The genetic component in understanding and treating mental illness

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Schizophrenia is a chronic neurological brain disorder that affects millions of people around the world. Although diagnosis and treatments have come a long way, it wasn’t until the last 20 to 30 years that scientists discovered certain genes that put people at risk for mental illness. How does this new science impact treatment, and why do mental disorders run in some families but not others? And how can our environment trigger these illnesses? 

KCRW’s Jonathan Bastian talks about destigmatizing schizophrenia and how mapping the human genome has changed people’s understanding of mental illness. He’s joined by Daniel Weinberger, Johns Hopkins University psychology professor and director and CEO of the Lieber Institute for Brain Development. 

The following interview excerpts have been abbreviated and edited for clarity

KCRW: What role does the environment play in triggering mental disorders? 

Daniel Weinberger: “Environments are very important. The problem with studying the environment is it’s much more difficult to get your hands around it. Genes are biological entities, they're definable, they're bound. It's very easy, relatively speaking, to study them. The problem with the environment, and I always cite Paul Simon's lyrics when he said, ‘One man's ceiling is another man's floor,’ as the environment is critically dependent on who you are.  So in the last five seconds of an NBA game, Michael Jordan, Magic Johnson, people like that always wanted that ball. Other people never wanted that ball in the last five seconds, it was too much of an expectation. 

People have tremendously diverse experiences of the same environment, and that's presumably because our genomes have something to do with how the environment feels to us. So it's much harder to study the environment. 

One of the things we now know about almost all mental illnesses is that there are components of these illnesses that start very early in life, maybe even before postnatal life, certainly for schizophrenia, for autism, for ADHD. As we've been studying these genes, we've discovered that many of these genes seem to be turned on during prenatal life, meaning they have something to do with the original wiring of the brain, and they presumably set up a developmental trajectory that deviates towards the expression of these disorders. 

… To give this some visual sense, think about when you go bowling and you try to bowl a strike. The idea is to get the ball to cross over the second arrow, in from the right, about 10 feet up from the fore line in the alley. If it crosses that arrow at the right angle with the right speed, by the time it gets to the pins, all the way down the alley, it's no longer where it started at that arrow. It now has a trajectory that slowly but surely takes it towards the strike zone and it's a strike. That's a perfect development or trajectory. 

What if early in development, you're an inch off that arrow? By the time you get to the end of the alley, which is 20 years of human development, the vagaries of dust and other things on that arrow, by the time the ball gets to the pins, it's not one inch off the strike zone, it's about four inches off the strike zone. And if there's a lot of dust on that alley, it may be further off the strike zone. At the same time, dust on the alley, in other words the environmental experience, is perhaps very good parenting, very good experiences at school. Those can actually deviate the ball back to the strike zone. This is how we talk about genes and the environment interacting with each other. 

Human development is very complicated. There's a great deal going on, but genes are the blueprint for building brains and building the resources that brains have to develop in the context of extremely complicated human environments. The human being is the only animal that has this very protracted, postnatal period of development before it can function independently because the human brain evolved based on early programs of development that interact with the environment. It's critically dependent on how you set up the developmental capabilities to learn and grow based on your environmental experience. 

So our assumption is that mental illnesses involve a deviation from that early trajectory, that either continues to deviate, so when it gets to the pins, it's far from a strike or manages to find a way back over that developmental period towards the strike zone. But the genes set up the trajectory from early in life.”



  • Daniel Weinberger - Professor of Psychiatry and Behavioural Sciences, Johns Hopkins University and Director and CEO, Lieber Institute for Brain Development - @Dr_Weinberger


Andrea Brody