Infection links to schizophrenia

29 September, 2010

A breakdown in communication between brain regions that is suspected to lie behind symptoms of schizophrenia can be triggered by a maternal immune reaction to infection, latest University of Otago research shows.

In a world-first study, Department of Psychology researchers have found that disruption in long-range neural synchronisation in adult rats occurs following a one-off activation of their mother's immune system while pregnant with them.

PhD candidate and study lead author Desiree Dickerson says the findings, which appear in the latest edition of the Journal of Neuroscience, are an exciting step forward in understanding the brain mechanisms that underpin schizophrenia.

"There is a considerable body of evidence suggesting that changes in neural synchronisation may underlie a range of symptoms seen in schizophrenia.

"At the same time many studies have found that infection during early-to-mid pregnancy slightly increases the overall risk of children developing this illness as adults, with recent research implicating the mother's immune response.

"Our new study helps connect the dots between the maternal infection findings and the synchrony research. We show that a single activation of an immune response during pregnancy can lead to adult offspring showing disrupted communication between two key brain regions implicated in schizophrenia," said Dickerson.

In the study, adult rat offspring of mothers whose immune response was activated showed a marked decrease in long-range synchronised activity between the prefrontal cortex and hippocampus brain regions.

"Moreover, these offspring also displayed hallmark schizophrenia-like changes in their behaviour as they became adults, such as an abnormal startle response," she said.

Dickerson says effective communication between brain regions requires the coordinated or synchronised firing of populations of cells within the brain.

"This can be compared to a crowd performing a Mexican wave. Brain cells in individuals with schizophrenia are like people trying to produce the Mexican wave independently and with poor timing - the wave doesn't form cohesively and the message is distorted."

Up until now, there has not been a good developmental model for investigating why and how this synchronisation and desynchronisation occurs, she says.

"Importantly, this study has provided a chance to examine what happens in schizophrenia at a biological level that would otherwise be inaccessible. This will ultimately lead to better understanding and treatment of this severe mental illness."

Source: University of Otago