Dementia with Lewy bodies: symptoms, diagnosis and care

Lewy bodies are tiny clumps of protein that appear in the nerve cells of the brain. Alzheimer's Society explains that in Lewy body disease they reduce the chemicals needed to send messages in the brain and break connections between nerve cells, eventually stopping those cells working. The NHS says the same deposits are found in people with Parkinson's disease, and that in DLB they build up in areas responsible for thinking, visual perception and muscle movement.

It usually develops over many years, typically as a person approaches old age, and Lewy bodies can be developing for a long time before symptoms show. It affects men and women roughly equally, becomes more common over 65, and is rare in people under 65 according to the NHS. Almost everyone who develops it has the "sporadic" form with no clear cause, and the NHS says it usually occurs in people with no family history.

Alongside problems with thinking speed, understanding, judgement, visual perception and language, the NHS says significant memory loss may not occur until later, which is one way DLB can look different from Alzheimer's. These difficulties may be constant but typically come and go.

• Hallucinations: seeing, sometimes hearing or smelling things that are not there. The NHS says they can range from pleasant to distressing.

• Fluctuating alertness: marked, unexpected swings between alertness and confusion or sleepiness, changing over minutes or hours.

• Movement changes similar to Parkinson's disease: slow movement, stiff limbs, tremor and shuffling when walking.

• Fainting, unsteadiness and falls.

• Disturbed sleep: talking in sleep, acting out dreams, violent movements or shouting out, and sleepiness in the day.

• Swallowing problems (dysphagia), depression and anxiety.

Alzheimer's Society says that in DLB the symptoms of dementia begin before, or around the same time as, problems with movement. For people with Parkinson's disease, dementia often develops many years after the movement problems begin. It also notes that DLB has many symptoms in common with delirium and that, without knowing the person well, it can be hard to tell the two apart. The fluctuating pattern is a reason relatives' descriptions of "good days and bad days" are valuable to the assessing clinician.

Many people with DLB also have the protein build-up that causes Alzheimer's disease, which Alzheimer's Society says is common over about 80 years old and tends to make symptoms more severe and faster to progress.

The NHS advises seeing a GP early if dementia symptoms appear, especially over 65, ideally with someone who can describe the changes. The GP can do simple checks and refer to a memory clinic or another specialist. There is no single test for DLB. The NHS lists an assessment of symptoms, an assessment of mental abilities using tasks and questions, blood tests to rule out similar conditions, and brain scans such as MRI, CT or SPECT.

Telling the team about hallucinations, dream enactment, fainting spells and falls, even if they seem unrelated to memory, helps them reach the right diagnosis.

The NHS says medicine cannot stop DLB getting worse but may reduce some symptoms. Acetylcholinesterase inhibitors (donepezil, rivastigmine, galantamine) may help hallucinations, confusion and sleepiness in some people, with side effects including nausea, diarrhoea, headache, tiredness and muscle cramps. Memantine is used for moderate or severe DLB or if the first group cannot be taken.

The NHS also describes other medicines that may help specific problems: levodopa for movement difficulties (which can worsen other symptoms and needs careful monitoring), antidepressants if depressed, and clonazepam for a particular type of REM sleep behaviour disorder. It says antipsychotics such as quetiapine may help with behaviour that puts the person or others at risk but can cause serious side effects and should be avoided whenever possible. Anyone with suspected DLB who is offered a new sedative or antipsychotic, for example in hospital, should have the DLB diagnosis made clear to the prescriber.

Therapies matter too: occupational therapy for everyday problems such as dressing, speech and language therapy for communication or swallowing, physiotherapy for movement, cognitive stimulation, relaxation, music or dance, memory cafes, and home changes such as removing trip hazards, good lighting, grab bars and handrails.

Because fainting, unsteadiness and falls are listed features, the NHS points out that an injury after a fall or a chest infection from accidentally inhaling food can follow. Practical steps include keeping floors clear, good lighting, handrails, regular review of medicines that cause drowsiness or low blood pressure, and asking for a swallowing assessment if coughing at meals appears.

The NHS says how quickly DLB worsens varies. Home-based help will usually be needed and some people will eventually need a care home. It suggests thinking early about an advance decision about treatment, a plan for where to receive care, and giving a relative lasting power of attorney. Carers can look at carers' breaks and respite care and benefits for carers. Support groups named by the NHS include the Lewy Body Society, Alzheimer's Society and Dementia UK.