Aug. 8, 2014

By Medical Discovery News

What do brain scientists and fans of E. L. James have in common? They are both passionate about shades of grey. Results from a recent study in the scientific journal “Molecular Psychiatry” indicate that grey matter really does, well, matter. This study shows that the thickness of grey matter in the brain may be linked to intelligence and may also explain why some people have learning difficulties.

Grey matter is the outermost region of the brain, a layer of tissue two to four millimeters thick covering the brain on both sides with a wrinkled surface. Underneath the grey matter, also called the cerebral cortex, is the white matter of the brain, the cerebrum.

Grey matter is responsible for some major human functions including awareness, attention, consciousness, language, thought, and memory. Previous studies have shown that animals with bigger brains generally have thicker cortexes, but there has not been a strict link between intelligence and the thickness of the grey matter until now. 

For this new study, researchers at King’s College London’s Institute of Psychiatry obtained brain scans and DNA samples from 1,583 14-year-olds. They also tested the verbal and nonverbal intelligence of these subjects. Using DNA analysis, scientists looked for gene variants that could be responsible for the intelligence differences of this group. This proved to be a daunting task as they discovered more than 50,000 gene variants associated with brain development. However, with the help of computation biology, researchers uncovered some astounding results. Those with one particular gene variant caused by a single nucleotide polymorphism (or change) had thinner grey matter on the left side of their brains. And, these same individuals tested lower on the intelligence tests. 

Called NPTN, this gene encodes a protein that works in brain cells called neurons. The variant of NPTN affects communication between neurons in the brain, thereby explaining its impact on important functions of grey matter. Additional experiments suggest the NPTN variant may have more of an effect in the left side of the brain than the right side. This may correlate to lower intelligence due to the function of this important gene and its encoded protein in the left brain. 

While important, NPTN is not the only thing that determines intelligence – a multitude of other genes and environmental influences are clearly involved as well. However, this gene may provide new clues as to how intelligence is built in humans. Also, it will be interesting to see if this gene variant is associated with cognitive diseases like autism or psychological disorders like schizophrenia. 

Thanks to the new B.R.A.I.N. initiative that funds basic and translational research, we look forward to better understanding the human brain, arguably one of the most important human organs we know the least about. 

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