MRI exploits the properties of water within our brains to produce images, which can be done in different ways depending on what aspect of brain health is of most interest. In her project, Dr Watt is using multiple different types of MRI sequences, which assess the anatomical structures of the brain. Using these sequences together gives a more detailed image of a person’s brain structure.
This approach can measure visible brain injury, which can occur for various reasons, and is called the Brain Health Index (BHI). The BHI scores brain health by assessing voxels (similar to pixels in a photograph) within the brain scan and characterising these as healthy or unhealthy. Over the whole brain, this then gives a figure which provides an indication of the brain’s overall structural health.
Dr Watt is initially doing this with MRI scans from the UK Biobank, one of the largest brain imaging studies in the world. She said: ‘By analysing the brains of these healthy volunteers, I hope to identify normal measures of a healthy brain. To understand what happens in the brains of people with dementia, we must first understand how the findings of the Brain Health Index vary within healthy people, which we can then compare to people with various types of dementia.’
Once Dr Watt has calculated the brain health index of the healthy brains from the UK Biobank, she will repeat the process – this time analysing brain scans from the European Prevention of Alzheimer's Dementia (EPAD) Longitudinal Cohort Study.
The final stage of the project will be to calculate the brain health index of brain scans taken by the NHS of people with memory problems. Analysing these images will be more challenging because these scans were taken under less controlled conditions than in research settings, and with an added time pressure. This means it may not be feasible to calculate the BHI from these scans.
However, if Dr Watt is successful in yielding BHI from the NHS scans, it may be an incredibly useful resource, allowing researchers and clinicians to see changes in a person’s brain structure over time – and how this relates to their cognitive health. Subsequently, this may also be helpful for research projects measuring the effectiveness of future interventions which aim to slow, halt or reverse structural brain ageing.
Dr Watt said: ‘Ideally, we would hope to see differences between the scans from UK Biobank and EPAD, and the clinical patients within the NHS, to establish any differences which are due to clinical diagnostic status. However, we must also be aware that everyone’s brains are unique and that these individual differences may play a role in our findings.’
Dr Watt is currently working on the first step of this project within the UK Biobank. At this stage, she is hoping to establish normative BHI values so that the BHI may be used by individuals beyond her own research group.
Dr Watt works under the supervision of Dr Terry Quinn, who is a DPUK Project Lead within the Vascular Health theme of our Experimental Medicine Incubator. Keep an eye on the news section of the DPUK website for updates about her project.