Genetic risk for schizophrenia is connected to reduced IQ

May 16, 2013, Elsevier

The relationship between the heritable risk for schizophrenia and low intelligence (IQ) has not been clear. Schizophrenia is commonly associated with cognitive impairments that may cause functional disability. There are clues that reduced IQ may be linked to the risk for developing schizophrenia. For example, reduced cognitive ability may precede the onset of schizophrenia symptoms. Also, these deficits may be present in healthy relatives of people diagnosed with schizophrenia.

In a remarkable new study published in Biological Psychiatry, Dr. Andrew McIntosh and his colleagues at the University of Edinburgh provide new evidence that the for schizophrenia is associated with lower IQ among people who do not develop this disorder.

The authors analyzed data from 937 individuals in Scotland who first completed IQ testing in 1947, at age 11. Around age 70, they were retested and their DNA was analyzed to estimate their genetic risk for schizophrenia.

The researchers found that individuals with a higher genetic risk for schizophrenia had a lower IQ at age 70 but not at age 11. Having more schizophrenia risk-related gene variants was also associated with a greater decline in lifelong cognitive ability.

"If nature has loaded a person's genes towards schizophrenia, then there is a slight but detectable worsening in cognitive function between childhood and old age. With further research into how these genes affect the brain, it could become possible to understand how genes linked to schizophrenia affect people's cognitive function," said McIntosh.

These findings suggest that common genetic variants may underlie both cognitive aging and risk of schizophrenia.

"While this study does not show that these common gene variants produce schizophrenia per se, it elegantly suggests that these variants may contribute to declines in intelligence, a clinical feature associated with schizophrenia," commented Dr. John Krystal, Editor of Biological Psychiatry. "However, we have yet to understand the development of cognitive impairments that produce disability in young adulthood, the period when schizophrenia develops for many affected people."

Clearly, more research is necessary, but this new study adds to the growing and substantial effort to understand how the gene variants that contribute to the development of schizophrenia give rise to the cognitive disability commonly associated with it.

Explore further: Schizophrenia genes increase chance of IQ loss

More information: The article is "Polygenic Risk for Schizophrenia Is Associated with Cognitive Change Between Childhood and Old Age" by Andrew M. McIntosh, Alan Gow, Michelle Luciano, Gail Davies, David C. Liewald, Sarah E. Harris, Janie Corley, Jeremy Hall, John M. Starr, David J. Porteous, Albert Tenesa, Peter M. Visscher, and Ian J. Deary (doi: 10.1016/j.biopsych.2013.01.011). The article appears in Biological Psychiatry, Volume 73, Issue 10 (May 15, 2013)

Related Stories

Schizophrenia genes increase chance of IQ loss

February 21, 2013
People who are at greater genetic risk of schizophrenia are more likely to see a fall in IQ as they age, even if they do not develop the condition.

Schizophrenia: A disorder of neurodevelopment and accelerated aging?

March 6, 2013
Many lines of evidence indicate that schizophrenia is a disorder of neurodevelopment. For example, genes implicated in the heritable risk for schizophrenia are also implicated in the development of nerve cells and their connections. ...

The mysterious GRIN3A and the cause of schizophrenia

March 14, 2013
Since the 1960s, psychiatrists have been hunting for substances made by the body that might accumulate in abnormally high levels to produce the symptoms associated with schizophrenia. In particular, there was a search for ...

Does immune dysfunction contribute to schizophrenia?

October 10, 2012
A new study reinforces the finding that a region of the genome involved in immune system function, called the major histocompatibility complex (MHC), is involved in the genetic susceptibility to schizophrenia.

Virus and genes involved in causation of schizophrenia

March 8, 2013
For the first time, an international team of researchers has found that a combination of a particular virus in the mother and a specific gene variant in the child increases the risk of the child developing schizophrenia.

Scientists unpack testosterone's role in schizophrenia

April 26, 2013
Testosterone may trigger a brain chemical process linked to schizophrenia but the same sex hormone can also improve cognitive thinking skills in men with the disorder, two new studies show.

Recommended for you

Intensive behavior therapy no better than conventional support in treating teenagers with antisocial behavior

January 19, 2018
Research led by UCL has found that intensive and costly multisystemic therapy is no better than conventional therapy in treating teenagers with moderate to severe antisocial behaviour.

Babies' babbling betters brains, language

January 18, 2018
Babies are adept at getting what they need - including an education. New research shows that babies organize mothers' verbal responses, which promotes more effective language instruction, and infant babbling is the key.

College branding makes beer more salient to underage students

January 18, 2018
In recent years, major beer companies have tried to capitalize on the salience of students' university affiliations, unveiling marketing campaigns and products—such as "fan cans," store displays, and billboard ads—that ...

Inherited IQ can increase in early childhood

January 18, 2018
When it comes to intelligence, environment and education matter – more than we think.

Modulating molecules: Study shows oxytocin helps the brain to modulate social signals

January 17, 2018
Between sights, sounds, smells and other senses, the brain is flooded with stimuli on a moment-to-moment basis. How can it sort through the flood of information to decide what is important and what can be relegated to the ...

Baby brains help infants figure it out before they try it out

January 17, 2018
Babies often amaze their parents when they seemingly learn new skills overnight—how to walk, for example. But their brains were probably prepping for those tasks long before their first steps occurred, according to researchers.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.