Overview

Lewy body dementia, also known as LBD, is the second most common type of dementia after Alzheimer's disease. Protein deposits called Lewy bodies develop in nerve cells in the brain. The protein deposits affect brain regions involved in thinking, memory and movement. There are two forms of LBD that cause cognitive symptoms — dementia with Lewy bodies and Parkinson's disease dementia.

Lewy body dementia causes a decline in mental abilities that gradually gets worse over time. People with LBD might see things that aren't there, known as visual hallucinations. They also may have changes in alertness and attention.

People with Lewy body dementia commonly have symptoms of Parkinson's disease. These symptoms might include rigid muscles, slow movement, trouble walking and tremors.

Symptoms

Lewy body dementia symptoms can include:

  • Visual hallucinations. Seeing things that aren't there, known as hallucinations, might be one of the first symptoms of Lewy body dementia. This symptom often occurs regularly and may include seeing shapes, animals or people that aren't there. Hallucinations involving sounds, smells or touch are possible.
  • Movement symptoms. Signs of Parkinson's disease may occur. These symptoms include slowed movement, rigid muscles, tremor or a shuffling walk. This can cause the person to fall.
  • Poor regulation of body functions. The part of the nervous system that controls automatic functions is called the autonomic nervous system. Lewy body dementia can affect how well the autonomic nervous system controls blood pressure, heart rate, sweating and digestion. This can result in sudden drops in blood pressure upon standing, dizziness, falls, loss of bladder control and bowel issues such as constipation.
  • Cognitive changes. People with Lewy body dementia might have changes in thinking that are similar to symptoms of Alzheimer's disease. These symptoms may include confusion, poor attention, visual-spatial problems and memory loss.
  • Trouble with sleep. People with Lewy body dementia can have rapid eye movement, also known as REM sleep behavior disorder. This disorder causes people to physically act out their dreams while asleep. People with REM sleep behavior disorder may punch, kick, yell or scream while sleeping.
  • Varying attention. Episodes of drowsiness, long periods of staring into space, long naps during the day or disorganized speech are possible.
  • Depression or apathy. People with Lewy body dementia might develop depression or lose motivation.

Causes

In people with Lewy body dementia, there's a buildup of proteins known as Lewy bodies. This protein also is associated with Parkinson's disease. People who have Lewy bodies in their brains also can have the plaques and tangles associated with Alzheimer's disease.

Risk factors

A few factors seem to increase the risk of developing Lewy body dementia, including:

  • Age. People older than 60 have a higher risk of getting the disease.
  • Sex. Lewy body dementia affects more men than women.
  • Family history. Those who have a family member with Lewy body dementia or Parkinson's disease are at greater risk.

Complications

Lewy body dementia is progressive. This means it gradually gets worse over time. As symptoms get worse, the disease can lead to:

  • Worsening dementia.
  • Aggressive behavior.
  • Depression.
  • Increased risk of falling and injury.
  • Worsening of movement symptoms, such as tremors.
  • Death, on average about 7 to 8 years after symptoms start.
By Mayo Clinic Staff