A new study, conducted by researchers at Virginia Commonwealth University and Lund University of Sweden, shows that people with a genetic predisposition to schizophrenia may be protected against the disease if they have a high IQ. This contradicts the popular myth that schizophrenia is directly linked to brilliance.
“If you’re really smart, your genes for schizophrenia don’t have much of a chance of acting,” claims lead author Kenneth S. Kendler, who is a professor of psychiatry and human and molecular genetics at the VCU School of Medicine.
In the study, soon to be re-published in the American Journal of Psychiatry, the researchers gauged the IQ of 1.2 million Swedish males born between 1951 and 1975. Hospitalization due to schizophrenia was tracked for 24 years and ended in 2010.
Results demonstrated that those, whose IQ was lower than their siblings were significantly more likely to become schizophrenic.
“What really predicted risk for schizophrenia is how much you deviate from the predicted IQ that we get from your relatives,” noted Kendler. “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.”
While the effect is fairly robust, it does not completely rule out the possibility of schizophrenia in highly intelligent people. Many well-known figures in popular culture, such as the brilliant mathematician John Nash, made famous in the movie “A Beautiful Mind”, have demonstrated that even highly creative and intelligent people can suffer from schizophrenia.
“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,” said Kendler.
Original research paper: Kenneth S. Kendler et. al., 2014, the American Journal of Psychiatry, IQ and Schizophrenia in a Swedish National Sample: Their Causal Relationship and the Interaction of IQ with Genetic Risk. DOI: 10.1176.