What is Lewy Body Dementia? – Causes and Symptoms

Lewy body dementia (LBD) is a progressive brain disorder that affects thinking, movement, behaviour, sleep and other bodily functions. It develops when abnormal deposits of a protein called alpha-synuclein, known as Lewy bodies, accumulate in brain cells and interfere with normal brain function.

People with Lewy body dementia may experience visual hallucinations, changes in attention and alertness, memory difficulties, muscle stiffness and problems with walking. Unlike some other types of dementia, its symptoms can fluctuate considerably, with a person appearing alert at one moment and confused or drowsy at another.

Lewy body dementia is one of the most common forms of dementia after Alzheimer’s disease. Although no cure currently exists, medical treatment and appropriate care can help manage symptoms and support quality of life.

This guide explains the causes, early symptoms, diagnosis, treatment options and practical care strategies for people living with Lewy body dementia.

What Is Lewy Body Dementia?

Lewy body dementia is a neurological condition associated with the abnormal accumulation of alpha-synuclein protein inside nerve cells. These deposits affect brain regions involved in memory, attention, movement, perception and the regulation of bodily functions.

The condition can cause a combination of cognitive, physical, behavioural and sleep-related symptoms. Some people initially experience changes in thinking and perception, while others develop movement difficulties before noticeable cognitive decline.

Lewy body dementia is an umbrella term for two closely related diagnoses:

• Dementia with Lewy bodies (DLB): Cognitive symptoms develop before or around the same time as movement symptoms.
• Parkinson’s disease dementia (PDD): A person develops Parkinson’s disease first, and dementia appears later in the course of the illness.

Clinicians generally distinguish these conditions using the timing of cognitive and movement symptoms. Both involve Lewy body pathology and can produce similar difficulties.

Causes of Lewy Body Dementia

The exact cause of Lewy body dementia remains unknown. Researchers understand that abnormal alpha-synuclein deposits play a central role, but they have not established precisely why these deposits develop in some people.

1. Abnormal Alpha-Synuclein Protein Deposits

Alpha-synuclein is a protein found naturally in nerve cells. In Lewy body dementia, the protein accumulates abnormally and forms deposits called Lewy bodies.

These deposits are associated with damage to brain cells and disruptions in communication between neurons. As affected brain regions lose normal function, a person may develop problems with attention, movement, memory and behaviour.

2. Changes in Brain Chemicals

Lewy body dementia affects neurotransmitters, which are chemicals that help nerve cells communicate.

Two important neurotransmitters are:

• Acetylcholine: Supports attention, learning and memory.
• Dopamine: Helps regulate movement, motivation and other brain functions.

Changes in these chemical systems help explain why people with Lewy body dementia can experience both cognitive difficulties and symptoms similar to Parkinson’s disease.

3. Genetic and Environmental Factors

Age is a major risk factor for Lewy body dementia. Researchers have also identified genetic associations with the condition, but most cases do not follow a straightforward inherited pattern.

A family history of Lewy body dementia or related neurological conditions may be relevant, but it does not mean that a person will inevitably develop the disease.

Scientists continue to investigate how genetic susceptibility, ageing and other biological factors contribute to its development.

Symptoms of Lewy Body Dementia

The symptoms of LBD vary from person to person and often progress over time. The condition is characterised by a combination of cognitive, motor, and behavioural symptoms, making diagnosis challenging.

1. Fluctuations in Attention and Alertness

A person may experience unpredictable changes in concentration, awareness and mental clarity. They might hold a coherent conversation at one time but become confused, sleepy or unresponsive to their surroundings later.

These changes can occur over minutes or hours and may make daily activities difficult to plan. Sudden changes in alertness should not automatically be attributed to dementia. An abrupt deterioration can also indicate an infection, medication reaction or another medical problem that requires prompt assessment.

2. Hallucinations and Delusions

Visual hallucinations are a characteristic symptom of Lewy body dementia. A person may see people, animals, objects or shapes that are not actually present.

These experiences can appear vivid and realistic. Some people find them frightening, while others may not feel distressed by them.

Caregivers should respond calmly and avoid arguing about what the person sees. A reassuring response and a safe environment may help reduce distress.

3. Motor Symptoms

LBD shares many symptoms with Parkinson’s disease, including muscle stiffness, tremors, slow movement (bradykinesia), and balance problems. These symptoms can lead to frequent falls and mobility issues.

4. Sleep Disorders

Some people develop REM sleep behaviour disorder. During normal REM sleep, the body generally prevents most physical movements associated with dreams. In this sleep disorder, a person may physically act out their dreams by shouting, kicking, punching or moving their arms.

Sleep disturbances can occur before other recognisable symptoms of Lewy body dementia. They may also increase the risk of injury to the affected person or their sleeping partner.

A healthcare professional can assess persistent or unusual sleep behaviours and recommend appropriate management.

5. Autonomic Nervous System Dysfunction

LBD can affect the autonomic nervous system, leading to symptoms such as low blood pressure (causing dizziness or fainting), digestive problems, urinary incontinence, and irregular heart rate.

6. Mood and Behavioural Changes

Lewy body dementia can affect emotional well-being and behaviour. Symptoms may include:

• Depression.
• Anxiety.
• Reduced motivation.
• Irritability.
• Increased confusion.
• Changes in social behaviour.

These symptoms may arise from changes in brain function, distress caused by other symptoms or the difficulties of everyday life. A medical assessment can help identify appropriate support.

What Is the Difference Between Lewy Body Dementia and Alzheimer’s Disease?

