Psychosis in older adults is common and can be difficult to treat. Older adults have a 23% lifetime risk of psychotic symptoms (Reinhardt M and Cohen C, Curr Psychiatry Rep 2015;17(2):1), which can include any of the following:

• Delusions
• Disorganized thinking or behaviors
• Hallucinations
• Negative symptoms

This article reviews the most common causes of psychosis in older adults. For a quick guide, refer to: ­www.­thecarlatreport.com/LateLifePsychosisCauses 

Medical conditions, medications, and substance use

The first step is to rule out delirium, which we reviewed in the CGPR Jul/Aug/Sep 2022 article “Assessing and Treating Delirium in Older Adults.” Looking for medication or medical causes for psychosis is helpful, even if overt delirium is not present. Review the patient’s medication list and OTC meds with the Beers criteria in mind, and maintain a healthy suspicion of:

• Antiarrhythmic drugs
• Anticholinergics
• Anticonvulsants
• Antihistamines
• Benzodiazepines
• Steroids
• Stimulants

Also be wary of anti-parkinsonian drugs and dopaminergic medications (eg, ropinirole, pramipexole), which can evoke visual hallucinations (VH) in some ­patients.

Next, consider additional lab work. Depending on the clinical context, you will want to screen for thyroid disease, diabetes, B12 deficiency, hyponatremia, and dehydration (Tampi R et al, Ther Adv Psychopharmacol 2019;9:1–13). Also check a urine toxicology screen to assess for substance use, which can cause psychosis from both intoxication (eg, alcohol, cannabis, PCP/hallucinogens, inhalants) and withdrawal (eg, alcohol, sedative-hypnotics). In this age group, alcohol use and prescription medication use are most common. See CGPR Apr/May/Jun 2023 for more information.

Lastly, severe and chronic untreated sleep disorders can cause psychosis, as can brain lesions or seizure disorders. 

Dementia and psychosis 

After ruling out delirium and medical/medication causes, the next step is to evaluate for underlying dementia. It is well established that patients with Parkinson’s disease dementia (PDD) and Lewy body dementia (LBD) can develop psychotic symptoms at the same time as motor and cognitive symptoms. However, growing evidence shows that late-life psychosis can present prior to cognitive decline in other types of dementia as well, such as in the prodromal stages of Alzheimer’s disease (AD) (Ismail Z et al, Nat Rev Neurol 2022;18(3):131–144). 

Regardless of timing, most patients with dementia will eventually develop psychotic symptoms. Psychosis often develops in the middle stages of AD, with delusions of theft, infidelity, abandonment, and persecution being particularly common (Reinhardt and Cohen, 2015). As cognitive impairment worsens, patients may have misidentifications, such as thinking that images on the TV are real or that loved ones have been replaced by impostors. For these patients, it is helpful to distinguish between delusions (eg, persistent non-reality-based beliefs) versus general forgetfulness or confabulation (eg, inconsistent statements) (Ismail et al, 2022). 

If patients with dementia develop hallucinations, they are more likely to be non-frightening VH, as opposed to distressing auditory hallucinations (AH). Although VH are strongly identified with PDD and LBD, they can occur in any type of dementia, particularly in later stages. Regardless of the underlying cause of dementia, late-life psychosis is associated with greater cognitive impairment, increased caregiver distress, higher rates of morbidity and mortality, and institutionalization (Reinhardt and Cohen, 2015).  

Psychosis due to mood disorders

Delusions are the most common psychotic symptom in depressed older adults. These mood-congruent delusions often involve poverty, nihilism, somatization, guilt, or criminal activity (Reinhardt and Cohen, 2015). Associated symptoms include anxiety, agitation, poor appetite, self-neglect, and insomnia. Note that true AH are rare in this population, although patients often report negative ruminative thoughts. 

Mania in older adults can be dramatic and resemble delirium due to overtly disordered thinking. These patients tend to decompensate over weeks, differing from the slower onset in dementia (months) and the rapid onset in delirium (days). Psychosis due to mania can also develop for the first time in late life. When this occurs, it is more often secondary mania due to a medical or neurological cause. See CGPR Jan/Feb/Mar 2023 for more details. 

Primary psychotic disorders

Most older adults with schizophrenia were diagnosed decades earlier. The term late-onset schizophrenia (LOS) refers to the small subset of patients who develop symptoms between the ages of 40 and 60. They often present with paranoid delusions and AH (eg, accusations or comments on their behaviors), as well as less prominent negative symptoms. Although schizophrenia in general is associated with mild to moderate cognitive deficits, rapid forgetting and short-term memory loss are much more common with dementia (Iglewicz A et al, Psychiatr Clin North Am 2011;34(2):295–318).

Very-late-onset schizophrenia-like psychosis (VLOSLP) occurs in patients age 60 and over. Unlike other types of schizophrenia, VLOSLP may be a neurodegenerative disease, given its associated progressive cognitive deterioration and structural brain abnormalities (Tampi et al, 2019). Note that women are overrepresented in both LOS and VLOSLP. These patients are more likely to endorse various hallucinations. They also have a weaker family history of psychosis compared to patients diagnosed with schizophrenia when younger (Iglewicz et al, 2011).

Delusional disorders account for up to 4% of inpatient psychiatric hospitalizations and often appear in middle age. They are more common in poorer and immigrant populations, and slightly more common in women (Iglewicz et al, 2011). Risk factors include a family history of schizoid/avoidant/paranoid personality disorder or a primary psychotic disorder. Hearing and vision loss may also play a role in developing delusional disorders (Reinhardt and Cohen, 2015). Patients typically experience social impairments but have normal cognitive and occupational functioning (Tampi et al, 2019). 

Your patient’s lab work is unremarkable, and a medication review is unrevealing. You notice word-finding difficulties and episodic memory loss during the interview, and the patient scores 17/30 on the Montreal Cognitive Assessment. After obtaining collateral information from her daughter documenting that the cognitive difficulties have been progressing gradually over years, you diagnose the patient with major neurocognitive disorder due to Alzheimer’s disease with a behavioral disturbance (psychosis). 

CARLAT VERDICT

Consider the following causes for late-life psychosis: delirium, dementia, medical illness, medications, substance use, mood disorders, schizophrenia, and delusional disorders.