What is Lewy body dementia?

Lewy body dementia is a progressive dementia caused by abnormal deposits of a protein called alpha-synuclein, known as Lewy bodies, in the brain. The Alzheimer's Association says it covers two diagnoses: dementia with Lewy bodies and Parkinson's disease dementia. Core symptoms include changes in thinking that come and go, detailed visual hallucinations, acting out dreams during sleep, and slow movement, tremor or stiffness.

The National Institute on Aging says Lewy body dementia lasts an average of five to seven years from diagnosis to death, but the range runs from two to 20 years. How quickly symptoms develop and change varies greatly from person to person, depending on overall health, age and how severe the symptoms are. In the later stages, people may depend entirely on others for care.

Usually not. The National Institute on Aging says that having a family member with Lewy body dementia may increase a person's risk, but it is not typically considered a hereditary disease. A small percentage of families with dementia with Lewy bodies carry genetic variants that may be linked to risk. In most cases the cause is unknown, and no genetic test can predict who will develop it.

Memory loss is usually more prominent early in Alzheimer's, while early Lewy body dementia tends to bring hallucinations, movement problems, acting out dreams, and drops in blood pressure on standing that cause dizziness and falls. The Alzheimer's Association notes the two often overlap, because Lewy bodies commonly exist alongside Alzheimer's brain changes, which can make them hard to tell apart in the early stages.

Its symptoms can be treated, but the disease itself cannot be slowed or stopped. The Alzheimer's Association says cholinesterase inhibitors may help some symptoms and antidepressants can treat depression. It warns that antipsychotic drugs should be used with extreme caution, because they may cause serious side effects in as many as 50 percent of people with Lewy body dementia. A doctor should guide every medication decision.