Brain cells stuck in the layer below cortex could cause schizophrenia, Australian scientists say.
Prof Cyndi Shannon Weickert and her team from Neuroscience Research Australia, Schizophrenia Research Institute and UNSW have found that in people with schizophrenia, brain cells destined for the cortex - the outer part of the brain associated with thinking and other cognitive abilities - could get trapped in the layer below.
"We think brain cells might be trapped while in the process of migrating to the cortex while the brain develops. This process of neuronal migration to the cortex doesn't stop at birth. It's robust in infants and may continue in teenage years and beyond," she says.
"This could mean that parts of the cortex do not receive the full complement of neurons for thinking and reasoning to work properly in people with schizophrenia." she says.
The team looked at the brains of 29 people with schizophrenia and 37 healthy controls - the largest group of subjects used in a study like this so far.
They found that people with schizophrenia had many more neurons in the white matter layer below the cortex than the healthy controls. They also found evidence that this increased number of neurons in the white matter is linked with a lack of inhibitory neurons (called interneurons) in the cortex.
"We know that brain development is derailed somehow in people with schizophrenia, and this study helps us understand how," says Prof Shannon Weickert.
"In particular, it helps us understand why interneurons in the cortex, which are so important for coritical communication and thinking, might not function as well in people with schizophrenia."
The next step of the research is to understand why these neurons are failing to complete their journey to the cortex.
"Contrary to common dogma, we suspect there are new neurons arriving in the cortex well after birth, maybe even into the teenage years," says Prof Shannon Weickert.
"If that's the case, then maybe we can develop a therapy that encourages the neurons to keep moving to the finish line. Our hope is that this would reduce symptoms or even prevent schizophrenia from developing at all."
The paper is published in Biological Psychiatry