Neuroscientists from the St. Jude Children's Research Hospital (USA) have found that patients can be eliminated from "voices in the head" with the help of small RNA molecules (microRNAs) contained in a specific area of the brain. The scientists presented their findings in an article published in the journal Nature Medicine.
Schizophrenia is a serious mental disorder in which there is a disintegration of the human personality and a decrease in intelligence. The thoughts of patients often turn into delirium, it seems to them that someone is following them, and ordinary everyday problems are seen as complex conspiracy theories. One of the most frightening symptoms is auditory hallucinations, which are inherent not only in this disorder, but also in many others. It seems to the patient that someone is talking to him, and the voice comes from his own head. He can simply comment on a person's actions or encourage him to do bad things.
Despite the beliefs of some people who believe that these voices belong to supernatural forces, and exorcism rituals will help get rid of them, schizophrenia and its symptoms are just the result of a malfunction of the brain. According to some researchers, the mysterious voice that a sick person hears is in fact his own thoughts, although it seems to the patient that these thoughts do not belong to him. The reason for this phenomenon may be a malfunction in the activity of neural connections, for example, the connections of nerve fibers connecting the thalamus with the auditory cortex of the brain. It is this disorder that is associated with auditory hallucinations. As scientists have shown in mice, the chain malfunction is due to the 22q11DS mutation. As a result, Di Georg's syndrome develops - a rare congenital disease in which thymus development is impaired,dysfunction of the immune system occurs due to a sharp decrease in the population of T-lymphocytes. In 23-43 percent of cases, this mutation leads to the development of schizophrenia, accompanied by auditory hallucinations. This symptom can be treated with antipsychotics.
The problem, however, is that antipsychotic drugs that act on dopamine production have serious side effects. One of them is neuroleptic malignant syndrome, muscle rigidity, fever (hyperthermia), and mental disorders. Complications can affect various organ systems and even lead to death.
Thalamus
Photo: Wikipedia
How can a person be cured of "voices in the head", bypassing the risks associated with antipsychotics? In their research, the scientists analyzed a case of auditory hallucinations in a mouse model, although the animals themselves do not suffer from such a disorder. The researchers used mice with the 22q11DS mutation. In these animals, the long arm of chromosome 22 lacks a central region of DNA. In this case, the body loses the Dgcr8 gene. It has been shown that its absence in patients with Di Georg's syndrome leads to impaired signal transmission from the thalamus to the auditory cortex of the cerebral hemispheres. Normally functioning Dgcr8 provides the synthesis of specific microRNAs - small non-coding RNA molecules (18-25 nucleotides in length). Compounds belonging to this class inhibit the activity of a particular gene.
Promotional video:
If the Dgcr8 gene becomes inactive as a result of mutation, microRNAs stop being formed. As a result, there is no suppression of the expression of a gene responsible for the synthesis of a protein called the dopamine D2 receptor.
Dopamine receptors are proteins found in the membrane of neurons. The neurotransmitter dopamine binds to them, which is released by neurons into the synaptic cleft. The D2 receptor, after contact with dopamine, participates in reactions with other molecules, regulating various processes in the human nervous system. An excess of it, like a deficiency, leads to serious illness.
So, if the dopamine D2 receptor accumulates in the thalamus, then the neural circuit begins to behave incorrectly. For example, insufficient pre-pulse inhibition (PPI) occurs. In this case, there is no decrease in the motor response of the body to a strong sharp stimulus in the presence of a weak preliminary stimulus (pre-pulse). In other words, a person cannot be prepared for strong irritation (for example, a sharp loud sound) if first exposed to a weak one. Insufficient PPI is seen in schizophrenia, panic disorder, and schizotypal personality disorder.
John Nash - mathematician-economist with schizophrenia and auditory hallucinations
Photo: Elke Wetzig / Wikipedia
Scientists were able to confirm the connection of disturbances in neural circuits associated with auditory hallucinations with a lack of a special type of microRNA - miR-338-3p. Researchers used microinjections to inject these molecules into thalamic neurons, as a result of which they were able to restore normal activity of neuronal fibers between the thalamus and the auditory cortex. An insufficient amount of miR-338-3p in schizophrenic patients is the reason for an increase in the concentration of the mediator in the neurons of the auditory part of the thalamus.
It was found that an increase in the level of microRNA restores the normal functioning of the neuronal circuit, reducing the production of the dopamine D2 receptor. According to the researchers, miR-338-3p in the future may become the basis for a new class of antipsychotics that act more purposefully and with fewer side effects. Those suffering from auditory hallucinations can be saved through science, not exorcism.
Alexander Enikeev