Lewy body dementia is a progressive form of dementia. This means that it starts slowly and gradually gets worse over time rather than appearing suddenly. Most people who have some progressive form of dementia will begin to have symptoms that appear to be normal everyday problems that most people experience from time to time. This might be not being able to remember a name or word, mild problems misplacing or forgetting where one put items, etc. These issues get worse and worse over time until the person begins to experience serious problems in their everyday routine.
The major brain change associated in people with Lewy body dementia is the development of Lewy bodies. These are tangled bodies of protein in the neurons (nerve cells in the brain). At the time of this writing, there is no objective way to determine the formation of a significant amount of Lewy bodies in a person's brain except by analyzing brain tissue after the person has died. Lewy bodies are also present in the brains of people that do not have dementia, people with Alzheimer's disease, people with Parkinson's, and with other forms of brain diseases/disorders.
This section will briefly outline some of the symptoms of Lewy body dementia and how it may be different from other forms of dementia. The next section will discuss the actual diagnostic criteria used by the DSM-5 and other tests/procedures. It should be noted that at the time of this writing the diagnosis of Lewy body dementia or many other forms of dementia such as Alzheimer's disease are clinical diagnosis. A clinical diagnosis is a doctor's best guess or best determination as to the cause of the person's disorder. This guess is based on the types of symptoms that the person presents with and test results. The only way to really know if a person has Lewy body dementia is to analyze a sample of their brain tissue after they have died. However, these best guesses made by experienced doctors are generally extremely accurate. The accurate diagnosis of any form of dementia is dependent on recognizing the problems early. Different forms of dementia are easier to diagnose when the person is assessed early in the course of their problems. As the person's problems advance, the different types of dementia begin to appear more alike than they do different.
Some symptoms that may suggest that a person has Lewy body dementia include:
- The person has significant changes in their cognition (thinking and reasoning) over time (not a sudden change). The memory loss that occurs in people with this disorder is similar to the memory loss that occurs in people with Alzheimer's disease. However, it often is not as severe.
- The person has days where they are confused and then other days when they are not confused. Problems with changes in confusion and even their awareness can vary from day to day or one time of day to another time of day. Often people have varying problems with attention that accompany periods of confusion.
- People with this disorder often have more problems with their visual spatial skills than people with Alzheimer's disease or Parkinson's disease. This could involve the person having difficulty recognizing people or determining the relationships of objects and their environment.
- The person often displays symptoms like someone with Parkinson's disease would have. This includes rigid muscles, a hunched posture, and problems with balance.
- Some people have visual hallucinations (seeing things that are not there) or have delusions (very rigid beliefs that are not true).
- People with this disorder often act out their dreams in their sleep. This acting out of dreams is often very violent and aggressive. It is termed as a rapid eye movement sleep disorder (REM sleep disorder) because most of our dreams happen in the REM sleep periods.
- Other problems with the autonomic or automatic nervous system that can include a decrease in a person's blood pressure when they stand from a sitting or lying position that causes dizziness and falls or problems holding their urine.
Because Lewy body dementia resembles Alzheimer's disease doctors often attempt to distinguish Alzheimer's disease from Lewy body dementia from the following:
- Memory loss is much more severe in Alzheimer's disease, especially in the early stages.
- Movement problems are more likely to be present in neurocognitive disorder with Lewy bodies than in Alzheimer's disease.
- Problems with hallucinations and visual spatial skills (identifying people) are more common in the early stages of neurocognitive disorder with Lewy bodies.
- REM sleep disorder is more common in early neurocognitive disorder with Lewy bodies than in Alzheimer's disease.
- The issues with the autonomic nervous system are more common in early Lewy body dementia and Alzheimer's disease.
Symptoms that differ in Lewy body disease from Parkinson's disease may include memory issues that appear earlier in Lewy body dementia than they do in Parkinson's disease. People with Parkinson's disease who develop dementia typically have more advanced Parkinson's symptoms. This includes movement problems, problems expressing emotion, tremors in the hands (a type of shakiness).
Doctors are more likely to diagnose Lewy body dementia when:
- The symptoms associated with Lewy body dementia appear first.
- When the symptoms of dementia (memory loss) and problems with movement are present at the same time that the doctor diagnoses the person's problems.
- When the dementia problems appear within one year after movement problems have been diagnosed.
If the problems with dementia appear a year or more after the movement problems have been diagnosed the person is more likely to be given a diagnosis of Parkinson's disease.