Scientists have identified a fluid drainage system in the brain that sheds light on the underlying mechanisms of brain ageing and age-related Alzheimer's disease.

The study demonstrated that meningeal lymphatic vessels in the brain play an essential role in maintaining a healthy homeostasis in ageing brains and could be a new target for the treatment. These vessels drain fluid from the central nervous system into the cervical lymph nodes and dysfunction of that drainage aggravates cognitive decline as well as Alzheimer's disease pathology.

Moreover, when the healthy aged mice were treated with a molecule that increased meningeal lymphatic vessel size and fluid flow within those vessels, the mice showed improved performance on learning and memory tasks. "As you age, the fluid movement in your brain slows, sometimes to a pace that's half of what it was when you were younger," said Jennifer Munson, Assistant Professor at the Virginia Polytechnic Institute and State University (Virginia Tech), in the US.

"We discovered that the proteins responsible for Alzheimer's actually do get drained through these lymphatic vessels in the brain along with other cellular debris, so any decrease in flow is going to affect that protein build-up," she added. For the study, published in the journal Nature, the team engineered a hydrogel that can swell those lymphatic vessels.

As a result of the treatment, the bulk flow of fluid in the brain actually increased, and that seemed to have a positive effect on cognitive abilities. Munson noted that older mice with normal, age-impaired cognitive abilities experienced the biggest gains in memory and learning from the treatment. "Our results showed that someday this method could be used as a potential treatment to help alleviate the effects not only of Alzheimer's, but also other age-related cognitive ailments," Munson said.