For years researchers have noted an unusual association between smoking and schizophrenia. Across multiple studies it was identified that people with schizophrenia were much more likely to smoke than people without the disease. New research may have finally solved the mystery while also paving the way for the development of new, more targeted treatments for several mental health conditions.

A meta-analysis of worldwide studies conducted in 2005 definitively showed what many doctors had been anecdotally noting for decades. Schizophrenia patients were much more likely to become heavy smokers than than those in the general population. In fact some studies found over 80 percent of those diagnosed with schizophrenia were smokers. There were many social and psychological hypotheses proposed to explain this strange anomaly, but none were ever sufficient.

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A new study published in Nature Medicine has not only revealed how smoking can normalize the impairments in brain activity associated with schizophrenia, but unlocks an entirely new field of drug research to combat the disease.

The study expanded on the recent discovery of a genetic mutation, labelled CHRNA5, that was identified as being associated with the cognitive impairments seen in schizophrenic patients. The scientists took mice with the CHRNA5 gene variant and discovered they displayed similar characteristics to those suffering from schizophrenia, such as an inability to suppress a startle response and an aversion to social interaction.

Using brain imaging technologies the research team discovered the mice with the CHRNA5 gene variant displayed symptoms of hypofrontality, a state of decreased blood flow in the prefrontal cortex of the brain. Hypofrontality is commonly thought to be a prominent cause of many symptoms of schizophrenia, as well as being associated with other psychiatric conditions including Bipolar Disorder and ADHD.

As well as identifying the role this gene variant plays in causing hypofrontality, the study examined how nicotine acted to restore normal activity to the prefrontal cortex. The researchers found that within one week of daily nicotine dosing the impaired brain activity in mice with schizophrenic characteristics had normalized.

"Since the repeated administration of nicotine restores normal activity to the prefrontal cortex, it could pave the way for a possible therapeutic target for the treatment of schizophrenia," says Uwe Maskos, the main author of the study.

The authors of the study also believe the research may have broad applications for novel drug development across the mental health field.

Source: University of Colorado Boulder, Institut Pasteur (via Eurekalert)