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Alzheimer's Disease Health Center

Dementia With Lewy Bodies

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Causes of Dementia With Lewy Bodies

We do not know why Lewy bodies form in the brain.

Symptoms of Dementia With Lewy Bodies

DLB symptoms vary from person to person. The one characteristic common to everyone with DLB is progressive loss of mental abilities that interferes with everyday activities. This may include the following:

  • Loss of recent memory
  • Inability to concentrate or pay attention
  • Difficulty thinking, reasoning, solving problems
  • Misperceptions of space and time

Mental function usually varies in DLB, getting better and worse over time. Although the sharpness of our mental function varies in everyone -- we all have our good moments and bad moments, or are "morning" persons or "evening" persons -- this fluctuation is especially dramatic in DLB. This is especially true of alertness and attention. A person with DLB typically has periods of being alert, coherent, and oriented that alternate with periods of being confused and less responsive. This usually is considered more characteristic of DLB than of other types of dementia. Other symptoms of DLB include:

  • Abnormal movements of Parkinson's disease (shuffling gait, tremor, muscle stiffness)
  • Visual hallucinations
  • Depression
  • Nonvisual hallucinations (hearing, smell, touch)
  • Delusions
  • Agitation
  • Unexplained fainting
  • Sensitivity to "neuroleptic" drugs given to control hallucinations and delusions

None of these symptoms are unique to DLB or definitively point to DLB as a diagnosis. In fact, people with DLB often are very difficult to distinguish from those with Alzheimer's disease. People with DLB, however, often develop both the cognitive symptoms of dementia (e.g., problems with memory and attention similar to those seen in Alzheimer's Disease) and motor symptoms (such as those seen in Parkinson's Disease) within one year of each other.

Exams and Tests for Dementia With Lewy Bodies

Dementia symptoms can have many different causes. Some underlying causes are reversible with treatment, others are not, but treatment is often still helpful. It is very important that all reversible causes be ruled out and that the type of dementia be diagnosed correctly, as treatment and outlook vary by type.

At this time, there is no foolproof way to confirm DLB in a living person. Definitive diagnosis of DLB is possible only after death. Examination of brain tissue at autopsy is the only way to confirm the presence of Lewy bodies. Certain chemical tests are applied to the tissue. One test detects alpha-synuclein, the major protein component of the Lewy bodies. Therefore, DLB is what medical professionals call a "clinical diagnosis." This means that the diagnosis is made on the basis of your symptoms, your medical history, your test results, and in some cases even your response to treatment. This method is based on detecting signs that may be very subtle and on the probabilities of your having a specific condition.

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