Bluewater Clinical Research Group, Dr. Anum Khalid
Imagine that we could diagnose Alzheimer’s disease before symptoms even began. Current research is focusing on developing treatments that target the disease in its earliest stages, prior to the onset of irreversible brain damage or mental decline occurring. Neuroimaging is regularly used for early detection of Alzheimer’s. Research continues to evolve on promising new and advanced brain imaging techniques. There are currently three types of imaging technologies used in Alzheimer’s research:
- Structural imaging: provides information about the shape, position or volume of brain tissue. Structural techniques include magnetic resonance imaging (MRI) and computed tomography (CT)
We know that the brain of an individual affected by Alzheimer’s progressively shrinks as the condition worsens. Structural imaging has revealed that shrinkage of specific brain areas such as the hippocampus may be an early sign of Alzheimer’s. As a result, we now have some degree of standardized values for brain volume loss over time that may be suggestive of the presence or progression of Alzheimer’s disease.
An assessment for Alzheimer’s disease may involve the utilization of structural imaging to define pre-existing tissue damage associated with neurodegeneration and to rule out other conditions that may cause symptoms similar to Alzheimer’s disease but require alternative treatment. Another advantage of structural imaging is its ability to reveal tumours, evidence of small or large strokes, damage from severe head trauma, or a buildup of fluid in the brain as well as check for underlying conditions that may be a contraindication to certain types of treatment.
- Functional imaging: reveals how well cells in various brain regions are working by showing how actively the cells use sugar or oxygen. Functional techniques include positron emission tomography (PET) and functional MRI (fMRI)
Our understanding of functional imaging suggests that individual’s with Alzheimer’s disease usually have reduced brain cell activity in certain regions. Studies with fluorodeoxyglucose (FDG)-positron emission tomography (PET) suggest that Alzheimer’s is frequently associated with lower use of glucose (sugar) in areas of the brain that play a critical role in memory, problem-solving and learning. It may be a reasonable test for individuals with a recent diagnosis of dementia and documented cognitive decline of at least six months.
- Molecular imaging: uses highly targeted radiotracers to detect cellular or chemical changes linked to specific diseases. Molecular imaging technologies include PET and fMRI.
Molecular imaging may help us to monitor disease progression and assess the effectiveness of next-generation disease-modifying treatments. Several molecular imaging compounds are currently being studied and a few have been approved for clinical use in order to detect either beta-amyloid or tau protein in the brain – both proteins that are implicated to play a role in the development of Alzheimer’s disease.
Your doctor will typically perform multiple tests in the office, order laboratory tests and do some of the imaging discussed above to make a formal diagnosis of Alzheimer’s disease. With continued research in advanced imaging techniques, we hope to be able to make the diagnosis at an earlier stage to prevent sequential cognitive decline.