An international team of scientists has successfully mapped the human genes that either increase or disrupt the brain's resistance to various neurological and mental illnesses. This study, presented in the journal Nature Genetics, has identified novel genes that could provide insight into the differences that exist in brain size and intelligence. The results could also lead to the development of new drug treatments.
'Our individual centres couldn't review enough brain scans to obtain definitive results,' says Professor Thompson. 'By sharing our data with project ENIGMA, we created a sample large enough to reveal clear patterns in genetic variation and show how these changes physically alter the brain.'
What set this work apart from past research studies was that researchers measured the brain's size and memory centres in many magnetic resonance imaging (MRI) images from more than 21 100 healthy subjects, while screening their deoxyribonucleic acid (DNA) as well.
'Millions of people carry variations in their DNA that help boost or lower their brains' susceptibility to a vast range of diseases,' the UCLA researcher says. 'Once we identify the gene, we can target it with a drug to reduce the risk of disease. People also can take preventive steps through exercise, diet and mental stimulation to erase the effects of a bad gene.'
The team also found genes that explain individual differences in intelligence, uncovering a variant in a gene called HMGA2 that affected both brain size and intelligence. DNA has four bases: A, C, T and G; subjects whose HMGA2 gene had C instead of T had larger brains and recorded higher results on standardised intelligence quotient (IQ) tests.