Writer: Milly Mak
Editor: Mia McDonald Rose
Artist: Sam Patel
One morning, a daughter finds her mum talking to someone in an empty kitchen, saying that she’s taking register of all the children in the room. Despite her daughter’s reassurance that the children don’t exist, she’s convinced she can see them. She has Lewy body dementia, and it is causing hallucinations.
Introduction: The Neglected Half of Dementia
In an aging population, dementia is becoming increasingly common, with over 55 million people worldwide living with dementia today. Dementia is described as cognitive decline caused by a neurodegenerative disease. You may be familiar with the cognitive symptoms associated with dementia, such as memory loss and disorientation. These symptoms are disabling on their own, but many people forget that the same neurodegenerative disease can also impact psychiatric function, which can include hallucinations, delusions, apathy, and even social inappropriateness. These disproportionately affect some dementias more – psychiatric symptoms are embedded in the diagnostic criteria for dementia with Lewy bodies and frontotemporal dementia. However, 97% of elderly with dementia develop at least one psychiatric symptom within 5 years of diagnosis. For patients and their carers, they are often even more difficult to cope with than cognitive impairments, as they can impact relationships and motivation. Among the many behavioral and psychiatric changes, psychotic symptoms are a clear window into how dementia reshapes perception and identity.
Hallucinations and Delusions: A Vivid Manifestation of Dementia
While psychiatric symptoms in dementia range from apathy to agitation, psychotic symptoms like hallucinations and delusions are some of the most devastating ways dementia can impact the mind. Psychotic symptoms, which are perceptual and thought content disturbances often associated with schizophrenia in psychiatry, are common in dementia with Lewy bodies (DLB) and can sometimes occur in Alzheimer’s disease and frontotemporal dementia. Delusions and hallucinations in dementia have patterns that are distinct from schizophrenia. DLB patients often get suspicious, such as suspecting a spouse is cheating or someone is stealing from them. They also sometimes experience the Capgras delusion, where they believe someone has replaced their spouse or relative. As for hallucinations, they experience animate visual hallucinations – seeing humans or creatures when they’re not there – more often than auditory “voice” hallucinations.
Why do these symptoms occur? A meta-analysis identified that degeneration of the fronto-temporal areas of the brain – which assimilates information – are associated with the formation and maintenance of delusional beliefs, while the frontal occipital area – responsible for sensory processing and predictive coding – is linked to hallucinations. This might show that in these forms of dementia, neurodegeneration impedes the ability to process the sensory world normally, causing them to misperceive or “guess” items in their field of sight. Along with impaired information reasoning, the brain might produce false visual images or ideas in an attempt to understand the environment.
Although it may be frustrating for carers, family, and friends, these delusions and hallucinations are reality to patients. It is not helpful to convince them otherwise; instead, reassuring and distracting them may be more comforting.
Conclusion
There are still many limitations to our understanding of this topic due to limitations in research tools and insufficient clinical screening. Attempts to treat these symptoms with psychosocial therapies as well as pharmacological treatments have been made, but without much success. In addition to psychiatric symptoms, behaviour and mood changes can also arise from the distress of the condition itself, due to reduced independence, inability to participate in social activities, or breakdown of relationships. It is important to raise awareness of these symptoms to better support patient quality of life, to predict worse outcomes and disease progression, and to develop treatments.
We often think of dementia as a story of forgetting. But hallucinations, delusions, and mood changes remind us that dementia also transforms the emotional and perceptual worlds people live in. Recognising these symptoms is essential for understanding the lived experiences of dementia.
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