Researchers have identified a change in brain activity that was specific to patients with psychotic illness but not their relatives. This change may reflect a "switch" that determines whether a person transitions from an at-risk state to full-blown illness, Alex Fornito says. (Credit: Jenny Spadafora/Flickr)

Why psychosis strikes some family members and not others

People with psychotic illness show similar brain changes to immediate family members who present no signs of illness.

These brain changes represent a marker of genetic risk of developing psychotic illnesses, such as schizophrenia, and could be targeted in the development of new treatments, researchers say.

“First-degree relatives of people with psychosis are at increased genetic risk of developing a psychotic illness,” says Alex Fornito, associate professor and deputy director of Clinical and Imaging Neuroscience at Monash University.

“We have found that people with psychosis and their unaffected first-degree relatives, who otherwise present no signs of illness, show similar brain changes when compared to healthy people.”

Even at the earliest signs of illness, patients show altered activity (when compared to healthy people) in a specific brain circuit that links a region deep in the brain called the striatum with the prefrontal cortex. This circuit plays an important role in attention, learning, and memory.

“The fact that we see the same brain changes in this group, in the absence of any overt signs of illness, points to a neural biomarker of risk for psychosis,” Fornito says.

“Patients who showed more severe changes in this circuit also showed more severe psychotic symptoms, providing a direct link between these brain changes and illness severity.”

For the study, published in JAMA Psychiatry, researchers examined 19 young people experiencing their first episode of psychotic illness and 25 of their unaffected parents or siblings. A group of 26 healthy unrelated participants was also recruited to draw comparison.

The researchers used magnetic resonance imaging (MRI) to map the activity of different brain systems.

Brain switch

Researchers identified a change in brain activity that was specific to patients but not their relatives. This change may reflect a “switch” that determines whether a person transitions from an at-risk state to full-blown illness, Fornito says.

“We know that activity in brain circuits linking the striatum and prefrontal cortex are heavily influenced by the neurotransmitter dopamine, which is a major target for all medications currently used to treat psychosis.

“The difficulty is that these drugs have rather diffuse effects on the brain, affecting many different systems. They also often have unpleasant side effects.

“Our findings point to a more specific treatment target. We are currently investigating whether we can selectively improve activity patterns in the affected brain circuits using non-invasive magnetic stimulation techniques. If successful, using these techniques in at-risk populations may help delay, minimize, or prevent the impact of psychosis onset.”

Source: Monash University

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