Q: What did we learn?
Dementia with mixed pathologies, most commonly with Alzheimer disease and small vessels disease, are frequent and may affect the presentation and progression of the symptoms.
A novel MRI technique to measure brain tissue integrity may help us better charactrize the extent of tissue damage in dementia with mixed pathologies.
The presence of multiple pathologies leads to another level of complexity in the care and management of people living with dementia.
Q: Why is this knowledge important?
Using a combination of imaging techniques and fluid biomarkers to evaluate the contribution of the different pathologies causing dementia can help us understand the interplay between these factors and identify ways to slow down or arrest the progression of disease.
Q: What are the next steps?
To confirm our findings, a larger scale multi-centre study will be needed. Further translational studies examining the interaction between vascular risk factors and Alzheimer pathogenesis will help us reduce the risk of future dementia incidences.
Over half a million people in Canada suffer from dementia today, costing the Canadian society over $15 billion dollars annually. Alzheimer disease and stroke are the first and second most common causes of dementia in the elderly. These two diseases often occur together in the brain, making it difficult to know which disease is contributing more to their cognitive decline. Recently, new tests on cerebral spinal fluid (CSF), magnetic resonance imaging (MRI), and positron emission tomography (PET), have begun to allow us to identify and quantify Alzheimer and stroke pathology in the living brain.
We hypothesize that patients with mixed dementia, that is, patients with both Alzheimer disease and small vessels cerebrovascular pathology causing their cognitive difficulties, will be affected more severely that those with a single type of pathology, either Alzheimer disease alone, or cerebrovascular disease alone. We also expect that there will be specific protein changes in the CSF (biomarkers) corresponding to each of the Alzheimer and vascular pathology. We will make use of new imaging and biomarker technologies to dissect how the two diseases interact to cause memory and cognitive problems in patients, and to understand how the two diseases together may amplify damages in the brain.
Understanding the interaction between Alzheimer disease and cerebrovascular disease will greatly advance dementia care, help us design better prevention strategies, and improve testing of new drugs under development.