What To Know About Lewy Body Dementia

Following Alzheimer's disease and Vascular dementia, Lewy Body dementia is the third most common form of dementia, affecting an estimated 1.4 million people in the U.S. This condition involves the buildup of clumps of proteins — called Lewy bodies — in the brain’s nerve cells. These abnormal proteins damage nerve cells and negatively impact dopamine, a neurotransmitter that is critical for controlling movement.

Lewy Body dementia is named after Dr. Friedrich Lewy, a German neurologist who first described the abnormal protein deposits found in the brains of people with the disease, in 1912, while working in the laboratory of Dr. Alois Alzheimer.

Lewy body deposits affect brain regions involved in thinking, memory and movement. There are two forms of Lewy Body dementia that cause cognitive symptoms — dementia with Lewy bodies and Parkinson's disease dementia.

Lewy body dementia causes a decline in mental abilities that gradually gets worse over time. People with Lewy Body dementia might see things that aren't there, known as visual hallucinations. They also may have changes in alertness and attention.

People with Lewy body dementia commonly have symptoms of Parkinson's disease. These symptoms might include rigid muscles, slow movement, trouble walking and tremors.

Symptoms

The most common features of Lewy Body dementia are:

- Progressive cognitive impairment leading eventually to full-blown dementia.

- Visual hallucinations - Seeing things that aren't there (hallucinations) might be one of the first symptoms of Lewy body dementia. This symptom often occurs regularly and may include seeing shapes, animals or people that aren't there. Hallucinations involving sounds, smells or touch are possible.

- Movement symptoms - Signs of Parkinson's disease may occur. These symptoms include slowed movement, rigid muscles, tremors or a shuffling walk. This can cause the person to fall.

- Poor regulation of body functions - The part of the nervous system that controls automatic functions is called the autonomic nervous system. Lewy body dementia can affect how well the autonomic nervous system controls blood pressure, heart rate, sweating and digestion. This can result in sudden drops in blood pressure upon standing, dizziness, falls, loss of bladder control and bowel issues such as constipation.

- Cognitive changes - People with Lewy body dementia might have changes in thinking that are similar to symptoms of Alzheimer's disease. These symptoms may include confusion, poor attention, visual-spatial problems and memory loss.

- Trouble with sleep - People with Lewy body dementia can have rapid eye movement, also known as REM sleep behavior disorder. This disorder causes people to physically act out their dreams while asleep. People with REM sleep behavior disorder may punch, kick, yell or scream while sleeping.

- Varying attention - Episodes of drowsiness, long periods of staring into space, long naps during the day or disorganized speech are possible.

- Depression or apathy - People with Lewy body dementia might develop depression or lose motivation. Sensitivity or over-reaction to antipsychotic drugs (aka neuroleptics) is also common.

Cause and Pathology

The cause of Lewy Body dementia is unknown. The condition is caused by the buildup of abnormal proteins which damage the brain’s nerve cells. The Lewy body overwhelms the nerve cell’s normal biological functions and causes it to die.

Risk Factors

A few factors seem to increase the risk of developing Lewy Body dementia, including:

- Age - People older than 60 have a higher risk of getting the disease.

- Gender - Lewy Body dementia affects more men than women.

- Family history - Those who have a family member with Lewy Body dementia or Parkinson's disease are at greater risk.

Complications

Lewy Body dementia is progressive. This means it gradually gets worse over time. A hallmark sign of Lewy Body Dementia is varying levels of cognition, meaning there will be good days and then bad days.

Diagnosis

Lewy Body dementia can be difficult to diagnose because its early symptoms can resemble those of other conditions, like Alzheimer's disease or Parkinson's disease. A diagnosis often requires a team of specialists, including neurologists, geriatric psychiatrists and neuropsychologists. There is no single definitive test for Lewy Body dementia. Diagnosis is often based on a combination of clinical symptoms, cognitive testing and imaging.

Progression and Treatment

Lewy Body dementia is a progressive disease, and its progression varies from person to person. There is no cure yet, but treatments exist that focus on managing symptoms and improving quality of life.

Medications like cholinesterase inhibitors and certain antipsychotics may be used to address cognitive and behavioral symptoms.

Important Considerations

Symptoms can vary greatly from person to person, and the rate of progression can also differ. Support and resources are available for individuals with Lewy Body dementia and their families, including healthcare professionals, support groups and organizations such as the Lewy Body Dementia Association.

How does Lewy Body dementia differ from Alzheimer's disease?

Lewy Body dementia and Alzheimer's disease are both forms of dementia, but they differ in their primary symptoms, progression and underlying causes.

- Lewy Body dementia is characterized by fluctuating cognition, visual hallucinations and Parkinsonism-like motor symptoms, while Alzheimer's primarily impacts memory and learning.

- Lewy Body dementia affects frontal and subcortical brain regions, impacting executive function, visuospatial skills, and attention. Alzheimer's primarily affects temporoparietal cortical regions, impacting memory and language.

- Lewy Body dementia can progress rapidly, with a faster decline in cognitive abilities compared to Alzheimer's, although progression can vary significantly between individuals. Alzheimer's typically progresses gradually over time, with a slower, more predictable decline.

- Lewy Body dementia is caused by the abnormal buildup of proteins called Lewy bodies in the brain. Alzheimer's is characterized by the buildup of amyloid plaques and tau tangles in the brain.

- Regarding treatment, Lewy Body dementia medications such as cholinesterase inhibitors can be helpful, but antipsychotics can be dangerous and should be used cautiously. Treatment for Alzheimer's focuses on managing symptoms, preserving mental function and potentially slowing disease progression with medications like aducanumab, cognitive training and other therapies.

In essence, while both Lewy Body dementia and Alzheimer's involve cognitive decline, Lewy Body presents with a unique constellation of symptoms including fluctuating cognition, visual hallucinations, and Parkinsonism, while Alzheimer's is more strongly defined by memory loss.

Research

In 2013, the National Institutes of Health organized a summit that resulted in the first national research strategy for Lewy Body dementia. Updated in 2016, research priorities include:

- Developing new drugs for clinical trials

- Establishing longitudinal studies culminating in autopsy studies to improve diagnosis

- Developing a better understanding of the disease mechanisms through brain mapping and genetics

- Identifying validated biological and imaging biomarkers to detect disease presence, measure progression and advance the development of safe and effective therapies

This content is for informational purposes only. For medical advice or diagnosis, consult a medical professional.

Sources: Mayo Clinic and Lewy Body Dementia Association