What is dementia with Lewy bodies?
Dementia with Lewy bodies (often shortened to DLB) is a type of dementia caused by tiny clumps of protein inside brain cells. These clumps are called Lewy bodies, after the scientist who first described them.
The NHS explains that Lewy bodies build up in parts of the brain that control thinking, visual perception and movement. Over time, they damage brain cells.
Alzheimer’s Society says around 5% of people with a dementia diagnosis are recorded as having DLB. It also says scientists think it may be under-diagnosed, so the true number could be much higher. One reason is that its symptoms overlap with Alzheimer’s disease and Parkinson’s disease.
Symptoms
DLB shares some symptoms with Alzheimer’s disease and some with Parkinson’s disease. Memory may be less affected early on than in Alzheimer’s disease. The NHS lists these main symptoms.
Changes in alertness
Attention and alertness can change a lot, over minutes, hours or days. A person may be chatty and clear one moment, then very drowsy, staring or confused the next. Families sometimes describe these as “good days and bad days”.
Hallucinations
Many people see things that are not there. These are often detailed, such as people or animals in the room. Some people hear or smell things that are not there. Hallucinations are not always frightening, but they can be.
Movement problems
Symptoms like those of Parkinson’s disease are common. These include slow movement, stiff limbs, a shuffling walk and tremor (shaking).
Sleep problems
Some people act out their dreams while asleep. They may shout, kick or lash out. This is called REM sleep behaviour disorder. It can start years before other symptoms. People may also be very sleepy during the day.
Other symptoms
- problems with thinking, planning and judging distances
- fainting, dizziness, unsteadiness and falls
- low mood, anxiety or loss of interest
- believing things that are not true (delusions)
Parkinson’s disease dementia
Parkinson’s disease is also linked to Lewy bodies. Alzheimer’s Society says about a third of people with Parkinson’s disease eventually develop dementia. This is called Parkinson’s disease dementia.
The two conditions are very similar. The main difference is the order in which symptoms appear.
| Feature | Dementia with Lewy bodies | Parkinson’s disease dementia |
|---|---|---|
| What comes first | Thinking problems start before, or around the same time as, movement problems | Movement problems come first. Thinking problems develop many years later |
| Main features | Changing alertness, hallucinations, movement problems, sleep changes | Slowness of thinking, poor focus, hallucinations, sleep and mood changes |
| Underlying cause | Lewy bodies | Lewy bodies |
For people with Parkinson’s disease, NICE refers doctors to its separate Parkinson’s disease guideline for managing dementia. The same medicine cautions apply.
The antipsychotic warning
Antipsychotics are sometimes used for hallucinations, agitation or aggression in other types of dementia. In DLB and Parkinson’s disease dementia, doctors take extra care.
Practical steps for families:
- Carry a note or card with the diagnosis, and ask for it to be recorded clearly in hospital notes.
- Tell paramedics, hospital staff, care home staff and pharmacists about the diagnosis.
- Ask the doctor about any new medicine and whether it is suitable for DLB.
- Never stop or change medicines without advice from the prescriber.
Diagnosis
The NHS says there is no single test for DLB. Diagnosis involves:
- a detailed history of symptoms, ideally from the person and someone who knows them well
- memory and thinking tests
- blood tests to rule out other causes
- brain scans, such as MRI or CT
NICE says specialists should use a type of scan called 123I-FP-CIT SPECT (sometimes called a DaTscan) if the diagnosis is uncertain. NICE also says DLB should not be ruled out based only on a normal scan result.
Because DLB can be mistaken for other conditions, it can help to write down the pattern of symptoms before appointments. Note hallucinations, sleep changes, falls and good and bad days. See getting a diagnosis.
Treatment
There is no cure for DLB. Treatment aims to ease symptoms.
- Medicines for thinking and hallucinations: NICE recommends offering donepezil or rivastigmine for mild to moderate DLB. For severe DLB, these or memantine may be considered.
- Movement problems: Parkinson’s medicines may help, but they can make hallucinations or confusion worse. Doctors try to balance the benefits and side effects.
- Therapies: the NHS lists physiotherapy, occupational therapy and speech and language therapy. These can help with movement, daily tasks, communication and swallowing.
- Sleep and mood: tell the doctor about sleep problems and low mood, as these can be treated.
See treatment for more.
Tips for daily life
- Hallucinations: stay calm. It usually does not help to argue. Gently acknowledge what the person is experiencing, and reassure them. Good lighting can reduce shadows that may be misread.
- Fluctuations: plan activities and appointments for times of day when the person tends to be more alert.
- Falls: remove trip hazards, use good lighting and ask about a falls assessment.
- Fainting and dizziness: encourage the person to stand up slowly and drink enough fluids.
- Sleep: if the person acts out dreams, make the bedroom safe by moving sharp or hard objects away from the bed.
See living well and caring for someone for more practical ideas.
Where to get support
Dementia UK’s Admiral Nurses and Alzheimer’s Society can offer advice on DLB and Parkinson’s disease dementia. See support and helplines.