Currently, an estimated 60 to 75% of diagnosed dementias are of the Alzheimer's and mixed (Alzheimer's and vascular dementia) type, 10 to 15% are Lewy body type, with the remaining types being of an entire spectrum of dementias, including frontotemporal lobar degeneration (Pick's disease), alcoholic dementia, pure vascular dementia, etc. Dementia with Lewy bodies tends to be under-recognized. Dementia with Lewy bodies is slightly more prevalent in men than women. DLB increases in prevalence with age; the mean age at presentation is 75 years.

Dementia with Lewy bodies affects about one million individuals in the United States.

Dementia with Lewy bodies (DLB) is a type of dementia that worsens over time. Additional symptoms may include fluctuations in alertness, visual hallucinations, slowness of movement, trouble walking, and rigidity. Excessive movement during sleep and mood changes such as depression are also common.

The cause is unknown. Typically, no family history of the disease exists among those affected. The underlying mechanism involves the buildup of Lewy bodies, clumps of alpha-synuclein protein in neurons. It is classified as a neurodegenerative disorder. A diagnosis may be suspected based on symptoms, with blood tests and medical imaging done to rule out other possible causes. The differential diagnosis includes Parkinson's and Alzheimer's.

At present there is no cure. Treatments are supportive and attempt to relieve some of the motor and psychological symptoms associated with the disease. Acetylcholinesterase inhibitors, such as donepezil, may provide some benefit. Some motor problems may improve with levodopa. Antipsychotics, even for hallucinations, should generally be avoided due to side effects.

DLB is the most common cause of dementia after Alzheimer's disease and vascular dementia. It typically begins after the age of 50. About 0.1% of those over 65 are affected. Men appear to be more commonly affected than women. In the late part of the disease, people may depend entirely on others for their care. Life expectancy following diagnosis is about eight years. The abnormal deposits that cause the disease were discovered in 1912 by Frederic Lewy.