Authors from more than 200 institutions have combined their efforts to publish a massive and comprehensive study of genetic effects on brain growth.

Though previous research has shown that genetics have a non-negligible impact on brain development, this paper — published in the journal Nature — combined data taken from 30,717 participants’ genomes and size measurements of brain structures to identify six genes that previously had no known effect on brain growth. The parts of the brain considered by the study play integral roles in learning, memory and motivation.

“This work shows mainly that there are clear and robust genetic effects influencing the variation of brain volume,” said Alejandro Arias-Vásquez, the paper’s co-lead author and a researcher in the Department of Human Genetics at Radboud University in the Netherlands.

The study, to which more than 300 scientists — including several Yale researchers — contributed, including analyzed data from participants’ genes and MRI scans. Participants ranged in age from nine to 97 years old. Two gene loci — places in one’s genetic code where a gene may vary from person to person — were found to have effects on the volume of the hippocampus, a part of the brain often associated with memory formation. Three loci were found to have effects on the volume of the putamen, a structure in the brain that plays an integral role in motor function. Another locus was responsible for size of the ICV, another brain structure near the hippocampus and putamen.

According to Miguel Renteria, co-lead author of the paper and a researcher at the QIMR Berghofer Medical Research Institute in Australia, the study’s massive sample size was necessary in order to detect the subtle effects of gene variation on brain structure. The collaboration between hundreds of scientists was necessary because medical data sharing among separate research teams raises ethical questions, Renteria added.

“This is the only way,” said Arias-Vásquez of the collaborative nature of the study. “Regardless of your study design or the hypothesis you want to test, I’m convinced that pulling together resources and putting heads together is more beneficial than problematic. It requires leaving your ego at the door and putting aside petty differences of opinion.”

According to Derrek Hibar, researcher at the Keck School of Medicine at the University of Southern California and co-lead author of the paper, the study would have taken at least 10,000 participants for even the strongest results of the study to be statistically significant. However, the researchers were still surprised at the strength of certain correlations, particularly between the rs945270 gene and putamen size.

Arias-Vásquez, Renteria and Avram Holmes, a co-author of the study and a Yale psychology professor, said they see the field of genetic neuroscience moving toward using larger groups of researchers as greater sample sizes are needed for significant results.

“In neuroscience and neurogenetics in particular, we are rapidly going to the point where we are realizing we are tackling the same problems, and so consortia are starting to form up where investigators are pooling resources to try to hit some of these pressing problems,” Holmes said.

This is the second paper published by the group, the ENIGMA Consortium, which is dedicated to bringing together researchers from various fields to better understand how the brain works.