Worldwide Study Unlocks Genetic Secrets of the Gray Matter

Summary: Researchers have created the first genetic map of the cerebral cortex, which identifies over 300 genetic variants that influence the structure of the brain region.

Source: University of New South Wales

A major international collaboration using data from two UNSW Centre for Healthy Brain Ageing (CHeBA)(link is external) studies, the Sydney Memory & Ageing Study(link is external) and the Older Australian Twins Study(link is external), has produced the first genetic map of the cerebral cortex, identifying more than 300 genetic variants that influence the structure of the key brain region.

The cerebral cortex, often referred to as the ‘grey matter’, plays a crucial role in thinking, information processing, memory and attention. It is the relatively thin, folded, outer layer of the brain. Its folds area way of packing in more neurons, or brain cells.

The extent of the folds – which are measured by surface area –and the thickness of the cortex have previously been linked to cognitive abilities and various psychiatric traits, including schizophrenia, bipolar disorder, depression, attention deficit hyperactivity disorder (ADHD), and autism. However, until now, not a lot was known about the genetic variants that influence the size of the surface area and thickness of the cortex.

More than 360 scientists from 184 different institutions – including CHeBA’s Co-Directors Professor Perminder Sachdev and Professor Henry Brodaty and Leader of CHeBA’s Genetics & Epigenomics Group Dr Karen Mather – contributed to the global effort, which has been published today in the prestigious journal Science.

“The longitudinal studies being conducted at CHeBA have generated rich datasets that have led to many novel discoveries, often in collaboration with several researchers overseas. This paper is another example of the rich dividends that the work of over the last 15 years is yielding,” said Professor Perminder Sachdev.

The key analysis was conducted by Dr Katrina Grasby from the Psychiatric Genetics Research Group at QIMR Berghofer, as well as other researchers from the Institute, the University of Southern California and the University of North Carolina. Dr Grasby said the researchers identified 306 genetic variants that influenced the structure of the cerebral cortex.

“We conducted this study to identify genetic variants that influence brain structure in order to shed light on how our genetics contribute to these differences among us,” Dr Grasby said.

“We found that the genetic variants that are linked to a smaller surface area of the cerebral cortex – or less folding – also contribute to a greater risk of ADHD, depression and insomnia.”

“This gives us a starting point to further explore this genetic link between the structure of the brain and ADHD.”

“Our findings are now a resource that can be used by other scientists to help answer more questions about the genetic influences on the brain and how they relate to numerous behavioural or disease outcomes.”

QIMR Berghofer’s Associate Professor Lucia Colodro-Conde, who was also a co-author, said the researchers studied MRI scans and DNA from more than 50 thousand people.

This shows the brain

Researchers identified 306 genetic variants that influenced the structure of the cerebral cortex. The image is credited to Tyler Ard, James Stanis, and Arthur Toga.

“By analysing brain images and genetic information from such a large group of people, we were able to predict one third of the differences in cortex structure between individuals with genetic variants,” Associate Professor Colodro-Conde said.

“It is only by sharing data through these major, international collaborations that we can continue to unpick the highly complex relationship between our genes, brain structure and various disorders.”

The study was conducted within the ENIGMA consortium – a collaboration of more than 900 scientists from 45 counties investigating the genetic influences on the brain and the role of brain structure and function in disease.

About this neuroscience research article

Source:
University of New South Wales
Media Contacts:
Heidi Douglass – University of New South Wales
Image Source:
The image is credited to Tyler Ard, James Stanis, and Arthur Toga.

Original Research: Closed access
“The genetic architecture of the human cerebral cortex”. Perminder Sachdev et al.
Science doi:10.1126/science.aay6690.

Abstract

The genetic architecture of the human cerebral cortex

The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson’s disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder.

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