Difference Between Alzheimer's and Lewy Body Dementia

Lewy body dementia (LBD) and Alzheimer’s disease are two types of dementia. There are several similarities but also some clear differences between the two progressive neurological (nervous system-related) disorders.

Both diseases affect older adults though LBD occurs less often and may begin at younger ages. Memory loss is an early feature in Alzheimer's but a later one in LBD, which is known for earlier changes in sleep, perception, mood, and mobility. There is no cure for either condition.

This article takes a look at how Lewy body dementia differs from Alzheimer's disease. It also compares the causes, symptoms, and prognosis (expected outcome) for each of the conditions and outlines the different risk factors and treatments.

difference between Alzheimers and Lewy Body Dementia

Illustration by Laura Porter for Verywell Health

Lewy Body Dementia vs. Alzheimer's Disease

Lewy body dementia and Alzheimer's disease are similar but not the same. The features of dementia differ for each disorder:

  • Lewy body dementia (LBD) is a form of dementia with characteristics of Parkinson's disease that affects executive function (problem-solving), speed of thinking, memory, movement, and moods. LBD can cause visual hallucinations, problems with attention and alertness, and movement problems such as tremors and stiffness.
  • Alzheimer's disease is the more common form of dementia that primarily affects language, behavior, and memory. It mainly manifests with profound memory loss, such as trouble recalling events, recognizing people, naming objects, or learning new information.

LBD and Alzheimer's disease can appear similar in the early stages, and it is not uncommon for someone with LBD to be mistakenly diagnosed with Alzheimer's at first.

The underlying causes of Alzheimer's and LBD can and often do overlap. As a result, a person with LBD might experience Alzheimer-type changes in their brain, resulting in shared characteristics and symptoms referred to as mixed dementia.

The main differences between LBD and Alzheimer's can be summarized in as follows:

   Lewy Body Dementia Alzheimer's Disease
Age Symptoms typically appear around age 50 but can start earlier. Symptoms typically appear in the mid-60s but can appear earlier.
Prevalence 1.4 million people (U.S.) 5.8 million people (U.S.)
Causes LBD is caused by abnormal deposits of proteins called Lewy bodies in the brain. These proteins are also associated with Parkinson's disease dementia. Alzheimer's is caused by the abnormal buildup of proteins called amyloid in the brain and the abnormal formation of a protein called tau that blocks nerve signals.
Risk factors Family history and a history of anxiety and depression are known risk factors. Family history, traumatic brain injury, and being Black or Latin are known risk factors.
Symptoms LBD can affect sleep, behavior, perception, mood, alertness, awareness, problem-solving, and movement. Hallucinations are common. Memory loss may occur in the later stages. Alzheimer's causes the progressive loss of memory, awareness, and language. Hallucinations may occur in the later stages. Memory loss is typically an early feature.
Treatment There is no cure for LBD. Some symptoms can be managed with targeted treatments. There is no cure, but certain medications and targeted treatments can slow the cognitive decline.
Prognosis Survival time is between three and five years after symptoms appear. Survival time ranges from four to 10 years after symptoms appear.

What Is the Prevalence of Lewy Body Dementia?

Lewy body dementia is the second most common type of dementia, with an estimated 1.4 million people living with LBD in the United States. It is thought to be slightly more common in males than females. Because LBD is thought to be underdiagnosed, the actual number of people with the disease may be higher.

Alzheimer's disease is the most common type of dementia. As many as 5.8 million people in the United States are living with this progressive neurodegenerative disorder. Females are more affected than males but tend to live longer. Around 5% of adults ages 60 to 74 have Alzheimer's, increasing to 14% in those 75 to 84.

Causes of Lewy Body Dementia vs. Alzheimer's

Lewy body dementia is caused by the abnormal buildup of proteins, called Lewy bodies, in the brain. When clumps of these proteins accumulate, nerves in the brain start to lose their function and eventually die. The damage in the brain is widespread and affects many domains of thinking and functioning.

Alzheimer's is caused by the abnormal buildup of proteins called amyloid that leads to the formation of plaques in the brain. The abnormal twisting of another protein called tau causes neurofibrillary tangles that block signals between nerve cells. Over time, the progressive damage will kill the cells.

Risk Factors

LBD and Alzheimer's share many of the same risk factors but have some of their own as well. While less is known about LBD, there are known risk factors for this type of dementia.

Lewy Body Dementia
  • Older age (slightly younger than Alzheimer's)

  • Male sex (slightly more than females)

  • Family history of LBD or Parkinson's disease

  • Genetics (including SNCA gene mutations)

  • History of anxiety or depression

Alzheimer Disease
  • Older age (slightly older than LBD)

  • Female sex (slightly more than males)

  • Family history of Alzheimer's disease

  • Genetics (including the APOE gene mutation)

  • Traumatic brain injury

  • Being Black or Latinx

What Are Symptoms of Lewy Body Dementia?

Lewy body dementia and Alzheimer's disease have both similarities and differences in their symptoms. Here is how the two compare:

Loss of Cognition and Memory

Cognition is the mental process of acquiring knowledge and understanding through thought, experience, and the senses. With both LBD and Alzheimer's, cognition is affected but in significantly different ways.

With LBD, the loss of cognition and memory can fluctuate. On one day, a person diagnosed with LBD will not recognize a grandchild but, on the next, be able to recall the names of each of their grandchildren.

With Alzheimer's, there may be variations, but the decline is generally steady, and there is not usually a big change from one day to the next. The memory impacts progress over time.

