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Lewy body dementia is a progressive, degenerative brain disease. It’s the third most common type of dementia, after Alzheimer’s and vascular dementia. This report is from DailyCaring.

It can be confusing because some symptoms are similar to those found in Alzheimer’s, but loss of short-term memory isn’t common. It can also be tough to diagnose because some of the symptoms are similar to Parkinson’s disease.

So, how is it different from Alzheimer’s and Parkinson’s, and what are the five main symptoms of the disease?

What is Lewy body dementia?

It’s called Lewy body dementia because the disease is associated with clumps of protein found in the brain called Lewy bodies.

When they build up, they cause problems with the way the brain works, including memory, movement, thinking skills, mood, and behaviour.

There are two forms of Lewy body, dementia with Lewy bodies and Parkinson’s disease dementia.

In dementia with Lewy bodies, the first symptoms are like the memory disorders seen in Alzheimer’s. Later, the person will develop movement problems and other Lewy body symptoms.

In Parkinson’s disease dementia, the person first develops a movement disorder that looks like Parkinson’s, but later develops dementia symptoms. Their physical symptoms may also be milder than in typical Parkinson’s.

How is Lewy body dementia different from Parkinson’s or Alzheimer’s?

Lewy body dementia is similar to and often confused with Parkinson’s or Alzheimer’s. But there are some differences in the symptoms and when those symptoms happen.

Lewy body may not cause short-term memory loss that happens with Alzheimer’s. In Lewy body, problems with thinking, alertness, and paying attention will come and go.

A sign that your older adult could have Lewy body rather than another dementia is if they have symptoms of cognitive decline without the typical short-term memory problems.

For example, Lewy body often causes hallucinations, especially in the first few years. With Alzheimer’s, hallucinations usually don’t show up until the later stages.

People with Lewy body also have REM sleep behaviour disorder, which causes them to act out their dreams and make violent movements while asleep. This is not common in Alzheimer’s.

Both Lewy body and Parkinson’s cause problems with movement, but Parkinson’s doesn’t cause problems with thinking and memory until the later stages of the disease – and sometimes it doesn’t happen at all. With Lewy body, the cognitive problems start much sooner.

Because of these differences, the treatments and medications used for Lewy body dementia are not always the same as the ones used to treat Parkinson’s or Alzheimer’s.

5 Main symptoms of Lewy body dementia

There are five groups of symptoms that are common in Lewy body dementia. They will get worse over time, usually over several years.

  1. Cognitive impairment

Extreme swings between being alert and being confused or drowsy – episodes are unpredictable and could last a few seconds to several hours.

  • Reduced attention span
  • Difficulty with planning, decision-making, organisation
  • Problems with visual perception (judging and navigating distances) – often causing falls or getting lost in familiar places
  • Increased trouble with the tasks of daily livin
  1. Visual hallucinations

Repeated visual hallucinations or delusions are also common – like seeing shapes, colours, people, or animals that aren’t there. They may also have conversations with people who are deceased.

  1. Problems with movement
  • Slow movement
  • Shuffling walk or abnormal gait
  • Stiff limbs
  • Tremors
  • Lack of facial expression
  1. Sleep disturbances
  • Insomnia
  • Daytime sleepiness
  • REM sleep behaviour disorder – acting out dreams while asleep: physically moving, sleep talking, screaming, hitting, or even getting up and engaging in daytime activities
  1. Fluctuations in autonomic processes

Lewy body may also cause problems with bodily functions that are automatic, including blood pressure, body temperature, urination, constipation, and swallowing.

Life expectancy with Lewy body

The average person usually lives five to seven years after the disease starts and they usually die of pneumonia or other illness. Unlike other dementias, Lewy body doesn’t follow a pattern of stages. The disease will continue to get worse over time, but the rate of decline is different in each person.


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