Yes, many people with dementia do see things that aren’t there. These are called visual hallucinations, and they’re one of the more common and distressing symptoms of certain types of dementia. How often they happen, how vivid they are, and what triggers them depends largely on the type of dementia, how far it has progressed, and whether other medical issues are involved.
If you’re noticing this in someone you care for, it helps to understand what’s happening in their brain, which types of dementia are most likely to cause it, and what you can actually do about it.
Hallucinations, Illusions, and Delusions Are Different
Before anything else, it’s worth sorting out three experiences that often get lumped together. With a hallucination, no object is actually present, but the person’s brain tells them they’re seeing children in the living room, people at the window, or animals on the floor. These visions feel completely real to the person experiencing them.
An illusion is different. Something is physically there, but the person misidentifies it. A coat rack becomes a person standing in the corner. A pattern on the carpet looks like insects. The brain is misinterpreting real visual input rather than generating something from nothing.
Delusions are something else entirely: fixed false beliefs that can’t be reasoned away. A common example is Capgras syndrome, where a person with dementia becomes convinced that a spouse or close family member has been replaced by an imposter. Another is accusing someone of stealing a misplaced item. Delusions don’t involve seeing things, they involve believing things that aren’t true.
All three can occur in dementia, sometimes overlapping. But visual hallucinations are the type most people are asking about, and they vary dramatically depending on the diagnosis.
Which Types of Dementia Cause Hallucinations
Not all dementias are equally likely to produce visual hallucinations. The differences are significant enough that hallucinations themselves can be a diagnostic clue.
Lewy Body Dementia
Visual hallucinations are a core feature of dementia with Lewy bodies (DLB), occurring in 32 to 85 percent of autopsy-confirmed cases. They tend to appear early in the disease, often before major memory loss is obvious. This is one of the key features that distinguishes Lewy body dementia from Alzheimer’s. The hallucinations are typically vivid and detailed: people, animals, or sometimes complex scenes. Patients may describe seeing a group of children playing or a stranger sitting in a chair. Early visual hallucinations strongly increase the odds that a person has Lewy body dementia rather than Alzheimer’s.
Parkinson’s Disease Dementia
Parkinson’s disease and Lewy body dementia share underlying biology, and hallucinations are common in both. Up to 45 percent of people with Parkinson’s who don’t have dementia experience visual hallucinations. That number climbs to roughly 65 percent in those who develop Parkinson’s disease dementia. The hallucinations often start as minor visual disturbances, like seeing movement at the edge of their vision or briefly misidentifying a shadow, before becoming more formed and frequent.
Alzheimer’s Disease
Hallucinations in Alzheimer’s are less common than most people assume. Across existing research, the average reported prevalence is about 13 percent, but a large study of over 1,200 patients, most in early stages, found that only 4.5 percent experienced hallucinations. That rate is similar to what you’d find in older adults without dementia. Hallucinations in Alzheimer’s tend to appear in moderate to advanced stages, not early on. When a person in the early stages of what’s thought to be Alzheimer’s starts seeing things, clinicians are trained to reconsider the diagnosis and look for other possibilities like Lewy body dementia, delirium, or vision problems.
What’s Happening in the Brain
Visual hallucinations in dementia aren’t random glitches. They reflect specific changes in brain chemistry and structure. In both Alzheimer’s and Lewy body dementia, there’s strong evidence of reduced activity in the brain’s chemical signaling system that uses acetylcholine, a neurotransmitter involved in attention, perception, and memory. Lower acetylcholine function is consistently linked to more frequent hallucinations.
Postmortem brain studies reveal something interesting: these changes appear to be functional rather than structural. The neurons and connections are still largely intact, but the chemical environment has shifted. That’s part of why medications that boost acetylcholine activity can sometimes reduce hallucinations.
In Lewy body and Parkinson’s dementias, abnormal protein deposits accumulate in brain regions responsible for visual processing, emotional interpretation, and memory. These include areas involved in recognizing faces, processing what you see, and distinguishing real perceptions from internally generated ones. When these regions malfunction, the brain essentially fills in visual information that isn’t coming from the eyes.
Sudden Hallucinations Can Signal a Medical Emergency
If someone with dementia suddenly starts hallucinating when they haven’t before, or their hallucinations dramatically worsen over hours or days, the cause may not be the dementia itself. Delirium, a sudden state of confusion and altered awareness, is a common culprit, and it’s treatable.
