What are Lewy Bodies?

Dementia comes in many forms. The most common is Alzheimer’s disease, which accounts for 60 to 80 percent of cases, but there are many other subtypes. Lewy body dementia (LBD) is the second most common type of progressive dementia, accounting for 5 to 10 percent of cases and affecting 1.4 million people in the US. LBD is an umbrella term for any dementia associated with the presence of Lewy bodies, including dementia with Lewy bodies (DLB) and Parkinson’s disease dementia (PDD).

What are Lewy Bodies?

Lewy bodies are abnormal deposits of a protein called alpha-synuclein in the brain. The formation of Lewy bodies is associated with the loss of certain neurons that produce two types of neurotransmitters, or chemicals that act as messengers between brain cells.

The first of these chemicals is acetylcholine, which is critical for memory and learning. The other chemical, dopamine, plays a significant role in how humans feel pleasure and affects the ability to think and plan. The reduction in acetylcholine and dopamine can lead to problems with thinking, memory, movement, behavior, and mood.

Lewy bodies are not the only defining factor of LBD. People with this protein buildup in their brains may also have the plaque and tangles associated with Alzheimer’s disease.

What Causes Lewy Bodies to Form?

Scientists do not know the exact reason behind Lewy body dementia, but ongoing research aims to learn more about the genetics and risk factors behind it. The current known risk factors for Lewy bodies in the brain include:

  • Age: Symptoms typically appear at age 50 or older, though sometimes younger people can develop LBD.
  • Gender: Men are slightly more likely to be diagnosed with Lewy body dementia than women.
  • Health: The presence of Parkinson’s disease or REM sleep behavior disorder is linked to a higher risk of LBD.
  • Family history: Having a family member with Lewy body dementia may increase a person’s risk, though this condition is not considered a genetic disease. Variants in several genes are also associated with an increased risk, but most cases of LBD have no known cause.

The Lewy Body Dementia Association is dedicated to raising awareness of LBD. Feel free to explore the many resources on our website such as Is It Lewy?, Facing LBD Together, and the NIH Booklet on LBD. Then, to learn more, please contact us through our website, sign up for our email newsletter, or connect with us on Facebook and Twitter.