Subtle malformations in the shape of the thalamus in the brain are generally found in schizophrenic patients — and their healthy siblings appear to display the same abnormalities, according to a study published on June 6, 2007 in The Journal of Neuroscience.
Scientists at the Silvio Conte Center for the Neuroscience of Mental Disorders at Washington University School of Medicine in St. Louis performed MRI scans of the brains of 25 patients with schizophrenia, as well as their non-affected siblings. These scans were compared to those of 40 healthy volunteers and their siblings. A process that converts the two-dimensional images of the scan into three-dimensional models of brain anatomy, also known as high-dimensional brain mapping, was used to detect tiny differences in the anatomy of the brain.
“We’re interested in the thalamus because it has a lot of connections to the prefrontal cortex,” states Michael P. Harms, Ph.D., senior scientist at the Conte Center. ” In addition to psychosis, schizophrenia is characterized by other difficulties, such as issues with working memory and decreased cognitive performance. Those symptoms are believed to involve the cortex, and since the thalamus projects throughout the cortex, it’s conceivable abnormalities in the thalamus may be related to those symptoms.”
The thalamus transmits information from each sensory system (excepting smell) to the cortex while connecting many other structures throughout the brain. Because the same shape deformations of the thalamus were generally found in both individuals with schizophrenia and their healthy siblings, the investigators hope to focus the studies to determine whether these abnormalities could be biological markers for risk of the disease.
“We devised a mathematical approach and developed a shape score based on the differences in shape that we observed between those with schizophrenia and the healthy control subjects,” Harms explains. “Then we computed shape scores for the siblings of the schizophrenia patients. Their scores landed between the scores of the controls and the individuals with schizophrenia. The siblings had an intermediate degree of deformation in the thalamus.”
Just the size of a walnut, the thalamus has several sub-regions. When compared to control subjects, it was found that the front and back ends of the thalamus were deformed inward in patients with schizophrenia, and the same deformations were found to a lesser degree in their siblings.
Schizophrenia is a relatively common disease that affects approximately one percent of the general population. Even when the initial psychotic symptoms are treated with medication and psychotherapy, relapse is common. Even if no psychotic relapses occur, patients must remain on anti-psychotic medications for their entire lives.
“Early diagnosis and intervention with the most effective antipsychotic medications and psychotherapies may offer the best hope for patients with schizophrenia and their families.” stated co-investigator John G. Csernansky, M.D., the Gregory B. Couch Professor of Psychiatry and Neurobiology at the School of Medicine and director of the Conte Center. “This type of brain-structure analysis eventually may make it possible to start treatment for schizophrenia more quickly, perhaps even before full-blown psychotic symptoms, such as hallucinations and delusions, occur.”
According to the authors, shape changes in the thalamus may represent a biological marker, or endophenotype, for schizophrenia. But, until the symptoms of the illness can be linked definitively to the symptoms of the illness, they cannot be sure. They continue to investigate this topic now.
Thalamic shape abnormalities in individuals with schizophrenia and their nonpsychotic siblings
Harms MP, Wang L, Mamah D, Barch DM, Thompson PA, Csernansky JG.
The Journal of Neuroscience, vol. 27 (50), pp.13835-13842, Dec. 12, 2007. DOI:10.1523/JNEUROSCI.2571-07.2007
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Written by Anna Sophia McKenney