Alzheimers Home > Laboratory Procedures Used to Diagnose Dementia
Other Brain Scan Tests
Several other types of brain scans allow researchers to watch the brain as it functions. These scans, called functional brain imaging, are not often used as diagnostic tools, but they are important in research and they may ultimately help identify people with dementia earlier than is currently possible. Types of functional brain scans include:
- Functional MRI (fMRI) -- fMRI uses radio waves and a strong magnetic field to measure the metabolic changes that take place in active parts of the brain.
- Single photon-emission computed tomography (SPECT) -- SPECT shows the distribution of blood in the brain, which generally increases with brain activity.
- Positron emission tomography (PET) -- PET scans can detect changes in glucose metabolism, oxygen metabolism, and blood flow, all of which can reveal abnormalities of brain function.
- Magnetoencephalography (MEG) -- MEG can show the electromagnetic fields produced by the brain's neuronal activity.
Doctors may use a variety of laboratory tests to help diagnose dementia or rule out other conditions, such as kidney failure, which can contribute to symptoms. A partial list of these tests includes:
- A complete blood count (CBC)
- Blood glucose test, which measures sugar levels in the blood
- Drug and alcohol tests (toxicology screen)
- Cerebrospinal fluid analysis (to rule out specific infections that can affect the brain)
- Analysis of thyroid and thyroid-stimulating hormone levels.
A doctor will order only the tests that he or she feels are necessary to improve the accuracy of a diagnosis.