Irving Gottesman is the winner of the 2013 Grawemeyer Award for Psychology. Over the past several decades, Gottesman’s work on the genetic and environmental factors that contribute to schizophrenia and other mental disorders has changed the way scientists classify the condition.

Gottesman is currently the retired Irving and Dorothy Bernstein professor of adult psychiatry and current senior psychology fellow at the University of Minnesota. He also is Sherrell J. Aston professor of psychology emeritus at the University of Virginia.

When Gottesman began his research in the 1960s, not much was known about schizophrenia. Many thought it was caused by so-called “cold mothers” who didn’t show their children enough love. But with his colleague James Shields, and through studies on identical and fraternal twins, Gottesman disproved that theory.

“When geneticists or people like me, genetically-minded psychologists, got into the act, we could clearly demonstrate that the concordance rate for identical twins was so much higher than the rate in fraternal twins that you had to infer a genetic factor or factors of some sort,” he said.

So he knew there had to be some genetic traits shared by the identical twins that combined with environmental factors to predispose them to schizophrenia. His theory—the polygenic threshold theory—was that both genes and environmental factors cause the disorder.

“There are families of genes which in total predispose you toward developing schizophrenia, but they only predispose you,” he said. “It takes some other element in this stew to throw you over the threshold into a clear clinical case of schizophrenia.”

This led to what Gottesman calls “endophenotypes:” the idea that there are discernable and measurable traits in people without obvious symptoms of schizophrenia.

Gottesman also undertook pioneering work in Denmark. The country has a national health care system, which meant that there were only state-run psychiatric facilities and Gottesman could access information about people who had been admitted. He analyzed 2.7 million people and found that Danes with both a mother and father who had been treated for schizophrenia were significantly more likely to develop symptoms of the disease than Danes with one or no parents treated for schizophrenia.

Gottesman’s work has implications for numerous other diseases, including bipolar disease and alcoholism.

“We see it in almost all disorders where there is a genetic component,” he said.

One of his models of complicated genetic disorders predicts “a ballet choreographed interactively over time among genotype, environment and what are now called epigenetic factors,” he said. “And all of these things added together give you the particular phenotype of interest.

As the winner of the Grawemeyer, Gottesman will accept his $100,000 award next year in Louisville.

The Grawemeyer Awards for World Order and Music Composition were announced earlier this week.