Dementia with Lewy bodies

What is dementia with Lewy bodies?

Dementia with Lewy bodies is a type of Lewy body dementia. The other type is Parkinson’s disease dementia. Lewy body dementia is the umbrella term which describes the two types. Visit the section dedicated to Lewy body dementia to learn more.

What causes dementia with Lewy bodies?

Dementia with Lewy bodies is caused by deposits of an abnormal protein (called Lewy bodies) that build up inside nerve cells in the brain. The protein is called alpha-synuclein and the protein clumps damage the way nerve cells work and communicate.


Dementia with Lewy bodies symptoms fall into five categories:


  • Dementia is a primary symptom of Lewy body dementia i.e. a decline in the cognitive (thinking) abilities that interferes with everyday life.
  • Changes or “fluctuations” in cognition (awareness and concentration). The person will swing from a state of alertness to appearing drowsy and/or confused, as well as reduced attention span.
  • Recurrent visual hallucinations, such as seeing shapes, colours, people, or animals that aren’t there or conversing with deceased loved ones.
  • More trouble with complex mental activities, such as multitasking, problem solving, and analytical thinking.
  • Problems with visual and spatial perception, such as judging and navigating distances.

Note: Unlike other types of dementia, memory problems may not be evident at first but often arise
as the disease progresses.

Motor problems

People with Lewy body dementia also experience motor problems (the part of the nervous system involved with movement) and experience symptoms similar to Parkinson’s including:

  • Slow movement / shuffling walk / stiff limbs / tremors and shaking / balance problems / difficulty swallowing / weak voice.

Autonomic problems

They also experience fluctuations in autonomic processes (the part of the nervous system that regulates bodily functions) including:

  • Blood pressure / body temperature / urinary difficulties / constipation / dizziness / frequent falls and fainting / impaired sense of smell / runny nose.

Sleep disorders

Sleep problems include:

  • REM sleep behaviour disorder – a disorder where you physically move limbs and talk while sleeping.
  • Insomnia.
  • Excessive daytime sleeping.

Behaviour & mood

Changes in behaviour and mood (psychiatric disturbances) often occur with Lewy body dementia including:

  • Depression / apathy / anxiety / agitation / delusions / paranoia.

Life expectancy

The average life expectancy for people with dementia with Lewy bodies after the onset of symptoms is 5 to 8 years.

Additional Information

What is dementia with Lewy bodies
People with a Lewy body dementia may have a severe sensitivity to anti-psychotic drugs.