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Key points
- A new study analyzed brain scans in thousands of patients with schizophrenia and healthy controls.
- Patients and controls showed differences in brain asymmetries in two brain regions—one related to language, and the other to emotions.
Schizophrenia is a devastating mental health issue that affects about 1% of Americans. Its symptoms can be quite different from patient to patient. Common symptoms include hearing voices and other forms of hallucinations, delusions, paranoia, as well as problems with thinking, and incoherent speech. All these symptoms represent issues with brain functions such as speaking or thinking. Therefore, scientists have conducted many studies looking for changes in the structure of the brains of patients with schizophrenia compared to healthy volunteers, as this may be helpful in understanding the reasons for schizophrenia and potentially creating new ideas for better treatments.
One leading theory suggests that schizophrenia is related to a reduction of so-called hemispheric asymmetries in the language system. In almost all people, brain networks on the left side of the brain are controlling language. In schizophrenia, this leftward asymmetry may be reduced, which may be related to common language issues in patients, such as hearing voices that are not really there. While this is an intriguing theory, previous research studies have yielded very inconsistent results, possibly because the number of people tested in most studies was rather low.
A new study on brain asymmetries and schizophrenia
A new study by the ENIGMA consortium, now published in the journal PNAS, tackled this problem by conducting the largest-ever study on brain asymmetries in schizophrenia (Schijven et al., 2023). The international research team analyzed magnetic resonance imaging data from 5,080 patients with schizophrenia and 6,015 controls. Magnetic resonance imaging is a neuroimaging technique that uses magnets to create high-resolution pictures of the brain. It is commonly used in hospitals for diagnosing different disorders, such as tumors in the brain. In addition to that, it is commonly used in psychological and neuroscientific research in order to assess the brain structure of patients and healthy people.
The scientists compared asymmetries in the thickness of the cortex of the brain between patients with schizophrenia and controls. They found asymmetry differences between the two groups in two brain areas: the rostral anterior cingulate (a brain area related to emotion and cognitive control) and the middle temporal gyrus (a key area for language). Both effects were caused by a thinner cortex on the left side of the brain in patients with schizophrenia compared to controls. This finding is in line with idea that language lateralization is altered in schizophrenia as these changes in the structure of speech area may cause altered function of the speech network.
A further whole-brain analysis of asymmetries revealed that all together, 7% of the variation in brain asymmetries was associated with the status of the participants (schizophrenia patients or control). This suggests broader changes in asymmetries across the brain in schizophrenia that are not limited to language regions. Taken together, the findings of the study show how large-scale neuroscientific studies in patients with mental disorders can be very informative in understanding the potential reasons why patients experience certain symptoms. Further analyzing the brain regions identified in the study using modern neuroscientific and molecular methods may be helpful in understanding the mechanisms behind schizophrenia and finally creating better treatments for patients suffering from this agonizing disorder.
References
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