First, the researchers showed that spermidine could pass through the brain barrier. It is a significant discovery given that few compounds, be they natural or manufactured, can pass through this brain barrier. This means that spermidine cans have a direct positive effect on our brain cells. Second, spermidine increases mitochondria function. Mitochondria are cell organelles that produce energy (ATP) through cellular respiration. In addition, mitochondria have been closely linked to many processes determining our lifespan. In this study, the researchers showed that spermidine increased the brain's cellular respiration, which means more energy for our brain cells. Interestingly, the researchers noted that spermidine could only have these positive effects on our neurons if autophagy were upregulated.
In other words, they found that if they were to block autophagy, all of the benefits would also be blocked, which adds more support that spermidine functions through autophagy. Finally, and more practically, the researchers also showed that spermidine improved cognitive learning, such as spatial learning (our brain senses the environment). Those who forget where we left our car keys or parked our car may benefit from some spermidine improved spatial learning!