Lewy Body Dementia

What Lewy body dementia is

Lewy bodies are clumps of a protein called alpha-synuclein inside nerve cells. They damage areas that control thinking, visual processing, movement, sleep and automatic body functions such as blood pressure. They also lower levels of two brain chemicals: acetylcholine (memory and attention) and dopamine (movement).

"Lewy body dementia" is an umbrella term for two related diagnoses that differ in timing:

Lewy body dementia symptoms

Core features

• Fluctuating cognition and alertness: marked swings in attention and clarity, from hour to hour or day to day. The person may stare into space, seem drowsy for long periods or speak in a disorganized way, then be lucid later.
• Visual hallucinations: recurrent, detailed and well formed, often of people, children or animals. Early on, many people know they are not real and are not frightened.
• REM sleep behavior disorder: acting out vivid dreams by talking, shouting, punching or kicking. It often begins years or even decades before other symptoms. See REM sleep behavior disorder.
• Parkinsonism: slowness, stiffness, shuffling walk, reduced facial expression and soft voice. Tremor is less prominent than in Parkinson's disease.

Other common features

• attention, planning and visual-spatial problems (judging distances, misjudging steps) more than early memory loss
• falls and unexplained episodes of unresponsiveness
• drops in blood pressure on standing, causing dizziness and fainting (orthostatic hypotension)
• constipation, urinary urgency and erectile dysfunction
• loss of smell
• daytime sleepiness
• depression, anxiety, apathy and delusions (fixed false beliefs)
• severe sensitivity to antipsychotic medicines

Lewy body dementia vs Alzheimer's disease

Many people have both Lewy bodies and Alzheimer's changes in the brain, which makes the picture mixed.

Causes and risk factors

The cause of Lewy body formation is not fully understood. Risk factors include:

• age over 60
• male sex
• REM sleep behavior disorder, which is a strong early warning sign
• family history of Lewy body dementia or Parkinson's disease, and certain gene variants such as GBA and APOE e4

Most cases are not inherited.

Diagnosis

No single test confirms Lewy body dementia during life. Diagnosis is based on the 2017 international consensus criteria, which combine clinical features with biomarkers:

• History from the person and family: fluctuations, hallucinations, sleep behavior, falls and medicines.
• Cognitive testing, which typically shows more trouble with attention and visual tasks than with memory.
• Neurological examination for parkinsonism.
• DaT scan (dopamine transporter SPECT): shows reduced dopamine activity in the brain, supporting LBD over Alzheimer's.
• Sleep study (polysomnography): confirms REM sleep without the normal muscle paralysis.
• Cardiac MIBG scan, used in some countries, which shows loss of heart nerve signals.
• Alpha-synuclein tests: skin biopsy and spinal fluid "seed amplification" tests can detect abnormal alpha-synuclein and are increasingly available.
• Blood tests and brain MRI to exclude other causes, such as vitamin B12 deficiency, thyroid disease, strokes or tumors.

The disease is often misdiagnosed early as Alzheimer's disease, Parkinson's disease or a psychiatric illness.

Treatment

Thinking, alertness and hallucinations

Cholinesterase inhibitors (rivastigmine, donepezil, galantamine) often work better in Lewy body dementia than in Alzheimer's. They can improve attention, alertness and hallucinations. Side effects include nausea, diarrhea, slow pulse and vivid dreams. Memantine is sometimes added.

Antipsychotic cautions

Up to half of people with LBD react badly to antipsychotic drugs, with sudden severe rigidity, sedation, confusion, falls and sometimes a life-threatening reaction similar to neuroleptic malignant syndrome. Older antipsychotics such as haloperidol should be avoided. If hallucinations or delusions are severe, a specialist may cautiously try low-dose quetiapine, clozapine or pimavanserin. Carry a medical alert card listing this sensitivity.

Movement problems

Carbidopa-levodopa can ease stiffness and slowness but may worsen hallucinations and confusion, so it is started at a low dose. Physical therapy helps with walking, strength and fall prevention.

Sleep, mood and body functions

• Melatonin or, with caution, clonazepam for REM sleep behavior disorder, plus a safe bedroom (padding, moving the bed from furniture).
• Antidepressants such as SSRIs for depression and anxiety.
• Extra fluids and salt, compression stockings, slow standing, and sometimes medicines such as midodrine or fludrocortisone for low blood pressure on standing.
• Fiber, fluids and laxatives for constipation.

Avoid medicines with strong anticholinergic effects, including some bladder medicines, older antihistamines such as diphenhydramine and tricyclic antidepressants, because they worsen confusion.

Stages and life expectancy

Lewy body dementia progresses gradually, but its course is less predictable than Alzheimer's:

• Early: sleep behavior disorder, loss of smell, constipation, mild attention problems, occasional hallucinations. People are often still independent.
• Middle: more frequent fluctuations, falls, parkinsonism, delusions, needing help with daily tasks.
• Late: severe movement and swallowing problems, high fall risk, need for full-time care.

Average survival after diagnosis is often around 5 to 8 years, though it ranges widely from a couple of years to 20. Common causes of death are pneumonia (often from swallowing problems), falls and infections.

Caring for someone with Lewy body dementia

• Keep a symptom diary of good and bad days. Plan important activities for times of best alertness.
• Do not argue with hallucinations. Acknowledge feelings, offer reassurance, and improve lighting to reduce misperceptions.
• Remove trip hazards and use night lights. Stand up slowly.
• Look for treatable triggers of sudden decline: infections, dehydration, constipation, pain and new medicines.
• Plan early for legal, financial and care decisions while the person can take part.
• Caregiver support from groups such as the Lewy Body Dementia Association reduces strain.

Frequently asked questions

What are the first signs of Lewy body dementia?

Early signs often include acting out dreams during sleep, loss of smell, constipation and dizziness on standing, sometimes years before thinking problems. Then come swings in attention and alertness, trouble with planning and judging distances, visual hallucinations and Parkinson-like stiffness or slowness. Memory loss is often less prominent early on.

How is Lewy body dementia different from Alzheimer's?

Lewy body dementia affects attention, alertness and visual-spatial skills early, with day-to-day fluctuations, hallucinations, sleep behavior problems and movement symptoms. Alzheimer's disease mainly affects short-term memory early and declines more steadily. People with Lewy body dementia can also react severely to antipsychotic drugs.

What is the life expectancy with Lewy body dementia?

On average, people live about 5 to 8 years after diagnosis, but the range is wide, from about 2 to 20 years. Age, other health problems and how quickly falls and swallowing difficulties develop all affect survival. Good care, fall prevention and treating infections promptly help.

Is Lewy body dementia hereditary?

Most cases are not directly inherited. Having a parent or sibling with Lewy body dementia or Parkinson's disease raises the risk somewhat, and some gene variants, such as GBA, increase risk. Rare families carry genes that cause the disease more directly. Genetic testing is not routinely needed.

Why are antipsychotics dangerous in Lewy body dementia?

The brain in Lewy body dementia has very little dopamine. Antipsychotics block dopamine further, which can cause sudden severe stiffness, sedation, worse confusion, falls and occasionally a life-threatening reaction. Older drugs such as haloperidol should be avoided. If needed, specialists use low doses of safer options under close monitoring.

Can Lewy body dementia be confirmed while someone is alive?

Increasingly, yes. A DaT scan and a sleep study strongly support the diagnosis, and newer skin biopsy and spinal fluid tests can detect abnormal alpha-synuclein. A definite diagnosis still relies on brain examination after death, but a probable diagnosis using current criteria is accurate in most cases.