New clues reveal risk of psychotic illness

2013-09-09 13:33
New study finds brain offers clues that reveal risk of psychotic illness

People with psychotic illness show similar brain changes to immediate family members without any signs of illness, according to a new study published today in the journal JAMA Psychiatry.

Researchers found that these brain changes represent a marker of genetic risk of developing psychotic illnesses, such as schizophrenia.

The lead researcher says these genetic markers could be targeted in the development of new treatments that may help to reduce the risk of developing psychotic illness.

"First-degree relatives of people with psychosis are at increased genetic risk of developing a psychotic illness," said lead researcher, Associate Professor Alex Fornito, Deputy Director of Monash Clinical and Imaging Neuroscience in the School of Psychology and Psychiatry.

"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," he added.

Even at the earliest signs of illness, Fornito said patients showed altered activity (when compared to healthy people) in a specific brain circuit that links the striatum (a region deep in the brain) with the prefrontal cortex, and 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," noted Fornito.

"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," he explained.

The study examined 19 young people experiencing their first episode of psychotic illness, as well as 25 of their parents or siblings who presented no signs of illness. Another 26 healthy and unrelated participants were also recruited as a comparison group.

Using magnetic resonance imaging, or MRI, to map the activity of different brain systems, the research team found a change in brain activity that was specific to patients with psychotic illness, but not their healthy relatives.

Fornito said this change may reflect a 'switch' that determines whether a person transitions from an at-risk state to full-blown illness.

"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," Fornito explained.

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

"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."

The National Institutes of Health defines psychotic disorders as severe mental disorders that cause abnormal thinking and perceptions. People with psychoses lose touch with reality. Two of the main symptoms are delusions and hallucinations.

Schizophrenia is one type of psychotic disorder. People with bipolar disorder may also have psychotic symptoms. Other problems that can cause psychosis include alcohol and some drugs, brain tumors, brain infections, and stroke.

Treatment depends on the cause of the psychosis. It might involve drugs to control symptoms and talk therapy. Hospitalization is an option for serious cases where a person might be dangerous to himself or others.

SOURCE: JAMA Psychiatry, Functional Dysconnectivity of Corticostriatal Circuitry as a Risk Phenotype for Psychosis, Fornito A, Harrison BJ, Goodby E, et al. (published September 4, 2013). doi:10.1001/jamapsychiatry.2013.1976