What Is Lewy Body Dementia?
Lewy body dementia (LBD) is a disease associated with abnormal deposits of a protein called alpha-synuclein in the brain. These deposits, called Lewy bodies, affect chemicals in the brain whose changes, in turn, can lead to problems with thinking, movement, behavior, and mood. Lewy body dementia is one of the most common causes of dementia.
Diagnosing LBD can be challenging. Early Lewy body dementia symptoms are often confused with similar symptoms found in other brain diseases like Alzheimer's or in psychiatric disorders like schizophrenia. Also, Lewy body dementia can occur alone or along with other brain disorders.
There are two diagnoses of LBD—dementia with Lewy bodies and Parkinson's disease dementia. The earliest signs differ but reflect the same biological changes in the brain. Over time, people with dementia with Lewy bodies or Parkinson's disease dementia may develop similar symptoms.
Who Is Affected by Lewy Body Dementia?
Lewy body dementia affects more than 1 million individuals in the United States. Lewy body dementia typically begins at age 50 or older, although sometimes younger people have it. LBD appears to affect slightly more men than women.
Lewy body dementia is a progressive disease, meaning symptoms start slowly and worsen over time. The disease lasts an average of 5 to 8 years from the time of diagnosis to death, but the time span can range from 2 to 20 years. How quickly symptoms develop and change varies greatly from person to person, depending on overall health, age, and severity of symptoms.
In the early stages of Lewy body dementia, symptoms can be mild, and people can function fairly normally. As the disease advances, people with LBD require more help due to a decline in thinking and movement abilities. In the later stages of the disease, they often depend entirely on others for assistance and care.
Some Lewy body dementia symptoms may respond to treatment for a period of time. Currently, there is no cure for the disease. Research is improving our understanding of this challenging condition, and advances in science may one day lead to better diagnosis, improved care, and new treatments.
What Are Lewy Bodies?
Lewy bodies are named for Dr. Friederich Lewy, a German neurologist. In 1912, he discovered abnormal protein deposits that disrupt the brain's normal functioning in people with Parkinson's disease. These abnormal deposits are now called "Lewy bodies."
Lewy bodies are made of a protein called alpha-synuclein. In the healthy brain, alpha-synuclein plays a number of important roles in neurons (nerve cells) in the brain, especially at synapses, where brain cells communicate with each other. In Lewy body dementia, alpha-synuclein forms into clumps inside neurons, starting in areas of the brain that control aspects of memory and movement. This process causes neurons to work less effectively and, eventually, to die. The activities of certain brain chemicals are also affected. The result is widespread damage to specific brain regions and a decline in abilities affected by those brain regions.
Lewy bodies affect several different brain regions in Lewy body dementia:
- The cerebral cortex, which controls many functions, including information processing, perception, thought, and language
- The limbic cortex, which plays a major role in emotions and behavior
- The hippocampus, which is essential to forming new memories
- The midbrain and basal ganglia, which are involved in movement
- The brain stem, which is important in regulating sleep and maintaining alertness
- Brain regions important in recognizing smells (olfactory pathways)
For More Information About Lewy Body Dementia
NIA Alzheimer’s and related Dementias Education and Referral (ADEAR) Center
The National Institute on Aging’s ADEAR Center offers information and free print publications about Alzheimer’s disease and related dementias for families, caregivers, and health professionals. ADEAR Center staff answer telephone, email, and written requests and make referrals to local and national resources.
Lewy Body Dementia Association
1-844-311-0587 (toll-free LBD Caregiver Link)
National Library of Medicine
Michael J. Fox Foundation for Parkinson's Research
Content reviewed: June 27, 2018