Brain waves
Image: digitalbob8 on Flickr

An international research team from the University Medical Centre Amsterdam and Imperial College London has made a major advance in understanding the genetic foundations of intelligence. Using a large data set of more than 78,000 individuals with information on DNA genotypes and intelligence scores, the team discovered new genetic roots for intelligence.

This is the first time that scientists have identified two clusters of genes directly linked to human intelligence. Called M1 and M3, these clusters appear to influence cognitive function, which includes memory, attention, processing speed and reasoning. Crucially, these two clusters are likely to be under the control of master regulator switches.

A depiction of the double helical structure of DNA. Its four coding units (A, T, C, G) are color-coded in pink, orange, purple and yellow. Credit: NHGRI

Intelligence is one of the most examined characteristics in humans and high intelligence is associated with important economic and health-related life outcomes. Despite high heritability estimates of 45% in childhood and 80% in adulthood, only a handful of genes had previously been associated with intelligence and for most of these genes, the findings were not reliable.

In the study, the international team of researchers looked for genetic markers linked to intelligence in 13 different groups of people of European descent. They looked at samples of human brain from patients who had undergone neurosurgery for epilepsy. The researchers analyzed thousands of genes expressed in the human brain and then combined these results with genetic information from healthy people who had undergone IQ tests. Among the 52 genes they found, 40 were new ones that predominantly switched on in the brain.

To double-check their findings, the scientists applied their results to another genome-wide association study. Therefore, they studied the genetic information from people with neurological disorders such as autism spectrum disorder and intellectual disability. They discovered that some of the same genes that influence human intelligence in healthy people were also the same genes that cause reduced cognitive ability and epilepsy when mutated.

What’s exciting about this is that the genes we have found are likely to share a common regulation, which means that potentially we can manipulate a whole set of genes whose activity is linked to human intelligence – lead author of the study Dr. Michael Johnson

This study shows how we can use large genomic datasets to uncover new pathways for human brain function in both health and disease. Eventually, we can hope that this sort of analysis could provide new insights into better treatments for neurodevelopmental diseases such as epilepsy. Furthermore, research like this can help us to identify which traits can be influenced by education or genetic roots.