Iron plays a vital role in the development of the brain -- too little can result in cognitive problems, too much promotes degenerative diseases such as Alzheimer's and Parkinson's.

Iron deficiency is the most common nutritional deficiency worldwide, causing poor cognitive achievement in school-aged children. Now it has been found to affect the brain's physical structure as well.

Paul Thompson, professor of neurology at the University of California Los Angeles, and colleagues measured levels of transferrin, a protein that transports iron throughout the body and brain, in adolescents.

Since both a deficiency and an excess of iron can negatively impact brain function, the body's regulation of iron transport to the brain is crucial, the journal Proceedings of the National Academy of Sciences reports.


When iron levels are low, the liver produces more transferrin for increased iron transport. The researchers wanted to know whether brain structure in healthy adults was also dependent on transferrin levels, according to a California statement.

"We found that healthy brain wiring in adults depended on having good iron levels in your teenage years," said Thompson, member of California's Lab of Neuro Imaging.

"This connection was a lot stronger than we expected, especially as we were looking at people who were young and healthy - none of them would be considered iron-deficient.
"We also found a connection with a gene that explains why this is so. The gene itself seems to affect brain wiring, which was a big surprise," he said.
Thompson's findings are based on MRI scans on 615 healthy young-adult twins and siblings, who had an average age of 23.

By averaging the subjects' transferrin levels, which had been assessed repeatedly - at 12, 14 and 16 years of age - the researchers estimated iron availability to the brain during adolescence, Thompson  said.