New brain imaging research has shown how different brain networks contribute to distinct sub-symptoms of schizophrenia — distinctions that are not recognizable from behavioral observations alone.
Study authors said the findings also support the emerging theory that schizophrenia is not a single disease but a complex assortment of neural circuit problems.
“For a long time, we’ve thought of brain imaging studies as mainly a way to corroborate or confirm aspects of brain function and pathology that we had already identified from studying a patient’s behavior,” said senior author Aysenil Belger, Ph.D., professor of psychiatry and psychology at the University of North Carolina School of Medicine.
“This approach, where we use brain imaging to dissect the specific neural pathways of complex syndromes, is very novel and important. The imaging can help us distinguish between the different brain networks that contribute to distinct sub-symptoms.”
Schizophrenia is a severe mental disorder affecting about one in 100 people. Historically, schizophrenia has been very difficult to diagnose and treat, in large part because it manifests differently in different people.
Belger and recent UNC graduate student Joseph Shaffer, Ph.D., created a map that shows how specific schizophrenia symptoms are linked to distinct brain circuits. They compared brain scans from more than 100 people with schizophrenia against brain scans from people with no psychiatric diagnoses.
The scans were acquired as part of a large multi-site national collaborative research project, the Biomedical Informatics Research Network. Researchers imaged participants during a non-invasive test in which subjects were asked to listen to simple tones and detect changes in pitch.
The analysis revealed that people with schizophrenia showed markedly less brain activity during detection of the tonal changes as compared to the control group, a difference that became more apparent as symptoms worsened.
The study’s most novel and striking findings emerged when researchers analyzed patterns of brain activity in patients with different types of schizophrenia symptoms.
Investigators focused on schizophrenia’s so-called “negative” symptoms, such as problems with speech, blunted emotions, lack of motivation, and an inability to experience pleasure. (“Positive” symptoms include delusions, thought disorders, and hallucinations.)
Negative symptoms are the hardest to treat with available medications and can make it difficult to hold a job or form relationships. A close analysis of the brain scans revealed vastly different neural circuitry behind problems that seem similar on the surface.
Brain scans helped to distinguish areas of the brain responsible for specific symptoms. For example, while a clinician may find it difficult to determine whether a patient’s stilted conversational manner is rooted in a lack of emotional connection or problems forming words, brain scans made it clear that particular symptoms were more closely associated with disruption in the brain’s emotional processing areas.
Scans also provided objective evidence that other areas of the brain were more closely associated with language and motor control.
“We were surprised by the degree to which these circuits were connected with different sub-symptoms, and by what was, in some cases, almost a complete lack of circuit overlap between these different sub-symptoms,” said Belger. Parsing these complex symptoms could help inform new treatment approaches for schizophrenia and other disorders.
“Many of these sub-symptoms are seen in other neuropsychiatric disorders, as well. Therefore, finding the neurological pathway or developing a treatment for that specific symptom could help to address multiple disorders,” Belger said.
Also, the findings could help improve the tools available for early detection of risk for schizophrenia and psychosis, which are typically not diagnosed until late adolescence.
Source: University of North Carolina