Newer theories suggest waste is cleared from the brain by cerebrospinal fluid flushing through the brain. The accumulation of certain waste products within the brain is associated with Alzheimer’s disease. Therefore, the mechanism of which the brain gets rid of waste may be important to properly understand the progression of neurodegenerative diseases. In his thesis, Vinjeinvestigated theories of waste clearance from the brain using mathematical models.
The total volume of the cerebrospinal fluid around the brain is around 150 mL, and it is produced and absorbed at a rate of 500 mL per day. In addition to the slow, steady production, heart pulsations and respiration are drivers of cerebrospinal fluid flow. A few years ago, sleep was also proposed to cause a significant increase of cerebrospinal fluid flow into the brain, increasing waste clearance.
In this thesis, Vinjeconsiders all the different time scales on which the cerebrospinal fluid pulsates (i.e., steady flow, heart pulsations, and respiration). Vinje showsthat cerebrospinal fluid movement caused by heart pulsations may cause movement of the spinal cord in disease. Next, Vinje quantified the effect of respiration on fluid flow in the brain using the Navier-Stokes equation of fluid flow with pressure measurements as input data. In addition, he investigated other transport mechanisms (such as diffusion) and outflow pathways (such as the exchange between cerebrospinal fluid and blood).
Vinje concludes that fluid flow in the brain is necessary to explain tracer transportation to the brain as seen in MRI data, and that respiration may be an important driver for this flow.
The thesis is written within the field of scientific computing. The work has been conducted at Simula Research Laboratory.
Before the defense,Vegard Vinje presented histrial lectureIntegrated artificial intelligence and computational fluid dynamic approaches for patient-specific simulations - current state of the art and potential applications in the cerebrospinal fluid area.
The adjudication committee
- Senior Associate Scientist Diane de Zélicourt,University of Zürich
- Assistant Professor Olivier Balédent,Université de Picardie Jules Verne
- Associate ProfessorUlrik Skre Fjordholm,Universitetet i Oslo
Chair of the disputation
- ProfessorHans Brodersen,Matematisk Institutt, Universiteti Oslo
- Chief research scientist Marie Elisabeth Rognes,Simula Research Laboratory
- ProfessorYiannis Ventikos,University College London
- ProfessorKent-Andre Mardal,Matematisk Institutt, Universiteti Oslo