Most people picture dementia as memory loss: a name that will not come, a kettle left boiling, the same question asked three times in an afternoon. That picture is so firmly fixed in Irish life that it has become the test everything else is measured against, and when someone’s symptoms do not match it, the search for an answer can take years.
There is a second common form of dementia that behaves very differently. It can begin with vivid visual hallucinations in someone whose memory is largely intact. It can begin with a partner being kicked or punched in the night, because the person beside them is physically acting out a dream. It can begin with a good day followed by a day of blankness so complete that the family wonders whether they imagined the good one. It is called Lewy body dementia, roughly 10,000 people in Ireland are thought to be living with it, and fewer than one in twenty of them has been told that is what they have.
TL;DR
- Lewy body dementia (LBD) accounts for around 20% of the nearly 65,000 people living with dementia in Ireland, about 10,000 people, yet fewer than 5% receive a formal diagnosis, according to the Global Brain Health Institute at Trinity College Dublin.
- The four core features are fluctuating alertness, detailed recurrent visual hallucinations, acting out dreams during sleep (REM sleep behaviour disorder), and Parkinson’s-type stiffness or slowness. Memory loss is often not the first sign.
- Standard antipsychotic medicines can be dangerous here. Severe sensitivity reactions occur in an estimated 30% to 50% of people with LBD and carry roughly double the mortality risk, so the diagnosis needs to be on the chart before anyone reaches for them.
- Cholinesterase inhibitors such as rivastigmine and donepezil tend to work better in LBD than in Alzheimer’s disease, particularly for hallucinations, so an accurate diagnosis changes treatment as well as expectations.
- Irish routes to assessment are the GP, a Memory Assessment and Support Service and a Regional Specialist Memory Clinic. Only four of the five recommended regional clinics are open, and of ten priority areas earmarked for a new memory service, three are running. Supports include the Alzheimer Society of Ireland helpline on 1800 341 341 and Lewy Body Ireland.
Ten thousand people, fewer than five hundred diagnoses
The figures come from the research team at Trinity College Dublin and the Global Brain Health Institute who were awarded just under €2.5 million by the Health Research Board in 2024 for EMERALD-Lewy, the first large-scale programme of Lewy body research in Ireland. Their starting position was blunt: LBD makes up about a fifth of dementia in Ireland, which puts it at roughly 10,000 people, and fewer than 5% of them have a formal diagnosis. Do the arithmetic and the number of people in this country who have been correctly named is in the hundreds.
Professor Iracema Leroi, who leads the programme and runs a clinic at St James’s Hospital for people whose Parkinson’s-related conditions have reached the dementia stage, called the funding a chance to “finally move the agenda forward” for those 10,000 people. Ken Greaney, who co-founded the advocacy group Lewy Body Ireland, put it more plainly when the grant was announced: it took seven years for his father Dave to be given the diagnosis. Seven years is not an outlier. A delay of two or three, with a wrong label in between, is closer to the norm.
The four signs that are not memory loss
International diagnostic criteria, updated in 2017 by the Lewy body consortium, set out four core clinical features. A clinician can reach a diagnosis of probable LBD with two of them, or with one plus a supporting scan.
Fluctuating cognition. Not the ordinary variation of a good day and a tired day, but pronounced swings in attention and alertness. Someone can be conversational and sharp at lunchtime and, by teatime, staring past you, unreachable, for an hour. Families often describe it as the lights going on and off. Because the good spells are genuinely good, they can be mistaken for proof that nothing is wrong.
Recurrent visual hallucinations. These are typically detailed and well formed rather than vague: children in the hall, a cat on the chair, people at the end of the bed. They may or may not be frightening. Crucially, they appear in someone whose memory may still be working reasonably well, which is why the first referral is so often to psychiatry rather than to a memory service.
REM sleep behaviour disorder. In healthy sleep the body is paralysed during dreaming. In this disorder that paralysis fails and the dream is acted out: shouting, kicking, punching, falling out of bed. It is usually the bed partner who notices, and it can arrive years or even decades before any change in thinking. In an international study of 1,280 people with this sleep disorder and nothing else, around 6% a year went on to develop a related condition, and roughly three-quarters had done so within twelve years. That is not a reason to panic after one bad night. It is a strong reason to mention it to a GP rather than quietly moving into the spare room.
Parkinsonism. Slowness, stiffness, a shuffle or reduced arm swing, sometimes a tremor at rest. In LBD this usually appears alongside or after the cognitive changes, which is what distinguishes it from Parkinson’s disease, where movement symptoms come first by a long margin.
Supporting features matter too, and they are the ones most likely to be filed as unrelated: repeated falls and faints, severe constipation, loss of smell, low blood pressure on standing, depression, and daytime sleepiness out of proportion to the night’s rest.
Why it gets called something else first
Researchers at Trinity’s Centre for Health Policy and Management interviewed 23 people living with mild to moderate dementia in Ireland, 12 with LBD and 11 with Alzheimer’s disease, and published what they found in Social Science and Medicine. The two groups described different countries. Participants with Alzheimer’s generally found a diagnostic pathway that existed and worked, because their symptoms matched the cultural script. Participants with LBD met structural barriers: complex symptoms, limited specialist knowledge, and geographic inequality in reaching the services that could assess them, which bore hardest on rural participants. After diagnosis they hit a second wall, with far less appropriate support available.
