You might have heard of iron deficiency anemia. Iron is the central element in hemoglobin, the oxygen-carrying protein of our blood. Having low concentrations of iron can lead to not having a proper circulation of oxygen, which usually translates to feeling tired or weak. However, there is also iron stored in tissues, including the brain. There, it helps with the cell’s production of energy, with the formation of myelin (i.e. white matter), and it is used by different enzymes that produce neurotransmitters.

Much like everything brain-related, the concentration of tissue iron in the central nervous system needs to stay in a perfect balance. Too much iron might lead to an increased chance of neurodegeneration, too little iron might cause irreversible changes in brain chemistry. But what was previously unknown was whether teenagers were particularly susceptible to iron deficiency, as much as babies and children can be. A group of scientists from the University of Pennsylvania has now shown that there is a correlation between brain tissue iron during adolescence with cognitive abilities.

Bart Larsen and their colleagues analyzed brain scans of 922 humans (8-26 years old). Using a technique called R2* relaxometry, they were able to quantify the concentration of iron in the brain by magnetic resonance. This concentration, especially in a brain region called basal ganglia increased over time in all samples. However, there were some observed sex differences, with women's brains reaching a peak of iron concentration earlier. By doing a battery of neurocognitive tests, the researchers found that there was a correlation between how much iron was being accumulated over time with a person's cognitive performance.

Although only a correlation, studies like this are important in finding how different external factors affect our development. Worth pointing out: iron deficiency is still a problem in the US affecting 15% of women and 3% of men. With this new study, we are more aware of the importance of iron in the normal brain development of teenagers.