Some cases of schizophrenia may be caused by skull malformations, new research suggests.
The study was published Dec. 5 in the journal nature communicationsfocus on 22q11.2 deletion syndromea chromosomal disease in which a small portion of one copy of chromosome 22 is missing. (Humans typically carry around 23 pairs of shoes) chromosomecontaining one copy of chromosome 22 from each parent. )
The syndrome, which affects approximately 1 in 2,150 births, can affect different parts of the body and can cause heart abnormalities, immune disorders, cleft palates, and developmental delays. People with this syndrome have a 25% to 30% chance of developing schizophrenia during adolescence or early adulthood. research suggests. Other symptoms include: schizophrenia It can also cause psychosis, cause a disconnection from reality such as hallucinations, and disrupt people’s ability to maintain social relationships and express emotions.
This study suggests that the risk of schizophrenia may be due to malformations in the skull that restrict the growth of parts of the brain. And these malformations can be traced to a gene called Tbx1.
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“What’s interesting about Tbx1 is that it is poorly expressed in the brain, especially in the adolescent and adult brain,” said the study co-authors. Dr. Stanislav ZakharenkoDirector of the Department of Neural Circuits and Behavior in the Department of Developmental Neurobiology at St. Jude University said: statement. This means that the brain does not “turn on” Tbx1.
“Rather, it is expressed in the surrounding tissues: bone, cartilage, and vascular tissue,” Zaharenko said. “There is no possibility that Tbx1 directly affects the brain.”
To pinpoint Tbx1, Zakharenko and colleagues studied laboratory mice with and without the 22q11.2 deletion. With previous mice, I saw the following differences: cerebellum — The part of the brain involved in coordinating movement, maintaining posture, and learning new skills, among other cognitive functions. In the deletion mice, two of the cerebellar lobes were approximately 70% smaller.
This reduction in size made it more difficult for the mice to complete tasks that required them to learn movements, the experiments suggested. This difficulty is vestibulo-ocular reflex (VOR), a reflex that helps stabilize visual field during head movements. In humans, the lack of visual stabilization make it difficult to recognize people’s facesboth VOR and face recognition problems are common in schizophrenia.
Despite these observations in mice, the researchers saw nothing particularly unusual about the cellular composition of the undersized leaves or the way the cells formed. What they confirmed was that the skull, which houses that part of the brain, was malformed.
There should be a cozy “pocket” for that part of the cerebellum to grow into, but that pocket was much shallower than normal, so the tissue was crowded. The researchers revealed that the Tbx1 gene was found to be the problem because, without it, bone cells do not mature normally.
To see if people with 22q11.2 deletion syndrome have similar brain abnormalities, the research team performed magnetic resonance imaging (MRI) on 80 people with the disease and 68 people without. I looked at the scan. Similar to mice, people with this syndrome showed a clear reduction in the size of the same cerebellar lobes.
However, this reduction in size was “less severe” in humans than in mice, the researchers wrote in their paper. They still don’t know exactly why.
Although this line of research is still in its early stages, current data point to a potential “previously unrecognized” link between 22q11.2 deletion syndrome and schizophrenia.
Looking ahead, the researchers plan to further investigate how this mechanism may cause psychosis in the future through indirect effects on other parts of the brain connected to the cerebellum.
