The Prevalence, Impact, and Proposed Neurobiology of Delusions and Hallucinations Associated With Dementia-Related Psychosis

Dr. Stahl: Hello, my name is Dr. Stephen M. Stahl and I am an adjunct professor of psychiatry at the University of California, San Diego, an honorary visiting senior fellow at the University of Cambridge, and director of psychopharmacology for the California Department of State Hospitals.

Dr. Brunton: And I’m Dr. Stephen Brunton, executive vice president for the Primary Care Education Consortium and associate adjunct clinical professor in the department of family medicine at Touro University in Vallejo, California. In this video, we will discuss the prevalence, impact, and proposed neurobiology of delusions and hallucinations associated with dementia-related psychosis.

Dr. Stahl: Delusions and hallucinations are prevalent across the dementias, as shown here.1-15 Although the rates of delusions and hallucinations vary, they occur in each of the 5 most common dementia types.1-15 Delusions and hallucinations are most common in patients with dementia with Lewy bodies, or DLB, and least common in patients with frontotemporal dementia.1-15 Overall, approximately 2.4 million people in the US have dementia-related psychosis, meaning that they experience delusions and hallucinations.1-15

Before we explore the impact delusions and hallucinations can impose on patients, let’s take a moment to understand what delusions and hallucinations are and how they manifest in patients with dementia.

Dr. Stahl: Delusions can be defined as false, fixed beliefs that are not amenable to change in light of conflicting evidence.16 There are several common types of delusions in patients with dementia, including delusions of reference, which is an individual’s belief that a neutral event has a special meaning for them, delusions relating to theft or possessions being hidden, and delusions relating to the presence of strangers in the house.9

Dr. Stahl: Delusions are distinct from hallucinations, which are perception-like experiences that occur without an external stimulus and are sensory, meaning that they involve 1 or more of the 5 senses. Patients may see, hear, taste, smell, or feel something that is not there.16 Some patients may realize they are hallucinating, but others may not be able to distinguish their hallucinations from reality.17

Now that we’ve become familiar with the prevalence of delusions and hallucinations in patients with dementia-related psychosis, and the key defining features of delusions and hallucinations, let’s explore the impact of delusions and hallucinations in patients with dementia.

Dr. Stahl: To determine whether the presence of delusions and hallucinations affected clinical outcomes for people with Alzheimer’s disease, Scarmeas and colleagues conducted a study that followed 456 individuals with early Alzheimer’s disease for up to 14 years. Cognitive and functional outcomes were assessed in addition to rates of institutionalization and death. Cognition was assessed with the Columbia Mini-Mental State Examination, or MMSE, and function was assessed with the Blessed Dementia Rating Scale, or BDRS. Delusions were noted for 34% of subjects at baseline and for 70% of subjects at any subsequent evaluation. Hallucinations were present in 7% of subjects at the initial visit and in 33% of subjects at any subsequent visit. In this study, the term “any delusions” or “any hallucinations” includes both transient and persistent delusions or hallucinations.

Statistical modeling of the study data, adjusted for the factors indicated in the footnote below this graph, showed that the presence of delusions and hallucinations was associated with a significantly increased risk of cognitive and functional decline, indicated in the graph as a risk ratio greater than 1. In this study, the presence of hallucinations, but not delusions, was associated with a significantly increased risk of institutionalization and death. These data suggest the presence of delusions and hallucinations may increase the risk of worse outcomes in patients with Alzheimer’s disease.18

Dr. Brunton: Now that we’ve become familiar with delusions and hallucinations in patients with dementia, let’s take a moment to discuss the basic pathological features of dementia, and how damage to certain regions of the brain can be implicated in delusions and hallucinations in the 5 most common dementias.

In most dementia types, pathological findings indicate neuronal loss and/or dysfunction in association with the accumulation of protein deposits in the brain. These protein deposits can be referred to as plaques, fibrils, tangles, or Lewy bodies depending on their composition.19-23

Dr. Brunton: The pathology of vascular dementia is distinct from that of other dementia types. In vascular dementia, neuronal loss and/or dysfunction is thought to be caused by impaired cerebral blood flow.24

Dr. Brunton: Structural and functional neuroimaging implicates certain regions of the cortex in delusions and hallucinations across the dementias.25-28 The cortex is the outer layer of the cerebrum and integrates neural functions including cognition and sensory processing.29

Dr. Brunton: The cortex can be divided into 4 distinct lobes, each of which governs different functional domains.29 The frontal lobe is involved in motor function and higher-level cognition while the temporal lobe regulates memory as well as olfactory and auditory processing. The parietal lobe governs the processing of tactile sensory information, and the occipital lobe plays a role in interpreting visual stimuli.29

Dr. Brunton: Damage to the frontal and temporal regions of the cortex has been implicated in delusions and hallucinations across dementia types.25-28

Dr. Brunton: In Parkinson’s disease dementia and dementia with Lewy bodies, damage and/or dysregulation in the occipital region has also been associated with delusions and hallucinations.30,31

Dr. Stahl: In summary, approximately 2.4 million people in the US have dementia-related psychosis.32 The data collected by Scarmeas and colleagues suggest that the presence of hallucinations, but not delusions, may be associated with a significantly increased risk of institutionalization and death.18

Dr. Brunton: These data also suggest that the presence of delusions and hallucinations may be associated with a significantly increased risk of cognitive and functional decline.18 The pathology of dementia involves neuronal loss and/or dysfunction.19-23 Certain regions of the cortex are implicated in delusions and hallucinations across dementia types.25-31

We hope that the information presented in this video has been educational. Please watch the other videos in this series, and thank you for watching!

References

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Faculty

Touro University
Vallejo, CA
University of California, San Diego
La Jolla, CA