The natural substance spermidine is contained in wheat germ, nuts, mushrooms and many other foods and has been researched for a long time because of its health-promoting effects. Now studies suggest that the spermidine could also help against the mental decline in old age. Older mice and humans performed significantly better in learning and memory tests if they had consumed food with a higher spermidine content. According to more detailed analyzes, the spermidine strengthens the function of the mitochondria in the brain – the cells’ energy suppliers.
Even in people who do not suffer from Alzheimer’s disease or any other pathological dementia, intellectual performance decreases with age. In particular, memory and the ability to learn deteriorate over the years. The cellular and molecular mechanisms underlying this mental degradation, however, have so far hardly been clarified. This makes it difficult to develop effective preventive and therapeutic treatments. However, there are suspicions that the decline in brain performance is related to a function of the mitochondria that deteriorates with age – the organelles that provide chemical energy for cellular processes. Due to the high energy consumption of the nerve cells, mitochondria are of particular importance in the brain. At the same time, autophagy probably also plays a role – the process by which cells dispose of damaged cell parts and waste materials, thus enabling regeneration.
The memory of old mice is strengthened
One substance that seems to play an important role in both processes is spermidine. This substance is produced by all living cells and is also found in abundance in many foods, especially whole grains, wheat germ, mushrooms, some cheeses and meats. A few years ago, animal experiments suggested that a diet rich in spermidine can prolong the life of roundworms and flies and also show cognitive effects in higher animals. Sabrina Schroeder from the University of Graz and her colleagues have now examined in more detail how pronounced this effect is on the memory and intellectual performance of mice and humans. In the first experiment, they enriched the feed of older mice with spermidine for six months. At the beginning and during this time, they examined the learning behavior and memory of the treated mice and of control animals in several standardized tests, including a test in which the mice had to remember the position of platforms under the water surface.
“It has been shown that orally administered spermidine reaches the brains of mice and that these perform better in various memory tests with age than mice that were not given an extra portion of spermidine,” reports Schroeder’s colleague Andreas Zimmermann. More detailed analyzes showed that the spermidine-fed mice had a significantly increased mitochondrial function in the hippocampus compared to the control animals of the same age – an area of the brain that is important for learning and memory. The spermidine thus promotes a biochemical reaction chain through which the production of certain proteins of the mitochondria is stimulated, at the same time the autophagy is promoted. “These data support the assumption that spermidine, which stimulates autophagy, can also improve the cognitive performance of aging animals,” states the research team.
Also has a positive effect on humans
This raised the question of whether these positive effects can also be seen in humans. To find out, Schroeder and her team evaluated the data of 800 older participants in a long-term study from South Tyrol. They received intensive medical and psychological support from 1995 to 2000 and regularly examined their cognitive performance using a battery of standardized tests. In addition, it was recorded how much spermidine the test persons ingested with their food or with food supplements. The result: Participants who had consumed more spermidine during the study period showed significantly fewer cognitive losses over the next five years than people of the same age and from comparable circumstances whose diet had contained less spermidine. “This relationship was noticeable in women and men and remained consistent within different age groups and categories,” the scientists write. The positive effect of spermidine on mental performance also became clearer with the dose ingested.
According to the research team, this suggests that a diet rich in spermidine can also improve cognitive performance in old age. “The combination of epidemiological and experimental data opens up the exciting possibility that spermidine could protect people against mental degradation,” say Schroeder and her colleagues. This could create new opportunities for therapy and prevention. “The observations show a connection that should be confirmed in the near future with an intervention study, especially since there are very few possibilities of a positive influence in the cognitive area”, says co-author Stefan Kiechl from the Medical University of Innsbruck.
Source: Sabrina Schroeder (University of Graz) et al., Cell Reports, doi: 10.1016 / j.celrep.2021.108985555