Several genes which contribute to brain size have been identified by a consortium called Enigma. Over 30,000 brain scans were compared with people’s DNA, which has located genes which affect the size of structures in the brain as well as its overall volume.
Paul Thompson, a neuroscientist who is the head of the Imaging Genetics Centre at the University of Southern California, is involved in the research. He says “What Enigma is doing is combing through every pixel of every scan and comparing it to every genome. This is a roadmap to how you do this.” The paper was published in Nature, and details that 30,717 brain scans with DNA information was used. Thompson claims that it is the biggest collaboration ever to combine efforts to study the brain, with the paper having 287 authors and 193 institutions listed.
MRI scans cost around £600 each, so it is expensive to gain the required amount of data. The research has mainly been funded by a $32 million grant awarded to Enigma and several other centres. This is part of the half a billion dollar investment in exploiting biological data being distributed over the next seven years by the Nation Institutes for Health. As well as new scans, they utilised $30 million worth of brain scans taken from people between the ages of nine to 96 years old previously for other studies.
The putamen, a part of the brain that influences movement and learning, was on average 2.8% smaller in people with variants of two genes. Thompson says that this is interesting, as this region is smaller in people suffering from Parkinson’s and Huntington’s disease.
Despite all of the data, there was nothing showing links to psychiatric illnesses. Thompson says that there are clues pointing in this direction however. “It might not be as simple as the gene gives you a smaller putamen and you get these diseases, but the genes are likely to affect how many cells you have, and how they get to the right place,” he says. “It’s vital to know how it’s built.”
Thompson is convinced that with advances in the field and mathematics, there will be patterns identified within the data. Critics point out that the research completely down plays the role of environmental influences and life events, such as exercise and stress. However, Thompson hopes that the research will lead to substantial breakthroughs in brain science in time.