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Smoking activates the schizophrenia gene
Last reviewed: 01.07.2025
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Smoking helps express one of the genes responsible for brain architecture; some variants of this gene increase the likelihood of developing schizophrenia, so if they are present, smoking becomes a risk factor for this disease.
Since it became known about the hereditary nature of schizophrenia, scientists have not abandoned attempts to find the genetic causes of the disease. It cannot be said that these attempts are unsuccessful, but the set of mutations that can lead to schizophrenia is growing every day, and it is extremely difficult to single out the main one in some main gene.
When studying the genetic causes of schizophrenia, the frequencies of dangerous gene variants in healthy people and those with it are usually compared. Scientists from the universities of Zurich (Switzerland) and Cologne (Germany) added an electroencephalographic test to this, which allows us to see how the brain processes sound signals. A healthy person can single out one, the most important, sound from many, and discard the rest as unnecessary noise. In schizophrenia, this ability is lost: the brain loses the ability to filter acoustic signals and eventually drowns in a stream of information. However, in healthy people, such processing of sound information is expressed differently: some do it better, some worse. By comparing such brain activity with the presence of a particular form of the gene, we can say what role this gene plays in the development of schizophrenia.
In this case, the researchers were primarily interested in the TCF4 gene, which codes for one of the transcription factors. This protein is involved in early brain development, and some variant forms of this gene are thought to have a less-than-favorable effect on the developing brain. In addition, TCF4 activity is not necessarily limited to the early stages of an organism's life. The experiment involved 1,800 people. It is worth noting that the researchers took into account the fact that there are many smokers among schizophrenics, and therefore paid special attention to the connection between the disease and the intensity of smoking.
As scientists write in the journal PNAS, the TCF4 gene did affect the brain's ability to filter sound information: some forms of TCF4 were accompanied by a deterioration in this brain function and were found primarily in patients with schizophrenia. But the researchers also noted that smoking made the situation much worse. If the owner of a dangerous form of the TCF4 gene also smoked, his brain showed a much worse result in processing the acoustic signal.
Here, according to scientists, we are faced with a common situation when environmental conditions limit or, on the contrary, help a gene to manifest itself. The results obtained should help in preventing the disease: if a smoker has the first symptoms of schizophrenia, and at the same time he is unlucky with the TCF4 gene, it is in his interests to quit smoking at all costs.
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