Exams and Tests

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.

If you or a loved one is having dementia symptoms, your health care provider's job is to gather all the relevant information to make an accurate diagnosis. The first step is the medical interview. You will be asked questions about your symptoms and how they have developed over time, your medical problems now and in the past, medications, family medical problems, work and travel history, and habits and lifestyle. If you have trouble answering the questions, a family member or friend may be asked to fill in missing details. A thorough physical examination, including a mental status examination, will look for signs that might indicate the underlying cause of the dementia.

Neuropsychological testing

There is no definitive medical test that confirms dementia or DLB. The most accurate way to measure cognitive decline is through neuropsychological testing.

• The testing involves answering questions and performing tasks that have been carefully designed for this purpose. It is carried out by a specialist in this kind of testing. Neuropsychological testing assesses cognitive abilities such as memory, attention, orientation to time and place, use of language, and abilities to carry out various tasks and follow instructions.
  
  
• Reasoning, abstract thinking, and problem solving are tested.
  
  
• Neuropsychological testing gives a more accurate diagnosis of the problem and thus can help in treatment planning.
  
  
• The first test results are used as a baseline for measuring changes in cognitive abilities. The tests may be repeated periodically to see how well treatment is working and check for new problems.

Lab tests

There is no specific lab test for DLB. Lab tests of your blood may be needed to rule out certain causes of dementia, such as infection, metabolic disorders (such as thyroid imbalance), or medication effects. Basic tests may be done to check your overall level of general health.

Imaging studies

An imaging study of the brain is useful in determining the underlying cause of dementia. MRI is sometimes preferred to CT scan, because it affords greater detail of the brain. Although Lewy bodies cannot be detected on these images, other causes of dementia such as stroke can be ruled out. These images also can detect brain atrophy (shrinkage). The degree of atrophy can be useful in making a diagnosis.

Other tests

• Electroencephalography (EEG) measures brain waves. People with DLB sometimes have abnormal waves that can help in the diagnosis. This test is not used routinely, however.
  
  
• Lumbar puncture (spinal tap) with testing of spinal fluid may be used to rule out infection and certain other reversible disorders. Again, however, this test is not done routinely.