Faulty brain processing of new information underlies psychotic delusions, finds new research


25-06-2020
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Problems in how the brain recognizes and processes novel information lie at the root of psychosis, researchers from the University of Cambridge and King’s College London have found. Their discovery that defective brain signals in patients with psychosis could be altered with medication paves the way for new treatments for the disease.

The results, published in the journal Molecular Psychiatry, describe how a chemical messenger in the brain called dopamine ‘tunes’ the brain to the level of novelty in a situation, and helps us to respond appropriately - by either updating our model of reality or discarding the information as unimportant. 

The researchers found that a brain region called the superior frontal cortex is important for signaling the correct degree of learning required, depending on the novelty of a situation. Patients with psychosis have faulty brain activation in this region during learning, which could lead them to believe things that are not real.

“Novelty and uncertainty signals in the brain are very important for learning and forming beliefs. When these signals are faulty, they can lead people to form mistaken beliefs, which in time can become delusions,” said Dr Graham Murray from the University of Cambridge’s Department of Psychiatry, who jointly led the research.

In novel situations, our brain compares what we know with the new information it receives, and the difference between these is called the ‘prediction error’. The brain updates beliefs according to the size of this prediction error: large errors signal that the brain’s model of the world is inaccurate, thereby increasing the amount that is learned from new information.

Psychosis is a condition where people have difficulty distinguishing between what is real and what is not. It involves abnormalities in a brain chemical messenger called dopamine, but how this relates to patient experiences of delusions and hallucinations has until now remained a mystery. 

The new study involved 20 patients who were already unwell with psychosis, 24 patients with milder symptoms that put them at risk of the condition, and 89 healthy volunteers. 

Participants were put into a brain scanning machine called a functional MRI and asked to play a computer game. This allowed the researchers to record activity in the participants’ brains as they engaged in situations with a potential variety of outcomes.

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Reproduced courtesy of the University of Cambridge

 

The University of Cambridge is acknowledged as one of the world's leading higher education and research institutions. The University was instrumental in the formation of the Cambridge Network and its Vice- Chancellor, Professor Stephen Toope, is also the President of the Cambridge Network.

University of Cambridge (cam.ac.uk)