How do genes shape the structures in our brains? Study finds new links with ADHD and Parkinson’s

The human brain is a marvel of complexity. It contains specialized and interconnected structures that control our thoughts, personality and behavior.

The size and shape of our brains also play a crucial role in cognitive functions and mental health. For example, there is a slightly smaller hippocampus, the structure responsible for the regulation of memory and emotion often seen in depression. In dementia: atrophy of the hippocampus is associated with memory loss and cognitive decline.

Despite these insights, we have only scratched the surface of understanding the brain and its relationship to mental health.

Working with scientists around the world, we have conducted the world’s largest genetic study of the size of regional structures of the brain. This study is now published in Nature genetics.

We discovered hundreds of genetic variants that influence the size of structures such as the amygdala (the ‘processing center’ for emotions), the hippocampus and the thalamus (involved in movement and sensory signals).

We uncovered their potential overlap with genes known to influence the risk of certain developmental, psychiatric and neurological disorders.

More than 70,000 brains

To understand how the brain is linked to mental health, scientists like us are conducting large-scale scientific studies around the world.

These studies, involving thousands of volunteers, form the basis of modern biomedical research. They help us discover genes linked to brain size and mental health problems. This in turn can improve diagnostic precision and even pave the way for it personalized medicinewhich uses a person’s genetic test results to tailor treatments.

We screened the DNA and closely examined the magnetic resonance imaging (MRI) scans of more than 70,000 people in 19 countries. We wanted to find out whether there are specific genetic variants that influence differences in brain size between individuals.

What we found was breathtaking. Some of these genes appear to be active early in life, and many genes also increase the risk of conditions such as attention deficit hyperactivity disorder (ADHD) and Parkinson’s disease.

What have we discovered?

Brain-related disorders are common, with an estimated 40% of Australians experiencing a mental health disorder their lives.

Our genetic findings show that larger regional brain volumes (the size of specific parts of the brain) are associated with a higher risk of Parkinson’s disease. In comparison, smaller regional brain volumes are statistically linked to a higher risk of ADHD.

These insights suggest that genetic influences on brain size are fundamental to understanding the origins of mental disorders. And understanding these genetic links is crucial. It shows how our genes can influence brain development and the risk of mental illness.

By exploring shared genetic causes, we could one day develop treatments that address multiple conditions simultaneously, providing more effective support to individuals with different conditions. This is especially important in mental health, where it is common for someone to experience more than one disorder at the same time.

Our research also found that genetic effects on brain structure are consistent across people of both European and non-European descent. This suggests that certain genetic factors have stuck around throughout human evolution.

Bridging the gaps

Our research also lays the foundation for using genetic data to develop statistical models that predict disease risk based on a person’s genetic profile.

This progress could lead to population studies, identifying people at higher risk for specific mental disorders. Early intervention can then help prevent or delay the onset of these conditions.

In the future, our goal is to bridge the gap between genetics, neuroscience and medicine. This integration will help scientists answer critical questions about how genetic influences on brain structure influence behavior and disease outcomes.

Understanding the genetics of brain structure and mental health susceptibility can help us better prevent, diagnose and treat these conditions.

The concept of the ‘human brain’ first appeared in ancient Greece around 335 BC. The philosopher Aristotle described it as a radiator that kept the heart from overheating. Although we now know that Aristotle was wrong, the complexities of the brain and its connections to mental health remain largely mysterious even today.

As we continue to unlock the genetic secrets of the brain, we come closer to unraveling these mysteries. This type of research has the potential to transform our understanding and treatment of mental health.

This article is republished from The conversation under a Creative Commons license. Read the original article.