Ageing often makes itself visible in familiar ways, from grey hair and wrinkles to lapses in memory. That has fuelled a longstanding scientific question: could some of those changes eventually be slowed, prevented, or even reversed?
Research involving a group of scientists from Xi’an Jiaotong-Liverpool University, Stanford University, Shanghai Jiao Tong University, and the University of Chinese Academy of Sciences points to an intriguing possibility. In experiments with aged mice, researchers found that dietary supplements containing compounds associated with Ascidiacea, commonly known as sea squirts, reversed several signs linked to ageing.
An Unusual Source of Anti-Ageing Compounds
Sea squirts are marine animals that people eat in parts of Asia, including Korea (where they are known as meongge, or 멍게) and Japan (hoya, or ホヤ). They can be eaten raw and contain high levels of compounds called plasmalogens.
Plasmalogens are a type of lipid, or fat molecule, that forms an important part of cell membranes. They occur naturally throughout the human body and are especially abundant in the brain, heart, and immune cells. Their levels tend to decline as people grow older.
Reduced plasmalogen levels have also been observed in several neurodegenerative diseases, including Alzheimer’s disease and Parkinson’s disease. That connection has led researchers to investigate whether restoring plasmalogens could help protect the brain from some of the changes associated with ageing.
To explore that possibility, the team added plasmalogens to the diets of aged mice and examined how the supplements affected both their behaviour and their bodies.
The results were striking. The treated mice showed substantial improvements in learning and displayed visible physical changes as well.
Professor Lei Fu, the corresponding author of the study, says, “Our research suggests that plasmalogens may not just stop cognitive decline but may reverse cognitive impairments in the ageing brain. Additionally, aged mice fed with the plasmalogens grow new black hair that is thicker and glossier than aged mice not fed the supplement.”
According to the researchers, the work provides the first detailed look at how plasmalogens may influence the ageing brain.
Ageing Mice Show Improved Memory
To measure learning and memory, the scientists used a common laboratory experiment called the Morris water maze. In this test, mice are placed in a pool containing a hidden platform where they can rest.
Because mice generally prefer to escape the water, they gradually learn where the platform is located. After several days of training, younger mice typically remember its position and swim toward it quickly. Older mice often need more time to locate the platform, reflecting the decline in learning and memory that can accompany ageing.
After five days of training, aged mice receiving plasmalogens performed much more like younger animals. They reached the platform significantly faster than aged mice that had not received the supplement.
The researchers then examined the animals’ brains to determine what might explain the improvement.
They found that mice given plasmalogens had more synapses, and these synapses appeared to be in better condition than those in untreated aged mice.
Synapses are the tiny junctions through which nerve cells communicate. They allow signals to pass through neural networks and are essential for learning, memory, and many other brain functions.
Restoring Connections in the Ageing Brain
Synapses are highly adaptable early in life. This ability to change and form new connections, often called neural plasticity, helps the brain learn new information and skills.
With age, however, synapses can become less numerous and less effective. Similar deterioration is also associated with neurodegenerative diseases and can contribute to declining cognitive abilities.
In the experiment, aged mice receiving plasmalogen supplements appeared better able to form new neural connections and learn new tasks than mice eating a normal diet. The findings suggest that increasing dietary plasmalogens may help protect synapses from some forms of age-related deterioration.
The researchers also identified another important difference between the groups: inflammation in the brain was substantially lower among mice receiving plasmalogens.
Inflammation is part of the body’s normal immune response, but chronic or excessive inflammation in the brain can become harmful. As the brain ages, immune activity can become dysregulated, potentially damaging nerve cells and disrupting communication between synapses. Persistent inflammation is also considered an important contributor to several neurodegenerative disorders.
The reduction in inflammation seen in the plasmalogen-treated mice could therefore help explain why they performed better on tests of learning and memory.
How Plasmalogens Might Work
Scientists do not yet know exactly how dietary plasmalogens produce these effects. Professor Fu outlined several possible mechanisms.
“We found that plasmalogens significantly increase the number of molecules that aid the growth and development of neurones and synapses in the brain. This suggests that plasmalogens can promote neuroregeneration.
“There is also an increasing body of evidence that plasmalogens directly affect the structural properties of synapses. Plasmalogens may increase the fluidity and flexibility of synaptic membranes, affecting the transmission of impulses between neurones.”
Neuroregeneration refers to the repair, renewal, or regrowth of nerve cells and their connections. If plasmalogens support that process, they could potentially help the ageing brain maintain or rebuild some of the neural circuitry needed for memory and learning.
The researchers also believe that the effects may extend beyond what happens directly inside the brain.
Professor Fu points to the gut-brain connection as another possible pathway.
“Some studies have shown that dietary plasmalogens affect the microorganisms in the gut. It has been widely reported that the connection between the organisms in our gut and our brain influences neurodegeneration. It may be the plasmalogen’s effect on this connection that causes the improvements in learning and memory seen in this study.”
The gut contains enormous communities of bacteria and other microorganisms, collectively known as the gut microbiome. Research increasingly suggests that these microbes can influence the brain through immune signals, metabolism, and other biological pathways. Scientists often refer to this two-way communication system as the gut-brain axis.
Could Plasmalogens Eventually Help People?
Professor Fu has such confidence in the findings that he personally takes a plasmalogen supplement every day.
“For the first time, we show that plasmalogen supplements might be a potential intervention strategy for halting neurodegeneration and promoting neuroregeneration.
“The oral intake of plasmalogens could be a feasible therapeutic strategy to improve cognitive function in older people.”
The findings are intriguing, but they come from an animal model. Improvements observed in mice do not necessarily mean that eating sea squirts or taking plasmalogen supplements will reverse ageing in humans. Additional research would be needed to determine whether similar effects occur in people, what doses might be effective, and whether long-term supplementation is safe.
Still, the results raise an unusual possibility. A compound found in an edible marine animal may offer scientists a new way to investigate how ageing affects the brain and whether some of those changes can eventually be reversed.