Lewy body dementia and Alzheimer’s disease both cause progressive cognitive decline, but they often present differently.

Feature	Lewy body dementia	Alzheimer’s disease
Early cognitive symptoms	Attention, visual perception and executive-function difficulties may be prominent	New learning and memory difficulties are often prominent
Visual hallucinations	A characteristic early symptom in some people	More commonly occur later or with other contributing factors
Alertness	Fluctuations can be pronounced	Decline is often more gradual and consistent
Movement	Parkinsonian symptoms may occur	Significant movement symptoms are not usually an early defining feature
Sleep	REM sleep behaviour disorder is associated with the condition	Sleep disturbances can occur, but the characteristic pattern differs
Treatment	Symptom-focused treatment and supportive care	Symptom-focused treatment and supportive care

These are general patterns rather than strict rules. Symptoms overlap, and some people have more than one type of brain pathology. A specialist assessment is needed to distinguish between conditions accurately.

How Is Lewy Body Dementia Diagnosed?

No single test can confirm every case of Lewy body dementia. Doctors generally combine a person’s medical history, symptom pattern, physical examination and cognitive assessment.

The diagnostic process may include the following:

Medical History and Symptom Assessment

A clinician may ask when the symptoms began, how they have changed and whether the person experiences hallucinations, fluctuating attention, sleep disturbances or movement difficulties.

Information from a family member or caregiver can be helpful because symptoms may vary throughout the day.

Cognitive and Neurological Assessments

Cognitive tests can assess attention, memory, language, problem-solving and visual-spatial abilities. A neurological examination may identify movement changes, muscle stiffness or balance difficulties.

Blood Tests and Brain Imaging

Blood tests can help identify other conditions that may contribute to cognitive changes. MRI or CT scans may help exclude other causes of symptoms or identify structural changes.

In selected cases, doctors may recommend specialised imaging or sleep studies to support the diagnosis.

Because symptoms overlap with other conditions, assessment by a neurologist or another clinician experienced in dementia can be valuable.

What Are the Treatment Options for Lewy Body Dementia?

There is currently no cure for Lewy body dementia. Treatment focuses on managing symptoms, maintaining function, supporting independence and improving quality of life.

The appropriate treatment plan depends on the person’s symptoms, other medical conditions and response to medication.

1. Medicines for Cognitive Symptoms

Doctors may prescribe cholinesterase inhibitors, such as rivastigmine or donepezil, to help manage cognitive symptoms in some people. These medicines may also improve certain behavioural symptoms or hallucinations.

Memantine may be considered for some patients, depending on the clinical situation.

These medicines do not cure Lewy body dementia or stop its progression. Their benefits and potential side effects require medical review.

2. Treatment for Movement Problems

Levodopa-based medicines may help some people with stiffness and slowed movement. However, they can sometimes worsen confusion or hallucinations.

Doctors must balance potential improvements in mobility against these risks and adjust treatment according to the person’s response.

3. Managing Hallucinations and Behavioural Symptoms

Hallucinations do not always require medication, particularly when they do not distress the person or create a safety concern.

A calm environment, reassurance, adequate lighting and predictable routines may help reduce confusion.

Some antipsychotic medicines can cause severe adverse reactions in people with Lewy body dementia. They may worsen movement symptoms, confusion or sedation. Never start or stop these medicines without medical guidance.

4. Therapy and Supportive Care

Non-drug approaches can help people manage everyday challenges.

• Physiotherapy: Supports mobility, balance and safe movement.
• Occupational therapy: Helps people adapt everyday activities and living environments.
• Speech and language therapy: Can help with communication and swallowing difficulties.
• Cognitive and psychological support: May help maintain engagement and address emotional challenges.
• Caregiver education: Helps families understand symptoms and respond safely.

A coordinated care plan can address changing needs as the condition progresses.

How Can Caregivers Support Someone With Lewy Body Dementia?

Caregivers can play an important role in helping people maintain comfort, dignity and independence.

Maintain a Predictable Routine

Consistent daily schedules can reduce uncertainty. Keep regular times for meals, medication, sleep and activities where possible.

Offer one instruction at a time and allow sufficient time for the person to respond.

Make the Home Safer

Reduce fall risks by removing loose rugs, improving lighting and keeping walkways clear. Install suitable grab rails or other mobility aids when recommended by a professional.

Review the home environment regularly as mobility and cognitive abilities change.

Respond Calmly to Hallucinations

If the person sees something that is not present, acknowledge their feelings rather than arguing about the experience. Reassure them and redirect attention gently when appropriate.

If hallucinations become distressing, frequent or unsafe, seek medical advice to assess possible causes and treatment options.

Encourage Suitable Physical and Social Activities

Walking with assistance, listening to music, gardening or engaging in familiar hobbies may support well-being when these activities match the person’s abilities.

Allow rest when needed and adapt activities to avoid unnecessary frustration or fatigue.

Look After Caregiver Well-Being

Caring for someone with progressive dementia can place considerable demands on family members. Respite care, caregiver support groups, counselling and help from other relatives can reduce pressure.

Caregivers should discuss their own support needs with healthcare professionals or local dementia services.

Conclusion

Lewy Body Dementia is a complex and progressive disorder that affects cognitive, motor, and behavioural functions. While its exact cause remains unclear, factors such as genetics, age, and neurological conditions may contribute to its development. Early symptoms, including cognitive fluctuations, hallucinations, and motor impairments, often lead to misdiagnosis. Understanding these symptoms can help in seeking timely medical intervention, improving quality of life for both patients and caregivers.