule out reversible causes like delirium, infections, or medication side effects. The initial treatment strategy involves addressing any reversible underlying causes before considering long-term pharmacological interventions.
Treatment Considerations
Once the cause is identified, the treatment approach can be tailored. For medication-induced psychosis, the solution may be as simple as adjusting or discontinuing the offending drug. In cases of delirium, treating the root infection or imbalance is the priority. For dementia-related psychosis, non-pharmacological interventions are the first line of defense, including environmental adjustments and behavioral strategies. When pharmacological treatment is necessary, antipsychotic medications are used cautiously at low doses, given the increased risk of adverse effects and mortality in the elderly, particularly those with dementia. More information on psychosis can be found from the National Institute of Mental Health (NIMH).
Conclusion
While the most common cause of psychosis in the elderly is dementia, it is essential to consider the full spectrum of potential causes. The diagnostic process must be comprehensive, ruling out reversible causes like delirium and medication side effects before confirming a dementia-related or primary psychiatric illness. For families and caregivers, recognizing the signs and symptoms and seeking professional evaluation is the first and most critical step toward finding effective and safe treatment.
