Opinion: use of MEG may help identify those at risk of developing dementia, allow earlier disease management and improve quality of life

Developing an effective cure for dementia has been a long-standing challenge for researchers. Typically, treatment for dementia addresses the symptoms of the disease rather than addressing the cause itself. Current treatment also doesn't have significant effect on how the disease advances. Therefore, it’s critical that dementia is diagnosed earlier, which can lead to earlier management of the condition and delay of onset. In turn, this could reduce healthcare costs by, for example, more than £5 billion in the UK.

Since dementia has a gradual onset with a long timescale, few or no symptoms are observed during the initial stages. This makes early diagnosis even more problematic. Presently, clinicians employ a wide range of diagnostic tests including analysing blood samples, mental assessment tests, detailed medical history, and if required, a brain MRI/PET/CT scan.

With the currently available diagnostic techniques, an official dementia diagnosis can take up to months or even a few years depending on the severity of the symptoms. Although the diagnosis rates of dementia have increased in the past few years, it is estimated that about 20% of the cases are misdiagnosed. At present, the only definitive way to confirm dementia is to posthumously analyse brain tissue samples under a microscope.

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From RTÉ Radio 1's Today With Sean O'Rourke, an interview with Dr Sabina Brennan about practical ways to promote long-term brain health, the relationship between chronic stress and dementia and ageing and sleep patterns

Studies have shown that signalling dysfunction in the brain occurs before structural damage is observed in cases of dementia. This is where an exciting and powerful technology; Magnetoencephalography (MEG) comes into play. This is a functional neuroimaging technique that maps brain activity using extremely sensitive magnetometers called SQUIDs (superconducting quantum unit interference devices).

At any given time, our brains generate electrical impulses, whether we are watching a movie, playing a sport or even sleeping. These electrical signals in turn generate faint magnetic fields on the order of a few femtoteslas (unit for measuring magnetic field) that can be measured by the SQUIDs. This weak magnetic field of the brain is about a trillion times smaller than that of a small bar magnet. 

The MEG machine primarily consists of more than 300 SQUID sensors mounted in a helmet, which sits inside a magnetically shielded room that helps reduce background noise. The large number of sensors offer enhanced spatial resolution, allowing better source localisation of brain signals. Additionally, MEG also offers high temporal resolution of milliseconds, which cannot be achieved by other functional imaging techniques such as functional MRI.

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From RTÉ Radio 1's Let's Talk Dementia, Fionnuala Sweeney talks to Professor Brian Lawlor, chairperson of the Understand Together Campaign Steering Committee, about the importance of exercise in improving brain health

What this means is that we can finally understand and visualise the sequence of events in the brain that is responsible for our every move and every decision. This might even help us pinpoint where consciousness resides in our brains, and have a much deeper understanding of the same.

In recent years, MEG has gained popularity in the field of dementia research. Subtle differences among subjects, in terms of delayed responses and lower activation in specific regions of the brain measured by MEG, have helped distinguish healthy individuals from those with memory impairments and dementia. This technique is also showing potential in differentiating between various sub-types of dementia such as Alzheimer's disease, frontotemporal dementia etc.

With the help of extensive research and computational models, scientists will be able to predict when and which regions of the brain will be likely to suffer structural damage due to dementia. This will help identify people who are at risk of developing dementia in their lifetime. Not only will this allow earlier disease management, but it will also help improve the quality of life for those living with this disease.

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From RTÉ Radio 1's Today With Sean O'Rourke, can dementia be prevented?

MEG has been around since the late 1960s, but its initial sensitivity was quite low. Over the years, development of technology has allowed for efficient and highly sensitive brain mapping of patients. MEG is showing promise not only in the field of dementia, but other neurological disorders as well, such as epilepsy. Some clinicians are currently employing MEG to diagnose epilepsy, and to identify epileptic brain regions for surgical planning.

A critical advantage of MEG over currently used imaging techniques like PET, MRI or CT is that it doesn’t employ radioactive dyes, or strong magnetic fields or X-rays. It is a non-invasive, extremely safe technology, that has even been performed on expecting mothers to study cognitive development of foetuses.

MEG is a budding prospect in the world of imaging that allows us to understand brain networks in great detail. At present, there are only about 100 MEG scanners in the world, one of which is located at Ulster University's Magee campus. Currently primarily being used for research purposes all around the world, it won’t be long when it will become an integral part of diagnostic protocols given its efficiency and efficacy.


The views expressed here are those of the author and do not represent or reflect the views of RTÉ