The brain is a very complex organ, and its structure is largely shaped by genetics. To understand more about how changes in the brain’s structure can lead to disease or alterations in behaviour, researchers analysed data from genome-wide association studies (GWAS) in the largest collaborative study of the brain to date to find out how common genetic variants affect the structure of these brain regions.
In a project including around 300 scientists and 190 institutions from across the world, including from the Alzheimer’s Disease Neuroimaging Initiative, the CHARGE consortium, the EPIGEN consortium, the IMAGEN consortium and the SYS group, researchers analysed brain GWAS data. These researchers, part of the Enhancing Neuro Imaging Genetics through Meta Analysis (ENIGMA) Network, focused on genetic influences on the volumes of seven subcortical regions and the intracranial volume and linked in with magnetic resonance images of 30,717 individuals from 50 cohorts in 33 countries. These regions of the brain coordinate movement, learning, memory and motivation.
“ENIGMA’s scientists screen brain scans and genomes worldwide for factors that help or harm the brain — this crowd-sourcing and sheer wealth of data gives us the power to crack the brain’s genetic code,” says Paul Thompson of the University of Southern California.
The analysis found five novel genetic variants that had an influence on the volume of the putamen and caudate nucleus, as well as supporting evidence for three known loci previously linked with hippocampal volume and intracranial volume. Several of these are found in over one-fifth of the world’s population. People who carry one of those eight mutations had, on average, smaller brain regions than brains without a mutation but of comparable age, and some of the genes are implicated in cancer and mental illness.
“Our global team discovered eight genes that may erode or boost brain tissue in people worldwide. Any change in those genes appears to alter your mental bank account or brain reserve by 2 or 3 percent,” says Thompson.
These findings could at least partly explain the variability in human brain development seen between different people. It may also help researchers to understand more about neuropsychiatric diseases including Alzheimer’s disease, autism and depression, and identify the people who would most benefit from new drugs designed to save brain function. However, more research is necessary to determine if the genetic mutations are implicated in disease.