Dementia with Lewy Bodies (DLB) is a progressive degenerative disease or syndrome of the brain. It shares symptoms - and sometimes overlaps - with several diseases, especially with two common diseases of older adults, Alzheimer’s and Parkinson’s.
Persons who develop DLB have behavioral and memory symptoms of dementia like those of Alzheimer’s disease and, to varying extents, the physical, motor system symptoms seen in Parkinson’s. However, the mental symptoms of a person with DLB might fluctuate frequently, motor symptoms are milder than for Parkinson’s disease, and DLB patients usually have vivid visual hallucinations.
DLB is named after smooth round protein lumps, called Lewy bodies, that are found in the nerve cells of affected brains. Lewy bodies are often present in the nuclei (nerve cells) of brains afflicted with a variety of disorders. In DLB, the Lewy bodies are found throughout the outer layer of the brain (the cerebral cortex) and deep inside the midbrain or brainstem. These “abnormal protein structures” were first described in 1912 by Fredrich Heinrich Lewy, M. D., a contemporary of Alois Alzheimer who first identified the more common form of dementia that bears his name.
Because Lewy bodies are also often found in the brains of those diagnosed with Alzheimer’s, Parkinson’s, Down Syndrome and other disorders, researchers agreed in 1995 to use the term “Dementia with Lewy Bodies” to describe both a single disease (sometimes called “pure DLB”) and a spectrum of disorders with similar or related pathology.
It is believed that DLB, as a defined disease process, accounts for as many as 20% of the seven million cases of dementia in the United States and for as much as one-third of dementing illness in elderly Americans. This makes DLB the second most common form of dementia after Alzheimer’s.
Also see: NINDS Dementia With Lewy Bodies Information Page