The researchers named the underlying problem precisely: the cultural dominance of the Alzheimer’s narrative. If the only dementia the public and much of the health service recognises is the one that starts with forgetting, then hallucinations get read as psychosis, dream enactment gets read as a sleep nuisance, and stiffness gets read as arthritis or ageing.
That gap extends into the places where many people with LBD eventually live. A 2026 survey by Trinity’s School of Medicine of 181 staff across all grades in long-term care facilities in the Republic found that 8.7% had never heard of Lewy body dementia, and that awareness of its critical features, including antipsychotic sensitivity, was limited across the board. More than three-quarters said they wanted training in it.
The medicine that can do real harm
This is the part worth knowing even if you never think about LBD again.
People with Lewy body dementia can have severe reactions to antipsychotic medicines, the class often reached for when an older adult in hospital or in a care setting becomes agitated or starts hallucinating. Estimates of severe neuroleptic sensitivity in LBD run from 30% to 50%. The reaction can come on suddenly: heavy sedation, rigidity, immobility, fever and confusion, in a picture that resembles neuroleptic malignant syndrome. Severe reactions have been associated with roughly a doubling of mortality.
Older medicines such as haloperidol are the clearest concern, but sensitivity has been reported with newer ones too. They should be a last resort, started low, and only after the diagnosis is known and other causes excluded.
Two practical consequences. First, if LBD is suspected or confirmed, it belongs on every list and letter: the GP record, the hospital chart, the nursing home file, the card in the wallet. An emergency department at two in the morning will not infer it. Second, ask about alternatives. The cholinergic loss in LBD is deeper than in Alzheimer’s, and cholinesterase inhibitors such as rivastigmine and donepezil are recommended first-line precisely because they tend to help here, including with hallucinations. In the main rivastigmine trial, 63% of those treated showed meaningful cognitive improvement compared with 30% on placebo, and they were less anxious and hallucinated less.
Seeing things is not always dementia
Before anyone starts building a case, two alternatives. Confusion or hallucinations that develop over hours or days, rather than months, are far more likely to be delirium, a medical emergency with a treatable cause such as infection, dehydration or a new medicine. And detailed hallucinations in someone with significant sight loss, who knows perfectly well that what they are seeing is not real, usually indicate Charles Bonnet syndrome, which is not a dementia at all. Insight is the giveaway: Charles Bonnet rarely removes it, LBD often does.
Getting assessed in Ireland
Start with the GP, and go armed. Write down the fluctuations with rough times and dates, note the hallucinations in detail, and above all report the sleep behaviour, because the bed partner is the only one who can. If anyone has been hurt during a dream, say so out loud.
From there, the Model of Care for Dementia in Ireland, published in 2023, sets out two tiers. Memory Assessment and Support Services (MASS) are the local tier, with a target of one service per 150,000 people carrying out around 300 assessments a year, and a standard that 80% of people receive their results within three months. Regional Specialist Memory Clinics (RSMCs) handle the complex and atypical cases, which is exactly where LBD belongs.
The honest picture is worth having before you go looking. As of March 2026, four of the minimum five recommended regional clinics are operational, with a fifth for North Dublin committed to in the HSE National Service Plan 2026 and the site still under consideration. Of ten locations originally prioritised for a new memory service because they had little or none, three are running, in Cavan/Monaghan, Mayo and Sligo/Leitrim, with six more due to be advanced during 2026. If you are rural, that gap is not abstract.
Useful supports while you wait: the Alzheimer Society of Ireland’s National Helpline on 1800 341 341, open Monday to Friday from 10am to 5pm and Saturday from 10am to 4pm; Lewy Body Ireland at lewybodyireland.org, set up by families and people living with the condition, which also marks World Lewy Body Dementia Day each 28 January; and the HSE’s dementia service finder for what exists locally.
The practical things that help
Make the bedroom safe. If dreams are being acted out, move the locker, lower the bed, clear the floor. Many partners sleep better in a separate room, and there is no failure in that.
Treat falls as a symptom, not clumsiness. Blood pressure that drops on standing is common in LBD and is a direct cause of dizziness and falls. Ask for lying and standing blood pressure to be measured, and for a medication review.
Improve the lighting. Fluctuations tend to be worse in dim, cluttered rooms, which is also where hallucinations find their raw material.
Deal with the driving question early. In Ireland a diagnosis of dementia must be notified to the National Driver Licence Service and to your insurer, with a D501 medical report from your doctor. Group 1 driving may continue in the early stages after review, but the combination of fluctuating alertness and visual symptoms makes this one to face rather than postpone.
Sort the legal ground while capacity is clear. An Enduring Power of Attorney made now, under the Assisted Decision-Making (Capacity) Act 2015, is immeasurably easier than the alternative later.
And if you are the person doing the supporting, look at what is available to you rather than assuming there is nothing: our guides to caring for someone with dementia at home and to the HSE home support service are the places to start.
Why the name matters
A diagnosis does not change the condition. It changes almost everything around it: which medicines are safe, which are likely to help, what the hallucinations mean, and whether a family spends years believing they are watching something they cannot name. Where the wrong prescription carries real risk, getting the name right is not an administrative nicety. It is part of the treatment.
If symptoms at home have never quite added up, this one is worth raising by name at your next appointment. At Críonna Health we write about ageing in Ireland as it actually works, including the parts of the system that have not been built yet.
This article is for general information and is not a substitute for medical advice. If you are worried about symptoms, speak to your GP.
📷 Photo by bahareh moradian on Unsplash
