Lewy body dementia and Alzheimer’s disease are both common types of dementia. People with either condition experience changes in the brain that can cause physical, cognitive, and behavioral symptoms.

This article examines the similarities and differences of both conditions, including symptoms, treatment, diagnosis, and outlook.

A person underwater who may have Lewy body dementia or Alzheimer's disease.Share on Pinterest
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Lewy body dementia (LBD) is one of the most common types of dementia. It occurs in over 1 million people in the United States.

LBD occurs when alpha-synuclein, a type of protein, builds up in the brain to form deposits called Lewy bodies. Lewy bodies cause chemical changes in the brain, which affect movement, behavior, mood, and thinking.

Learn more about Lewy body dementia.

Alzheimer’s is the most common type of dementia, accounting for 60–80% of dementia cases.

Alzheimer’s disease occurs when changes to the brain prevent nerve cells from working properly. This brain damage affects memory, personality, and the ability to carry out everyday tasks.

Learn more about Alzheimer’s disease.

According to the Alzheimer’s Association, Alzheimer’s disease and LBD can overlap. Lewy bodies can occur in people with Alzheimer’s, and plaques and tangles — key markers of Alzheimer’s disease — occur in many individuals with LBD.

Although LBD and Alzheimer’s disease may share similar symptoms, they are different conditions and do not appear to lead to the other.

The following table compares the two conditions.

Lewy body dementiaAlzheimer’s disease
SymptomsSymptoms include:
• changes in thinking and reasoning
• confusion and alertness that varies from one day to the next
• visual hallucinations
• delusions
• sleep disturbances
• memory loss that is less prominent than in Alzheimer’s but still significant
• slowness and changes in movement
• difficulty interpreting visual information
Symptoms may worsen over time. Mild symptoms include:
memory loss
• repeating questions
• wandering and getting lost
• losing and misplacing items
• changes in personality and mood
anxiety
• aggression
• judgment difficulties
• taking more time to complete everyday tasks
Age of onsetOccurs between 50–85 years.Occurs during the mid-60s, although it can be earlier.
CausesResearchers have not identified a cause.Causes include a combination of lifestyle, environmental, and genetic factors.
Risk factorsRisk factors include:
• older age
Parkinson’s disease
REM sleep disorder
Risk factors include:
• older age
• genetics
• cardiovascular conditions
• head injury
TreatmentMedication, lifestyle changes, cognitive and behavioral therapy can treat symptoms and slow disease progression.Medication, lifestyle changes, cognitive and behavioral therapy can treat symptoms and slow disease progression.
Life expectancyMost people live for an average of 5–8 years but could be up to 20 years.Most people live for an average of 4–8 years but could be up to 20 years.
OutlookThere is no cure, but treatment can help manage symptoms. The symptoms may vary from day to day.There is no cure, while symptoms worsen over time. Medications can help manage symptoms and slow disease progression.

The following are symptoms of LBD and Alzheimer’s disease.

LBD

Symptoms of LBD can include:

  • altered thinking and reasoning
  • levels of confusion and changes in alertness throughout the day or across different days
  • changes in movement, similar to Parkinson’s symptoms, such as slowness and imbalance in gait
  • visual hallucinations
  • delusions
  • difficulty interpreting visual information
  • sleep disturbances
  • memory problems
  • depressed mood

Alzheimer’s disease

Symptoms of Alzheimer’s disease can include:

  • memory problems
  • difficulty finding words or communicating
  • vision issues
  • spatial awareness issues
  • impaired reasoning
  • impaired judgment
  • changes to personality and behavior
  • difficulty carrying out everyday tasks
  • confusion
  • changes in sensory processing

The symptoms and their severity can depend on the stage of Alzheimer’s disease.

Learn more about the stages and associated symptoms of Alzheimer’s.

Comparison of symptoms

The following table compares some of the symptoms of LBD and Alzheimer’s disease.

LBDAlzheimer’s disease
CognitionDifficulties with memory, reasoning, executive functions, and visual and spatial skills, but this can vary significantly from day to day.Difficulties with memory, reasoning, executive functions, and visual and spatial skills, which may worsen over time.
Physical movementSymptoms are similar to Parkinson’s, including rigidity, muscle stiffness, and tremors. People may also faint or fall.People may have spatial awareness issues.
Facial expressionsPeople with LBD may have reduced facial expression.Apathy as a result of Alzheimer’s may lead to a reduction in facial expressions and emotional responsiveness. Those with Alzheimer’s may also have difficulty recognizing emotions in other people’s facial expressions.
Visual hallucinationsUp to 80% of people with LBD may have intense visual hallucinations, beginning in the early stages of the condition.As Alzheimer’s progresses, people may have hallucinations, including other senses such as smell or hearing.
REM sleep behavior disorder (RBD)Some people with LBD may experience RBD, a condition in which people act out their dreams, which can cause dangerous actions.RBD is not a symptom of Alzheimer’s.

Both conditions typically affect older adults.

LBD

The age of onset for LBD can range from 50–85 years, typically when people are in their mid-to-late 70s.

LBD may continue for around 6 years. People may develop different symptoms over time that can vary in severity from day to day.

