Your brain is similar to your room. If you have a cluttered room, it can become a breeding ground for disease, chaos and inefficiency. Similarly, a ‘dirty brain’ can cause trouble. Our brain has an ingenious system to clear out dirt and harmful waste. However, if that system becomes impaired for some reason, it may lead to dirty-brain diseases―such as Alzheimer’s and Parkinson’s. These diseases are characterised by the brain’s inability to effectively clear harmful waste products, primarily due to the decline of the glymphatic system, a waste removal mechanism.
Ageing is an important factor in the development of dirty-brain diseases, as it can affect the waste-clearing process. Now, a new study suggests that it may be possible in the future to reverse this age-related impairment and restore the brain’s waste-clearing mechanism.
The study was done by researchers at the Hajim School of Engineering and Applied Sciences at Rochester, New York, and the University of Rochester’s Medical Center. The researchers focused on the glymphatic system, which utilises cerebrospinal fluid to flush out excess proteins generated by neurons and other brain cells during normal activity. As individuals age, the efficiency of this system diminishes, leading to the accumulation of toxic proteins associated with various neurological disorders.
Once laden with protein waste, cerebrospinal fluid in the skull must travel to the lymphatic system and eventually reach the kidneys for processing. Advanced imaging and particle-tracking techniques have revealed the route by way of the cervical lymph vessels in the neck through which half the dirty cerebrospinal fluid exits the brain. Unlike the cardiovascular system, which has the heart as its sole pump, fluid in the lymphatic system is transported by a network of tiny pumps. These microscopic pumps, called lymphangions, have valves to prevent backflow and are strung together to form lymph vessels.
The researchers observed that in older mice, the frequency of contractions of this system decreased and valves failed, slowing the flow of dirty cerebrospinal fluid out of the brain by 63 per cent compared to younger mice.
The researchers applied prostaglandin F2α, a drug already being used clinically, to the cervical lymph vessels in older mice. It was then observed that the frequency of contractions and the flow of dirty cerebrospinal fluid from the brain both increased, returning to a level of efficiency found in younger mice. Prostaglandin F2α is a hormone-like compound commonly used medically to induce labour and known to aid smooth muscle contraction. This breakthrough offers a potential new treatment strategy for neurodegenerative diseases.