The most frequent trigger for delirium in older adults is infection, accounting for nearly 50 percent of cases. Urinary tract infections are especially notorious because they present atypically in elderly people. Instead of the burning and urgency younger adults experience, older people with UTIs may show sudden confusion, drowsiness, agitation, falls, or hallucinations, often without fever.
Dehydration, electrolyte imbalances, and medication side effects are other common precipitating factors. This matters because delirium is reversible when the underlying cause is identified and treated. New or worsening hallucinations in someone with dementia should prompt a medical evaluation rather than being dismissed as “just the dementia getting worse.”
Vision Loss Can Also Cause Hallucinations
There’s another cause of visual hallucinations that’s frequently overlooked: poor eyesight. Charles Bonnet syndrome occurs in people with significant vision loss, such as from macular degeneration or glaucoma, whose brains generate visual images to compensate for reduced input. These hallucinations can be vivid and complex, including faces, animals, or geometric patterns.
The hallmark of Charles Bonnet syndrome is that the person knows the visions aren’t real. They maintain full insight, their thinking is otherwise normal, and they don’t experience hallucinations in other senses like hearing or touch. This is the critical distinction from dementia-related hallucinations, where insight tends to erode as the disease progresses. Because many older adults have both vision loss and early cognitive changes, the two conditions can be confused. Ensuring that someone has an up-to-date eye exam and proper corrective lenses can sometimes reduce or eliminate hallucinations that were never caused by dementia at all.
Environmental Triggers That Make It Worse
The physical environment plays a surprisingly large role. Poor lighting creates shadows that a person with dementia may misinterpret as people or animals. Reflections on shiny floors or furniture can look like water or movement. Mirrors are a particularly common trigger because the person may not recognize their own reflection and believe a stranger is in the room.
Some practical changes that help:
- Lighting: Keep rooms well lit, especially in the evening and at night, to reduce shadows and dark corners.
- Mirrors: Cover them with a cloth or remove them entirely if the person reacts to their reflection with fear or confusion.
- Background noise: Turn off televisions or radios that aren’t being actively watched or listened to. Sounds from another room can be misinterpreted as voices or intruders.
- Visual clutter: Busy patterns on wallpaper, carpets, or upholstery can trigger illusions. Simpler, solid-colored surfaces are easier for a compromised visual system to process.
How to Respond When It Happens
Your instinct may be to correct the person and explain that nothing is there. This rarely helps and often makes things worse. A person experiencing a hallucination isn’t making a mistake they can be talked out of. Their brain is generating a perception that feels as real as anything you’re seeing right now.
Validation-based approaches work better. That means accepting the person’s emotional reality without reinforcing the hallucination’s content. Use a calm, non-threatening tone. Maintain eye contact. If the hallucination is causing distress, acknowledge their feelings (“I can see that’s upsetting”) and gently redirect their attention to something else: a favorite song, a snack, a walk to another room, a photo album. The goal is to shift their focus without making them feel dismissed or patronized.
Not all hallucinations are distressing. Some people with Lewy body dementia see children playing or a cat sitting on the bed and aren’t bothered at all. In those cases, there may be no need to intervene. The hallucination only becomes a problem when it causes fear, agitation, or dangerous behavior.
Why Treatment Options Are Limited
Treating dementia-related hallucinations with medication is complicated. The drugs most commonly associated with reducing psychotic symptoms, antipsychotics, carry serious risks in people with dementia. The FDA placed a black box warning on these medications after 17 controlled studies showed that elderly dementia patients taking them were 1.6 to 1.7 times more likely to die than those given a placebo. Deaths were linked to heart failure, sudden cardiac events, and infections like pneumonia. These drugs are not approved for treating behavioral symptoms in dementia patients.
The risk is especially severe in Lewy body dementia, where people can have life-threatening sensitivity to antipsychotics. Medications that boost acetylcholine activity, which are already used to treat cognitive symptoms in some dementias, can sometimes reduce hallucination frequency as a secondary benefit. But there is no medication that reliably eliminates hallucinations in dementia without significant trade-offs.
That’s why non-drug strategies, adjusting the environment, managing medical triggers, treating vision problems, and responding with validation, remain the first and often the most effective line of defense.