There has been a great deal of criticism surrounding the Intelligence Quotient (IQ) test, as studies have been unable to conclusively find that the metric actually has anything to do with predicting an individual’s likelihood of success in life. So is IQ completely useless? Maybe not. A new study has revealed that a higher IQ is connected to a lower risk of developing schizophrenia, even with a genetic predisposition. Kenneth Kendler of Virginia Commonwealth University was lead author of the paper, which was published in The American Journal of Psychiatry.
Schizophrenia is a severe mental disorder with symptoms that can manifest through abnormal social behavior, paranoid delusions, and auditory hallucinations. The disorder is largely caused by genetic factors, though drug use and emotional trauma may also play a role. This new study is the largest to date that explores the relationship between schizophrenia and intelligence.
“If you’re really smart, your genes for schizophrenia don’t have much of a chance of acting,” Kendler said in a press release.
The study analyzed the IQ scores of over 1.2 million Swedish men. The men were 18-20 years old at the time their IQ was measured, between 1979 and 1995. Any hospitalizations related to schizophrenia were tracked from 1986-2010. Kendler’s team found that there was a striking connection to schizophrenia diagnosis and IQ score, relative to the individual’s siblings.
“What really predicted risk for schizophrenia is how much you deviate from the predicted IQ that we get from your relatives,” Kendler explained. “If you’re quite a bit lower, that carries a high risk for schizophrenia. Not achieving the IQ that you should have based on your genetic constitution and family background seems to most strongly predispose for schizophrenia.”
Of course, though higher IQ may reduce the risk of schizophrenia, it does not mean that intelligent people are impervious to the disorder. The researchers point to the most famous instance of this: mathematician John Nash. Nash was awarded the Nobel Memorial Prize in Economic Sciences in 1994 for his work in game theory, which has widespread interdisciplinary implications. Nash’s life was portrayed by Russel Crowe in the movie A Beautiful Mind. It had actually been previously assumed that high intelligence would make one more susceptible to schizophrenia, though these results debunk that notion.
“The question is, might we see some upward bump at that high level of intelligence where really brilliant people have increased risk for the disease and we show no such trend,” Kendler said.
An unrelated study in September found that not only are 80% of schizophrenia cases caused by genetic factors, but there are actually eight genetically-distinct forms of the disorder. However, the current study doesn’t investigate how IQ relates to those disorders individually. That could potentially be an avenue for future research.