Investigations and special investigations
(25-08-2005)
If dementia is found, it is necessary to determine the cause of the dementia and several investigations may be necessary such as blood tests and brain scans. The general practitioner can order a brain CAT scan and only specialists are allowed to order MRI (magnetic resonance imaging) scans.
A neuropsychological examination can also help determine what the underlying disease is.
For complex, atypical or rare diseases, it may be difficult to determine the cause of the dementia. In certain cases, it may be necessary to follow the course of the disease throughout a few years before the disease can be determined.
On dementianet, you can read more about how dementia is diagnosed. In special cases, other investigations may be necessary. The special examinations may be necessary if:
- the symptoms develop very quickly,
- the disease begins at an early age,
- there are special or uncharacteristic symptoms.
Blood Tests
During an examination for dementia, it is normal to take a series of blood tests to rule out other diseases such as low thyroid metabolism or reduced levels of Vitamin B12 and folate.
Electrocardiogram
An electrocardiogram (ECG) is normally done to rule out cardiac rhythm disorders or signs that the heart muscle is not getting enough oxygen. As certain types of anti-dementia medication may rarely affect cardiac rhythm, an ECG is often done prior to treatment. Discuss this with the doctor who is prescribing the medication.
Scanning of the brain structure (CAT or MR scanning)
Two types of scanning are used to examine brain structures:
CAT scanning
CAT scanning (computer axial tomography scanning) is an x-ray examination of the brain. The scanning normally takes 20-30 minutes. In a few cases it will be necessary to administer a contrast substance into a vein. Scanning is done for reasons such as ruling out the existence of a tumour, blood clot or other brain damage that could explain the symptoms.
MR scanning
MR scanning (magnetic resonance scanning) uses a magnetic field and radio waves to create the scanning images.
MR scanning is a more specialised examination. In many cases, MR scanning is not necessary and if it is it must be requested by a specialist.
Radiological appearances of the brain
The brain often looks normal during the early phases of Alzheimer's disease. A decrease in the size of the brain (called atrophy) is observed in the late phases. However, a decrease in the size of the brain can be observed in healthy elderly people without it being significant. In most instances where there is a decrease in the size of the brain, it is an expression of changes nor