Dementia with Lewy bodies (DLB) is a brain disease that causes dementia and other symptoms. It is linked to protein deposits called Lewy bodies in brain cells.

With DLB, the dementia symptoms start early in the disease and interfere with daily life. They can include problems with attention, time management, problem solving, learning, and memory. People may get lost in familiar places, have a hard time judging distances, and be more impulsive.

Someone with this condition will also have two of the following symptoms:

• Cognitive fluctuations. These are periods of normal function broken up by times of confusion or not being able to think clearly. People may be alert and then suddenly act strangely or "zone out." These may last between several seconds and several days.
• Visual hallucinations. These involve seeing things that aren't there. They may be well formed and detailed.
• Rapid eye movement (REM) sleep behaviour disorder. People with this condition act out their dreams while they sleep.
• Parkinsonism. These symptoms are shared with Parkinson's disease. They may include slow, stiff movements; tremor; and trouble walking.

Other symptoms may include falling, being sensitive to certain medicines, passing out, severe sleepiness, and loss of smell. Most symptoms get worse over time.