A gene linked to the amount of grey matter in our brains – and therefore our intelligence – has been identified.
Scientists found a variant of the gene was associated with a thinner cerebral cortex – the outer layer of the brain known as grey matter – and that those who had it tended to do less well in verbal and non-verbal reasoning tests.
Previous studies have shown the cerebral cortex plays a key role in memory, attention, perceptual awareness, thought, language and consciousness.
However, the latest research, led by scientists at King’s College London’s Institute of Psychiatry, is the first to identify a genetic connection between intelligence and grey matter.
It is not known how the study, conducted among nearly 1,600 14-year-olds, applies to the wider population, but the results were confirmed by looking at the same gene, NPTN, in mice.
Dr Sylvane Desrivieres, lead author of the study in the journal Molecular Psychiatry, said the genetic variation was linked to communication between brain cells. ‘This may help us understand what happens in certain forms of intellectual impairments, where the ability of the neurons to communicate effectively is compromised.
It was revealed that teenagers carrying a particular gene variant had a thinner cortex in the left cerebral hemisphere, particularly in the frontal and temporal lobes. And they tended to perform less well in tests.
The genetic variation affects the expression of the NPTN gene, which encodes a protein that affects how brain cells communicate.
The team also looked at the NPTN gene in mouse and human brain cells.
It was 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 sensitive to the effects of NPTN mutations.
Their findings suggest that some differences in intellectual abilities can be caused by the decreased function of the NPTN gene in parts of the left brain hemisphere.
The genetic variation identified in this study only accounts for an estimated 0.5 percent of the total variation in intelligence.
Researchers hope that the study, published in Molecular Psychiatry may help experts understand some of the biological mechanisms behind mental disorders.
And it is hoped that in future the findings may help us more effectively diagnose and treat psychiatric disorders such as schizophrenia and autism.