Neurology researcher wins prestigious prize for discovery of brain’s cleaning system
Maiken Nedergaard is awarded the Nordic Fernström Prize “for her revolutionary discovery of the brain’s own cleaning system, the glymphatic system. Her discovery and investigation of this system has increased our understanding of how the brain gets rid of harmful products during sleep, thereby protecting the brain from disease”.
Maiken Nedergaard’s research has increased our knowledge of how the brain gets rid of spent proteins, i.e. harmful waste products, while we are asleep. The process protects the brain from diseases and is known as the glymphatic system. Maiken Nedergaard compares it to a washing-machine.
“All biological activity generates waste; that is a fundamental principle. You could compare it to an aquarium: if you don’t keep it clean, sooner or later the fish die”, says Maiken Nedergaard, professor of neurology, who is currently working at the University of Copenhagen and the University of Rochester.
This also applies to the body’s organs, in which old, damaged or hazardous cells or part of the cells are transported away through the finely meshed lymphatic system, which drains into the bloodstream. The brain, which would need to get rid of around 7 grams of harmful proteins every day, has no such lymph system. It was therefore thought that the brain took care of its own waste products and recycled them. However, Maiken Nedergaard, who started researching the brain during her medical degree programme, did not think this theory made sense.
“It did not seem like a good design that all the harmful waste products produced daily would have to be recycled by the brain cells themselves, which other organs could just dump their waste into the lymph vessels. We know that several of these proteins, including amyloid and tau are involved in neurodegenerative diseases. So we asked whether the brain contained something that worked as lymph vessels, but was built differently. It can be compared to breaking a house built by Lego blocks down and then rebuilding a new house using a different construction.”
The blood vessels in the brain are surrounded by something called the perivascular space. It looks like a doughnut-shaped tunnel and is created by surrounding glial cells that form the outer wall. Maiken Nedergaard’s research showed that cerebrospinal fluid passed through this space, rinsing away the waste proteins no longer needed by the brain. She has also shown that, as we sleep, the space expands and more fluid flows through the tunnel and down towards the veins, finally reaching the neck where it joins the bloodstream.
“Just as the heart pumps blood around the body, it also pumps cerebrospinal fluid through the perivascular space, which is formed by the glial cells in the brain. The beauty of the glymphatic system is that it removes all harmful proteins and other waste, not only one kind”.
The discovery is important because a common characteristic of many neurodegenerative diseases such as Alzheimer’s, Huntington’s and Parkinson’s, is the accumulation of harmful proteins in the brain. These diseases also have in common the early onset of sleep disorders in patients.
“We have seen that how our heart beats have a major effect on the glymphatic system. When we sleep, our heart rate slows down and the heart’s output increases, which means the system functions optimally. But as we age, our blood vessels become stiffer. Even though the heart manages to pump blood around the body, it is not sufficient to pump the fluid in the brain as well as before. The cleaning programme is then not as efficient”, observes Maiken Nedergaard.
When she published the news, it did not initially provoke very strong reactions. Only once it was clear that the system is only in use while we sleep did it create a sensation.
How did it feel when you realised your theory was correct?
“As a researcher, when you find something surprising, you immediately assume it must be a mistake. But then you continue and repeat the experiments in various ways, and in the end you know it is correct. The satisfying moment is not when you publish or talk about the finding. It is when you finally believe in it yourself. The world itself is so confused, so understanding just a bit more of the puzzle is what drives science. The insight may also allow you to look at something you already know in a new perspective.
The call to tell her that she had been awarded the Nordic Prize was unexpected.
“I am incredibly grateful for the award! It came as a big surprise; my first reaction was that there must have been a mistake. These kinds of research prizes are important; they generate attention for all the fantastic progress being made within research. As President of the Danish Society for Neuroscience which, among other things, mediates contacts and collaborations in the field between the Nordic countries, this Swedish prize is especially significant to me”, says Maiken Nedergaard.
Maiken Nedergaard, Professor in Neurology, Copenhagen University, Denmark and University of Rochester, USA
nedergaard [at] sund [dot] ku [dot] dk
Eric K. Fernström’s six local prizes and the Nordic prize will be awarded during the popular science event Research Day on 7 November in Lund. Journalists who wish to meet the prize-winners will have an opportunity to do so on the day.
Every year, the Eric K. Fernström Foundation awards a Nordic Prize to a medical researcher from one of the Nordic countries, as well as local prizes to junior researchers at faculties of medicine in Sweden. The Nordic Prize has a value of one million Swedish crowns. The prizes are awarded as a festive grand finale of Research Day in Lund, this year on 7 November. Lund University’s Faculty of Medicine has collaborated with the foundation since 1978, when Honorary Doctor of Medicine Eric K Fernström started the Eric K. Fernström Foundation through a donation.