In our laboratory, we aim to improve the quality of life by doing research within the ultimate objective of preserving brain health. The brain is an extremely sensitive organ which is crucial for human survival.
The research interests of Dre. Girouard are the study of the mechanisms underlying neurovascular coupling and cerebrovascular regulation in health and diseases especialy in the context of vascular dementia.
The main objective of her research is to find therapeutical targets to protect the brain in vascular diseases. To reach this objective, she uses various techniques from molecular biology to brain imaging in mice and humans.
Hypertension and the Brain
Hypertension is considered as an accelerator of brain aging and is a leading risk factor for cognitive dysfunctions, dementias and stroke. Ninety percent of the population will develop hypertension in their lifetime and prevalence of hypertension is predicted to substantially increase due to aging and of an increasingly sedentary population. Cognitive dysfunctions and dementia in hypertensive patients have been associated with accelerated brain aging, such as a faster shrinkage of white and grey matter, increased white matter hyperintensities, and impaired cerebrovascular reactivity.
To date, there is no convincing evidence that lowering blood pressure prevents dementia and there are conflicting data as to which antihypertensive drugs should be used for preventing dementia. Hypertension is a multifaceted risk factor with genetic, hormonal, metabolic, inflammatory and biophysical components. A better understanding of the mechanisms underlying accelerated cerebral aging in hypertension will help to develop preventive strategies for dementia and improve quality of life for older adults.
Neurovascular coupling is a control mechanism of the brain homeostasis by linking neuronal synaptic activity in blood flow in order to meet the needs for glucose and oxygen for neurons. Although this phenomenon has been investigated for over 100 years, the mechanisms by which an increase in synaptic activity results in vasodilation and dysfunctions remain poorly understood.
However, the fundamental study of neurovascular coupling is the basis of the principles of modern neuroimaging and understanding them could explain the dichotomies (positive / negative) observed in brain imaging and allow some neuropathological diagnosis. Furthermore, these functions can play a role in certain conditions such as aging, Alzheimer's disease, hypertension, and stroke.
Vascular and Alzheimer's Disease
It is now recognized that most cases of cognitive dysfunction and dementia in the elderly are associated with vascular disorders. However, very few studies have attempted to understand the relationship between vascular risk factors and dementia.
Using animal models of Alzheimer's disease and vascular dysfunction, we try to understand how these conditions interact to develop a comprehensive approach taking into account the hemodynamic and humoral components as well as those specific to Alzheimer's disease to treat dementias.
The objective is to examine therapeutic approaches acting primarily on vascular risk factors in order to preserve cognitive function.
We use a large array of techniques to create a powerful set of tools to explore our questions from the molecule to humans. Our perspective is that in vitro experiments are necessary to isolate parameters and offer a molecular resolution difficult to achieve in vivo. In vivo experiments provide a physiological and integrated perspective where we can take into account all elements of the neurovascular unit and the interactions between different systems within an organism. We also combine transgenic mice and pharmacological approaches to test therapeutic targets and molecular pathways. Finally, our non invasive research in humans offers a translational platform to test our hypothesis provided by fundamental research. In turn, data derived from clinical studies gives insights about experimental models to develop as well as therapeutical targets to study.