In people with a genetic predisposition for schizophrenia, having high intelligence may help protect them from developing the severe mental disorder, according to a new study by researchers at Virginia Commonwealth University (VCU) and Lund University in Sweden.
In fact, people with a lower IQ (intelligence quotient) than their siblings had the greatest risk for developing schizophrenia.
The research appears to contradict the popular belief that schizophrenia and brilliance are typically linked.
“If you’re really smart, your genes for schizophrenia don’t have much of a chance of acting,” said first author Kenneth S. Kendler, M.D., professor of psychiatry and human and molecular genetics in the Department of Psychiatry, VCU School of Medicine.
“What really predicted risk for schizophrenia is how much you deviate from the predicted IQ that we get from your relatives. 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.”
Just like those without the disease, people with schizophrenia vary widely in their intelligence levels. Kendler added that low IQ is one of many risk factors for schizophrenia.
For the study, researchers assessed the IQs of more than 1.2 million Swedish males (ages 18-to-20) born between 1951 and 1975. Schizophrenia-related hospitalization was tracked for 24 years until 2010. Subjects with a lower IQ than their siblings were at the greatest risk for developing schizophrenia.
Kendler noted that environmental factors that may lower IQ, such as intrauterine experience, childhood trauma, or early drug use, could contribute to the increased risk.
Having a high IQ, however, doesn’t completely eliminate the risk for schizophrenia. In fact, there are several well-known, brilliant and creative people who have suffered from schizophrenia, including math prodigy John Nash, whose story was made famous in the film “A Beautiful Mind.”
“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.
Schizophrenia is one of the most severe and rarest of the mental health disorders, occurring in about one in 100 people. Symptoms of the disease include hallucinations, delusions, paranoia, cognitive impairment, social withdrawal, self-neglect, and loss of motivation and initiative.
The study is published in the American Journal of Psychiatry’s online journal AJP.
Source: Virginia Commonwealth University