But lack of motivation and social withdrawal are also characteristic symptoms of the illness.
The study used a novel approach to map brain networks, according to Dr. Aristotle Voineskos, senior author on the paper. He goes on to say:
“Finding ways to help this particular group of people with schizophrenia is a priority as recovery is unlikely, even up to 20 years after the initial diagnosis. Social isolation, lack of work and relationships, and chronic disability are very common.”
Approximately one in five people with schizophrenia experience these negative symptoms in a pronounced way, says lead author Dr. Anne Wheeler, CAMH post-doctoral fellow. At this point, there is no treatment for negative symptoms, yet they have the greatest impact on a person’s daily functioning once the psychosis is managed.
Biological Brain-based Indicator Needed
The value of having a biological, brain-based indicator is that it may help identify this group of patients when they initially present for treatment of psychosis. Otherwise it can take years to determine social disability through clinical observation, says Dr. Voineskos.
The study involved magnetic resonance brain imaging (MRI) with 128 people with schizophrenia and 130 healthy individuals at two sites, and with 39 patients with bipolar disorder and 43 healthy individuals at a third site. Patients with bipolar disorder also experience psychotic symptoms but not negative symptoms, so these patients served as an additional comparison group.
The three sites were at CAMH, the Zucker Hillside Hospital in Glen Oaks, New York, and the Central Institute of Mental Health in Mannheim, Germany.
Researchers used a unique approach called network analysis to study the overall network density, or level of connectivity, in the brain.
“We found alterations in a number of relationships between brain regions among those with more severe schizophrenia compared with the other groups, including those with less severe schizophrenia. This provides strong evidence that schizophrenia is not just one brain disorder.”
The study also confirms previous research from his team showing changes in the white matter tissues connecting those same regions in the brain, among those with more severe schizophrenia.
These impaired networks are important to the brain processes related to negative symptoms and social function that patients experience, the authors write.
Based on these findings, the investigators are also funded by the U.S. National Institute of Mental Health to conduct a multi-centre study of a large number of people with schizophrenia to establish the full range of impairment in brain circuitry that predicts social impairment.
Through this research, specific brain circuits can be targeted to develop new therapeutic approaches for negative symptoms and social impairment. Such studies are now underway at CAMH using virtual reality technology and brain stimulation.