🧠 Another Type of Dementia You Should Know — Lewy Body Dementia (DLB)
Lecturer: Professor Kenji Wada,
Head of the Department of Geriatric Medicine, Kawasaki Medical School General Medical Center
Board Member, Japanese Society for Dementia / Chair, National Dementia Care Guideline Committee
1. What Is Dementia?
Dementia refers to a state in which cognitive abilities, once normally developed, decline persistently due to brain disease, leading to difficulties in daily and social life.
When this occurs without loss of consciousness, it is diagnosed as dementia.
In Japan today, about 15% of people over 65 live with dementia.
Lifetime prevalence is estimated at 64.8% for women and 40.8% for men—meaning that two out of three women and two out of five men will experience some form of dementia during their lifetime.
2. Major Types of Dementia
Although dementia has many causes, it is broadly divided into four major categories:
a. Alzheimer’s Disease
The most common type, characterized primarily by memory loss.
b. Vascular Dementia
Caused by damage to the brain’s blood vessels, such as from strokes.
c. Frontotemporal Dementia (FTD)
Marked by changes in emotion, language, and social behavior.
d. Lewy Body Dementia (DLB)
The focus of today’s lecture.
3. What Are Lewy Bodies?
Lewy bodies are abnormal protein clumps found inside brain nerve cells.
They are formed from alpha-synuclein, a protein normally involved in nerve signal transmission.
When this protein accumulates abnormally, it impairs cellular function.
When Lewy bodies spread widely throughout the brainstem (which controls movement, as in Parkinson’s disease) and the cerebral cortex (responsible for thinking), both motor symptoms and cognitive decline appear at the same time.
4. How Common Is It?
Lewy Body Dementia accounts for about 15–20% of all dementia cases, making it the second most common form after Alzheimer’s.
As societies age, this proportion is expected to rise.
5. Key Symptoms
(1) Fluctuating Cognition
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Levels of alertness and clarity vary dramatically from day to day—or even within a single day.
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For example, someone may speak clearly in the morning but become confused or fail to recognize family members by afternoon.
(2) Visual Hallucinations
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The person may vividly see people, animals, or insects that are not there.
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These hallucinations often feel completely real, causing fear or distress.
(3) Parkinsonian Symptoms
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Stiffness, slowed movement, small steps, and tremors of the hands.
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Unsteady posture and increased risk of falls.
(4) REM Sleep Behavior Disorder
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Acting out dreams physically—talking, shouting, or moving during sleep.
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This can appear years before dementia develops, serving as an early warning sign.
(5) Autonomic Nervous System Symptoms
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Orthostatic hypotension (dizziness when standing up), constipation, urinary problems, excessive sweating, and difficulty regulating body temperature.
6. Does the Person Notice These Changes?
In early stages, many people sense that something is wrong.
However, because symptoms fluctuate, they may believe they are “fine on good days,” delaying medical attention.
7. Why Differential Diagnosis Is Crucial
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DLB is easily confused with Alzheimer’s disease.
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However, medications for Alzheimer’s (such as donepezil) can cause severe side effects in DLB if used incorrectly.
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People with DLB are also extremely sensitive to antipsychotic drugs; even small doses can cause serious sedation or movement problems.
8. How It Is Diagnosed
Diagnosis combines:
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Detailed medical and family history
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Cognitive tests (e.g., MMSE, MoCA)
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Brain imaging (MRI or PET) to detect Lewy body patterns
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Evaluation of sleep disorders and autonomic symptoms
A diagnosis of DLB is made when fluctuating cognition, visual hallucinations, and Parkinsonian features occur together.
9. Treatment Options
(1) Medication
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Donepezil
The main approved drug for DLB; it can improve cognition, reduce hallucinations, and stabilize fluctuations.
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Rivastigmine and Galantamine
Similar cholinesterase inhibitors used outside Japan.
⚠️ Caution: Antipsychotic drugs (e.g., risperidone, haloperidol) can be dangerous for DLB patients.
They should only be used under a neurologist’s close supervision.
(2) Non-Pharmacological Approaches
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Maintain a regular daily rhythm.
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Ensure a safe environment—good lighting, handrails, no floor clutter.
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Encourage social engagement, music, or gentle exercise.
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For severe sleep disturbances, improve sleep hygiene and consult a specialist.
10. What Families Should Know
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Understand that symptoms may change drastically within a single day; apparent recovery can be misleading.
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Avoid confronting hallucinations directly; respond with empathy instead.
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Prevent falls and ensure home safety.
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Seek medical advice early for sleep or movement issues.
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Manage caregiver stress and build a support network—family wellbeing matters too.
11. Where to Seek Help
Start with a neurologist or psychiatrist.
Specialized dementia clinics or geriatric centers are ideal, as they provide integrated diagnosis, treatment, and family counseling.
12. Summary Table — Key Features of Lewy Body Dementia
| Category | Main Symptoms | Distinguishing Features |
|---|
| Cognitive | Fluctuating attention and alertness | Varies day to day |
| Hallucinations | Vivid visual images | People, animals, insects |
| Motor | Parkinsonian stiffness and tremor | Slow and rigid movement |
| Sleep | REM sleep behavior disorder | Acting out dreams |
| Autonomic | Orthostatic dizziness, constipation | Non-motor involvement |
| Medication Sensitivity | Extreme reaction to antipsychotics | Use with great caution |
13. Prevention and Lifestyle Management
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Regular physical activity (e.g., walking, light strength training)
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Balanced diet (Mediterranean-style recommended)
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Adequate sleep and stress reduction
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Active social life
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Control of chronic conditions such as hypertension, diabetes, and high cholesterol
14. Professor Wada’s Message
“Dementia is not an unavoidable fate.
Early recognition and joint preparation make a real difference.
With proper diagnosis, treatment, and understanding from family,
even Lewy Body Dementia can be managed — allowing life to continue with dignity and meaning.”
Would you like me to prepare this English version in a printable bilingual format (Korean on the left, English on the right) for sharing with your son and other family members?
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