Psychotic symptoms experienced by people with schizophrenia could be caused by a faulty “switch” in the brain, according to new research.
In a study published today in the journal Neuron, scientists at The University of Nottingham in the UK demonstrated that the severity of symptoms, such as delusions and hallucinations, is caused by a disconnect between two regions in the brain — the insula and the lateral frontal cortex.
The discovery could at some time form the basis for better, more targeted treatments for schizophrenia with fewer side effects, the researchers noted.
The four-year study, led by Professor Peter Liddle, M.D., Ph.D., and Dr. Lena Palaniyappan in the University’s Division of Psychiatry, centered on the insula region, a segregated “island” buried deep within the brain, which is responsible for seamless switching between the inner and outer world.
“In our daily life, we constantly switch between our inner, private world and the outer, objective world,” said Palaniyappan. “This switching action is enabled by the connections between the insula and frontal cortex. This switch process appears to be disrupted in patients with schizophrenia. This could explain why internal thoughts sometime appear as external objective reality, experienced as voices or hallucinations in this condition.”
This also could help explain the difficulties in “internalizing” external material pleasures, such as enjoying music or a social event, that result in “emotional blunting” in patients with psychosis, she said.
She explained that several regions of the brain are engaged when we are lost in thought or remembering a past event. However, when interrupted by a loud noise or another person speaking, we are able to switch to using our frontal cortex area of the brain, which processes this external information. With a disruption in the connections from the insula, such switching may not be possible, according to the researchers.
The research team used functional MRI imaging to compare the brains of 35 healthy volunteers with those of 38 schizophrenic patients. The results showed that while the majority of healthy patients were able to make this switch between regions, the schizophrenic patients were less likely to shift to using their frontal cortex.
The researchers explain that the insular and frontal cortex form a loop within the brain — the insular should stimulate the frontal cortex while the frontal cortex should inhibit the insula — but in patients with schizophrenia this system was found to be seriously compromised.
The results suggest that detecting the lack of a positive influence from the insula to the frontal cortex using fMRI could have a high degree of predictive value in identifying patients with schizophrenia, the researchers said.
Schizophrenia is one of the most common serious mental health conditions, affecting around 1 in 100 people. Its onset occurs most commonly in a patient’s late teens or early 20s, which can have devastating consequences for their future, the Nottingham scientists note.
Scientists remain unsure what causes schizophrenia, but believe it could be a combination of a genetic predisposition combined with environmental factors. Drug use is known to be a trigger — people who use cannabis, or stimulant drugs, are three to four times more likely to go on to develop recurrent psychotic symptoms, according to the researchers.
It is also believed that underdevelopment of the brain in the womb caused by complications in the mother’s pregnancy, as well as in early childhood linked to issues such as malnutrition could play a key part. Previous observations from this research group uncovered the presence of unusually smooth folding patterns of the brain over the insula region in patients, suggesting an impairment in the normal development of this structure in schizophrenia.
Today, treatment involves a combination of antipsychotic medications, psychological therapies and social interventions. Only one in five patients with schizophrenia achieve complete recovery. Many patients struggle to find a treatment that is 100 percent effective in managing their condition.
The researchers are also looking at a technique called TMS — transcranial magnetic stimulation — which uses a powerful magnetic pulse to stimulate the brain regions that are malfunctioning. Researchers believe that delivering a pulse to the frontal lobe could stimulate the insula and reset the switch.
Other treatment options could include the use of a compassion-based meditation therapy called mindfulness, which may have the potential to reset the switch, as well as promote physical changes within the brain. These ideas are in its early stages at present, but may deliver more focused treatment approaches in the longer term, researchers conclude.
Source: University of Nottingham