What Is Lewy Body Dementia?

Dementia with Lewy bodies (DLB) is one of the most common types of progressive dementia. The central feature of DLB is progressive cognitive decline combined with three additional defining features:

  1. Fluctuations in alertness and attention, such as:
    • frequent drowsiness,
    • lethargy,
    • lengthy periods of time spent staring into space, or
    • disorganized speech;
  2. Recurrent visual hallucinations; and
  3. Parkinsonian motor symptoms, such as rigidity and the loss of spontaneous movement. 

Lewy Body Dementia Symptoms

With DLB, you may also suffer from depression. Lewy bodies—accumulated bits of alpha-synuclein protein—build up in areas of the brain that control particular aspects of memory and motor control.

Researchers don’t know exactly why alpha-synuclein accumulates into Lewy bodies or how Lewy bodies cause the symptoms of DLB. They do know that the accumulation of alpha-synuclein is linked to:

The similarity of symptoms between DLB and Parkinson’s disease, and between DLB and Alzheimer’s disease, can often make it difficult for a doctor to make a definitive diagnosis.

In addition, specialists often find Lewy bodies in the brains of people with Parkinson's and Alzheimer’s diseases. This suggests that either DLB is related to these other causes of dementia or that you may be able to have both diseases at the same time.

DLB usually occurs in people with no known family history of the disease. Some individuals, in rare cases, have inherited Lewy body dementia.