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Some people lose their sharpness of mind as they age, while others retain their wit and acuity. Researchers do not know why, but Naiara Demnitz, Ph.D. in Psychiatry and researcher at Hvidovre Hospital, has a hypothesis: the difference may lie in how efficiently cerebrospinal fluid moves through the brain as we age. Whether this is true is what she will now investigate in a large study with support from the Lundbeck Foundation. 

"This is a fantastic opportunity for me to conduct large-scale research that will broaden our understanding of how a healthy brain can be maintained even in old age," she says. 

Using a new method, she will examine how efficiently cerebrospinal fluid flows in 450 healthy older adults, and whether this is linked to cognitive function. At the same time, in a randomised trial involving 90 older adults, she will investigate whether three months of aerobic exercise can improve cerebrospinal fluid flow and help older adults maintain their cognitive capacity. 

"We know that exercise matters for how the brain ages, but we do not know why. I want to find a mechanistic explanation — because then we can more purposefully work with exercise that influences the brain." 

The new method Naiara Demnitz will use was developed by researchers at Leiden University in the Netherlands. They have shown how a so-called 7T MRI scanner — whose magnetic field is many times stronger than a conventional MRI scanner — can be used to zoom in on very small areas of the brain and measure how cerebrospinal fluid moves. 

The only scanner of this type in Denmark is located at the Danish Research Centre for Magnetic Resonance (DRCMR) at Hvidovre Hospital, where Naiara Demnitz works. 

"With this method, we can whether cerebrospinal fluid flow is associated with brain function and structure in old age,” says Naiara Demnitz. 

Accumulation of waste products in the form of protein fragments in the brain is found in people whose memory deteriorates with age, and is also a marker for, among other conditions, Alzheimer's disease. 

The group of 450 older adults that Naiara Demnitz will invite to participate in the study was established by researchers at Bispebjerg Hospital ten years ago. It is called LISA. 

"The group is completely unique, and it is the reason I came to Copenhagen to do research. The older adults have been regularly and thoroughly examined — including with brain scans — so we have a large dataset about them, their health and their lifestyle," explains Naiara Demnitz. 

Some of the older adults meet the definition of superagers — showing very few signs of cognitive decline with age. And they are the group Naiara Demnitz is particularly interested in, because their lifestyle and behaviour may influence the efficiency of the brain's cleansing system. And it may be the study of their brains that reveals how to retain a sharp mind. 

"I have worked on ageing since my PhD and have always been fascinated by the plasticity of the brain. It is remarkable that through our lifestyle and behaviour, we can influence the brain's chemistry and structure," she says. 

"We usually talk about disease and decline when we talk about ageing, but I would rather focus on the fact that we can do something to preserve cognitive capacity."