Genetic Variation Linked To Intellectual Ability
February 12, 2014

Scientists Identify Gene Linking Thickness Of Grey Matter In The Brain To Intelligence

Brett Smith for - Your Universe Online

Previous research studies have demonstrated that the thickness of the cerebral cortex, or “cortical thickness,” is closely related to intellectual ability, and a new study from scientists at King's College London has revealed a gene related to both cortical thickness and intelligence .

Published in the journal Molecular Psychiatry, the new study could help reveal the biological mechanisms behind some forms of intellectual impairment.

"We wanted to find out how structural differences in the brain relate to differences in intellectual ability,” said study author Sylvane Desrivières, a psychiatrist from King's College London. “The genetic variation we identified is linked to synaptic plasticity – how neurons communicate. This may help us understand what happens at a neuronal level in certain forms of intellectual impairments, where the ability of the neurons to communicate effectively is somehow compromised."

"It's important to point out that intelligence is influenced by many genetic and environmental factors,” she added. “The gene we identified only explains a tiny proportion of the differences in intellectual ability, so it's by no means a 'gene for intelligence.’”

In the study, scientists analyzed DNA samples and MRI scans from nearly 1,600 healthy 14-year-old teenagers, part of the IMAGEN project – a European Commission-funded endeavor to identify and learn about biological and environmental factors that could influence brain function and mental health in teenagers. The study team looked at over 54,000 genetic variants that were potentially involved in brain development. The teenage participants also underwent a series of tests to score their verbal and non-verbal intelligence.

The study team discovered that, on average, teenagers with a particular gene variant had a thinner cerebral cortex in the brain’s left hemisphere, particularly in the frontal and temporal lobes. Teens with this variant also performed poorer on tests for intellectual ability compared to teens without the variant.

The genetic variation in question affects the expression of the NPTN gene, which encodes a protein acting at neuronal synapses, thus affecting how brain cells communicate.

To confirm that they had their gene, the study team studied the NPTN gene in mouse and human brain cells. The scientists discovered that the NPTN gene had a different activity in the left and right hemispheres of the brain, which may cause the left hemisphere to be more susceptible to the effects of NPTN mutations. Their findings suggest that some contrasts in intellectual abilities can result from the lowered function of the NPTN gene in certain regions of the left brain hemisphere.

The researchers noted that the genetic variation found in the study only accounts for about 0.5 percent of the total variation in intelligence. However, the findings may have significant implications for the study of several psychiatric disorders, such as schizophrenia and autism, where lower cognitive ability is a symptom of the disorder.

Another recent brain study, published in the journal Frontiers in Neuroinformatics, found that the brains of people with autism can create 42 percent more information on average while at rest. The researchers said this hyperactivity could explain an autistic child’s detachment from his/her environment.