Can a High IQ Shield You From Schizophrenia?
High intelligence is often claimed to be linked to a higher risk of schizophrenia, but a recent study published in the American Journal of Psychiatry suggests that may not be true. In fact, high intelligence could potentially halt the development of schizophrenia, particularly in people already predisposed to the condition.
A collaboration between US and Swedish researchers claims that intelligence quotient, better known as IQ, is an important “moderator” in the development of schizophrenia, but the link works opposite of previous assumptions.
“If you’re really smart, your genes for schizophrenia don’t have much of a chance of acting,” said first author Kenneth S. Kendler, professor of psychiatry and human and molecular genetics at Virginia Commonwealth University.
The study used data from a long-term study of more than 1.2 million Swedish males born between 1951 and 1975. These men registered in the Military Conscription Register and participated in a study assessing their IQ between the ages of 18 and 20 and late adolescence. These men were also tracked for a history of schizophrenia-related hospitalization until 2010.
According to the findings, low IQ is among numerous other factor contributing to the development of schizophrenia, including fetal experience, childhood trauma, or early drug use. However, there was also a large variation in the IQs of the individuals with schizophrenia.
“What really predicted risk for schizophrenia is how much you deviate from the predicted IQ that [you] get from your relatives,” Kendler said. “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.”
The findings show a 1-point decrease in IQ is associated with a 3.8 percent increase in the risk of schizophrenia, and the effect was strongest within families. However, the researchers say “[schizophrenia] nearly disappears at the highest IQ level.”