Disease and ageing biomarker identification from multimodal magnetic resonance imaging

Examining how the brain changes over the lifetime provides valuable insights into brain development, ageing, and the markers of various diseases.

The primary focus was to understand how the brain matures and ages by examining age-related patterns in thousands of healthy peoples’ magnetic resonance images. These examinations were conducted at various spatial levels: from microstructures to analyses of the brain as a whole. Furthermore, we made use of the concept of brain age, an individual’s predicted or biological age based on machine learning models’ estimations. While brain age can serve as an indicator of general health, it can potentially also aid the identification of signs of diseases. Additionally, we investigated how different bio-psycho-social factors would associate with brain age, tested brain age and a new conceptualisation of brain age, and mapped associations of genetic risk for disease with the white matter development during ageing.

Generalisable patterns of brain maturation

We present spatial and temporal patterns of brain maturation showing multiple structural differences when comparing younger to older people. Especially, deep brain structures  such as the limbic system, which is known for its role in memory and various cognitive functions, were found to be age sensitive. These findings support previous studies which have shown promising results in treating neurodegenerative diseases using experimental treatment strategies such as electrical or ultrasound deep brain stimulation to the identified regions, such as fornix.

The search for biomarkers continues

Brain age is a promising marker of ageing and general health and allows one to identify abnormalities in brain development. Yet, the method is not specific to any disease. We show that applying brain age in the clinic is also still limited due to large variability in the individual level predictions, even when examining the same individuals over time. A proposed new conceptualisation of brain age assesses each hemisphere of the brain by itself, considering that the brain is highly asymmetrical. Other possibilities in the search for biomarkers include examining brain regions individually, and combining brain imaging with genetics which can add biological explanations to observed differences in brain characteristics.

Personalia

Max Korbmacher (born in 1993) has a master's degree in neuroscience and is a assistant professor and research fellow at the Department of Radiography at the Department of Health and Function, Western Norway University of Applied Sciences (HVL). The main supervisor for the dissertation has been Associate Professor Ivan Maximov.

Trial lecture

Thursdag 23th of May 2024, 09:15 in Aud. M005, campus Bergen.

Title: Magnetic resonance imaging – what it is and how it is used as a research tool.

Doctoral defense

Thursday 23th of May 202,  12:00 in Aud. M005, campus Bergen.

Title: Disease and ageing biomarker identification from multimodal magnetic resonance imaging

Committee

• Professor Valerij G. Kiselev, University Medical Center Freiburg, Tyskland (first opponent)
• Associate Professor Melanie Ganz, University of Copenhagen, Denmark (second opponent)
• Professor Birgitte Espehaug, HVL (committe leader)

Chair

Head of Department Gunnar Slettaløkken, HVL

Supervisors

• Associate Professor Ivan Maximov (main supervisor)
• Associate Professor Eli Nina Hølleland Eikefjord (co-supervisor)
• Professor em. Arvid Lundervold (co-supervisor)
• Professor Lars Tjelta Westlye, UiO (co-supervisor)