Alzheimer’s disease

Most people with Alzheimer’s disease have late-onset Alzheimer’s, with symptoms beginning in the mid-60s. Individuals may develop early-onset Alzheimer’s disease between the 30s and mid-60s.

Alzheimer’s disease is a progressive condition, meaning symptoms worsen over time as the disease moves through mild, moderate, and severe stages.

The following are the causes and risk factors for each condition.

LBD

Researchers are not sure of the exact cause of LBD, but the condition may have links to changes in neurotransmitters, which are chemical messengers.

Lewy bodies cause a loss of certain nerve cells in the brain that produce the neurotransmitters acetylcholine and dopamine. These are important for many functions, including memory, learning, behavior, cognition, and sleep.

Risk factors for LBD include:

  • older age
  • Parkinson’s disease
  • REM sleep behavior disorder
  • having a family member with LBD, although it is not a genetic condition

Alzheimer’s disease

A combination of genetic, environmental, and lifestyle factors may lead to the brain damage that causes Alzheimer’s disease. A build-up of amyloid and tau proteins in the brain leads to the formation of plaques and tangles that affect nerve cell function.

Risk factors for Alzheimer’s disease may include:

  • older age
  • genetics
  • having a family member with the condition
  • vascular conditions, such as high blood pressure, heart disease, diabetes, or stroke
  • obesity
  • head injury
  • older adults who are Latino or African American may have a higher risk than white adults, which may be due to higher rates of vascular conditions

There is no cure for LBD or Alzheimer’s disease. However, medications and lifestyle changes may help manage symptoms and slow the progression of dementia.

LBD

Although there is no cure for the brain damage in LBD, treatments can help relieve symptoms and may include:

  • cholinesterase inhibitor drugs
  • antidepressants, such as selective serotonin reuptake inhibitors, if depression is a symptom
  • clonazepam to treat RBD

However, treatment with antipsychotics can be toxic to people with LBD and can be very dangerous. In these cases, lower-potency antipsychotics may be safer.

Alzheimer’s disease

Treatment for Alzheimer’s disease focuses on relieving symptoms, preserving mental function, and slowing disease progression.

Treatment may include:

  • medications, such as aducanumab
  • cognitive training
  • behavioral therapy
  • physical activity

Additionally, a healthcare professional may prescribe the following only if other methods are not effective:

  • sleep aids
  • anti-anxiety drugs
  • anti-convulsants
  • antipsychotics

Each condition worsens over time, while life expectancy may vary.

LBD

According to the Lewy Body Dementia Association, the outlook and life expectancy for people with LBD varies between individuals and may depend on overall health and any co-existing illnesses.

This makes it challenging to provide a precise estimate for life expectancy, as people may live anywhere between 2–20 years after developing symptoms. An average estimate of life expectancy for people with LBD is 5–8 years after initial symptoms occur.

However, treatment can help relieve symptoms and improve quality of life.

Alzheimer’s disease

Symptoms of Alzheimer’s disease worsen over time, as stages of the disease progress from mild to severe. Life expectancy and outlook can vary for each individual, depending on factors such as overall health.

The average life expectancy of a person with Alzheimer’s disease is 4–8 years following a diagnosis, but some people may live up to 20 years after.

Treatment can help relieve certain symptoms, slow a person’s cognitive decline, and improve quality of life.

There is no sure way to prevent LBD or Alzheimer’s disease. However, a person can help to reduce their chance of developing them.

LBD

There is currently no prevention for LBD, but some research suggests that a healthy lifestyle may help reduce the risk of age-related dementia. This includes:

  • regular exercise
  • mental stimulation
  • a nutritious, balanced diet

Alzheimer’s disease

People could reduce the risk of Alzheimer’s disease by focusing on risk factors they can control, such as:

  • regular exercise
  • healthy diet
  • reducing the risk of head injury by wearing a helmet in high-risk sports and wearing a seat belt in vehicles
  • avoiding tobacco smoke
  • limiting alcohol
  • mental stimulation
  • keeping socially active
  • reducing cardiovascular health risks

Healthcare professionals will diagnose LBD and Alzheimer’s disease using a variety of tests.

LBD

To diagnose LBD, doctors may:

  • take a medical history and examine symptoms
  • examine symptoms and any behavioral changes
  • test cognition with memory, language, and problem-solving tests
  • use blood tests
  • analyze brain scans

Alzheimer’s disease

To diagnose Alzheimer’s disease, doctors may:

  • take a medical history
  • examine symptoms and any behavioral changes
  • test cognition, with memory, language, and problem-solving tests
  • take blood and urine tests
  • take brain scans

People can contact a doctor if they or a loved one show any signs of LBD or Alzheimer’s disease. Some symptoms may relate to another condition, a side effect from medication, or a vitamin deficiency.

It is important to seek early diagnosis and treatment to help relieve symptoms and slow down the progression of the disease.

LBD and Alzheimer’s disease are common types of dementia. Both conditions are brain disorders that can affect a person’s cognitive ability.

Although there is no cure for either condition, treatment may help relieve symptoms, slow disease progression, and improve quality of life.