PET Scans for Dementia Diagnosis
Doctors seem to be having some success is determining what is causing dementia symptoms using PET (Brain Positron Emission Tomography) scans. Because dementia symptoms can be caused by a variety of things, and prescribing the right treatment depends on what's causing the dementia, knowing the cause of dementia symptoms is obviously important.
While PET Scans are still being used primarily by researchers, access to these tests is becoming easier as more university-based and dementia research clinics open. When your elder goes for a full diagnostic evaluation a PET scan may be one of the diagnostic tools they use.
PET scans are particuarly helpful in distinguishing between Alzheimer's Disease, frontotemporal dementia (FTD) and Lewy body dementia. FTD is marked by low activity in the front of the brain, while Alzheimer's Disease is marked by low activity in the back. Lewy body dementia involves degeneration of dopamine nerves in addition to the temporal (on the sides) and parietal (rear) lobes of the brain.
A PET scan will actually reveal the buildup of damaging beta-anyoid protein in the brain, which previously could only be confirmed by autopsy. We now know that these beta-amyloid proteins begin to build up long before dementia symptoms become obvious. Because a PET scan can catch this buildup before symptoms are debilitating, doctors can offer treatment and support earlier. While the treatment available today is not curative, it can often delay the development or the progression of symptoms, which can greatly improve someone's quality of life.
The PET scan process involves injecting a radioactive material into a vein. This material will collect in brain tissue. The PET machine detects energy given off by the radioactive substance and changes it into 3-dimensional pictures. The images are sent to a computer, where they are displayed on a monitor for the health care provider to read. The test is painless, but lengthy. It will usually take about an hour for the injected radioactive material to reach the brain before the scan can even begin.
A PET test will require a great deal of patient cooperation. Although the test itself is painless, and the machine is quiet, the test involves waiting for approximately an hour after the radioactive material has been injected, so the material can fully infiltrate the brain. The patient must then lie very still on a narrow table for another hour or more while surrounded by the tunnel-shaped machinery. This can be difficult for an alert and aware adult, especially if he or she has any difficulty with small, enclosed spaces. It is very difficult, if not impossible, for someone who is already experiencing moderate to severe dementia symptoms to lie immobile for so long.
For this reason, most PET scans are recommended for patients who may be experiencing memory problems, but who are not yet showing signs of full-blown dementia. The person with mild cognitive impairment who is worried about developing Alzheimer's Diseaseor one of the other dementias is a good candidate for a PET scan. This kind of patient should be able to handle the test with little difficulty and will benefit the most from treatment options if a problem is detected. If the test results are clear, it can be a great relief to someone who has been worrying.
If you doctor suggests a PET scan for someone with more advanced or agitated dementia, we recommend that you first have a serious talk about how the doctor's recommended treatment might change given all the possible results. This test can be tough and frightening for dementia patients because they aren't able to understand or to cooperate fully any more. Before you try to get a PET test done, be sure that the end result will be worth the trauma your elder may have to endure. If it's being recommended strictly for the satisfaction of "knowing," you might want to pass.
Photo Credit: Liz West