Physical Movement

One of the early symptoms of LBD is difficulty walking and decreased balance and ability to control movements. These symptoms are similar to Parkinson’s disease. Frequent falling is also common early in the disease.

With Alzheimer's, physical deterioration usually does not occur until the disease is advanced. With that said, because Alzheimer's typically affects older people, falling can occur due to frailty and the loss of orientation.

Some people with LBD display a flat affect, wherein their faces show very little emotion. This is another symptom present early in LBD and overlaps with Parkinson’s. While facial expressions often decrease with Alzheimer's, this usually doesn’t until the later stages.

Are LBD and Parkinson's the Same?

Some researchers contend that Parkinson's disease and Lewy body dementia are part of a larger spectrum of neurodegenerative disorders known as Lewy body disease (LBD).

Sleep Disturbances and Visual Hallucinations

People with LBD sometimes experience a condition known as REM sleep behavior disorder in which they will physically act out situations in their dreams. Some research suggests that REM sleep behavior disorder is an earlier predictor of LBD.

Another common LBD symptom is visual hallucinations, wherein people will see things that aren’t there. These hallucinations typically occur earlier in the course of LBD.

Hallucinations do occur with Alzheimer’s but are not as common. They also tend to occur in the later stages of the disease.

Similarly, REM sleep behavior disorder is not characteristic of Alzheimer's, although other types of sleep disturbances can occur.

Sensitivity to Antipsychotics

People with LBD have a high risk of serious side effects from antipsychotic medications. These are sometimes used as a last resort for people with behavioral symptoms of Alzheimer's.

Doing so with LBD, though less so Alzheimer's, can lead to a potentially life-threatening condition called neuroleptic malignant syndrome (NMS).

Symptoms of NMS include:

  • High fever
  • Muscle stiffness
  • Changes in mental state
  • Irregular heartbeat
  • Excessive sweating
  • Swings in blood pressure

Treatment for Lewy Body Disease

Where LBD and Alzheimer's vary significantly is in the ways they are treated. While some drugs, like cholinesterase inhibitors, can be used for both disorders, there are others that have proven to slow the progression of Alzheimer's only.

Lewy Body Dementia

There is no cure for LBD. Some symptoms can be managed with a treatment plan that may include medications, physical therapy, and counseling. The plan may also involve improving home safety and the everyday quality of life.

A combination of drugs called carbidopa-levodopa may be prescribed to improve LBD-related mobility problems, although they will not reverse symptoms.

Klonopin (clonazepam) may be prescribed to reduce symptoms of REM sleep behavior disorder, while melatonin can be taken to reduce insomnia.

Cholinesterase inhibitors are a class of drugs that may help treat some of the cognitive and behavioral symptoms of LBD and Alzheimer's, including impaired memory and awareness. Options include Razadyne (galantamine), Exelon (rivastigmine), and Aricept (donepezil).

Alzheimer's Disease

In addition to cholinesterase inhibitors, another class of drugs called N-methyl D-aspartate (NMDA) antagonists may be prescribed to help slow the progression of Alzheimer's. This includes the drug Namenda (memantine).

Amyloid monoclonal antibodies, like Lecanemab (Leqembi), may be prescribed to help treat cognitive symptoms by reducing amyloid plaques in the brain, slowing neurodegeneration and disease progression.

In June 2021, the Food and Drug Administration (FDA) approved Aduhelm for treating Alzheimer's disease. It was the first drug approved for this disease since 2003 and targets amyloid-beta. However, studies showed little or no benefit in slowing cognitive decline.

In January 2024, Biogen announced it would discontinue sales and clinical trials for the drug by November that year.

People with Alzheimer's can also benefit from physical therapy to help them stay mobile and improve their ability to perform daily tasks for as long as possible.

Prognosis for LBD

By and large, the prognosis of LBD is less favorable than Alzheimer's.

According to a 2019 study in PLoS One, the median life expectancy of people with LBD is between three and five years after the appearance of symptoms. This is far less than expected in people with Alzheimer's, although outcomes can vary. Death is often the result of respiratory failure due to damage to the part of the brain that regulates breathing.

By contrast, people with Alzheimer's survive for between four and 10 years after they are diagnosed. Improved Alzheimer's treatments account for part of the disparity, but it is likely that LBD is simply a more aggressive disorder. The main cause of death from Alzheimer's is secondary infections like pneumonia.

Lewy body dementia progresses faster and comes with a shorter life expectancy compared to Alzheimer's disease. Studies also show that Lewy body dementia leads to a lower quality of life compared to Alzheimer's, which includes a lower level of independence as well as other physical, mental, and social factors.

Summary

Lewy body dementia and Alzheimer's disease are the two most common forms of dementia that differ in a number of key ways. Both are linked to the abnormal buildup of proteins in the brains, but those involved with Lewy body dementia (LBD) are Lewy bodies and those involved with Alzheimer's are amyloids.

LBD also tends to progress faster and affects many different mental and physical domains, including thought, behavior, alertness, awareness, sleep, moods, and movement. Alzheimer's progresses somewhat slower and mainly affects memory, behavior, awareness, and language.

Because the causes and risk factors differ, the treatment of LBD and Alzheimer's also varies. Even so, LBD is frequently mistaken for Alzheimer's and, as such may be treated inappropriately. Knowing the differences can help you to better understand the diseases and speak with healthcare providers about them.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Esther Heerema, MSW
Esther Heerema, MSW, shares practical tips gained from working with hundreds of people whose lives are touched by Alzheimer's disease and other kinds of dementia.