New study finds a genetic link between smoking and schizophrenia

It’s well known that most people with schizophrenia are also smokers, with more than 65 per cent of schizophrenics found to be users of tobacco products compared to about 20 per cent of the general population. But the connection between the two has been a point of conjecture, up until now, as a new study has found a genetic link between smoking and schizophrenia.

An international effort on the part of researchers from the United States, the Netherlands and the University of Toronto in Canada, the study used a psychiatric genome-wide association study to search through complete sets of DNA from thousands of samples in order to locate connections between genetic traits associated with schizophrenia and nicotine dependency, both of which have been shown to have genetic associations. Researchers found multiple genes related to both conditions, which supported two different but related conclusions.

On the one hand, most of the genes strongly connected to schizophrenia were not found to directly contribute to smoking behaviours in patients – indicating that one of the reasons why so many schizophrenics smoke is to self-medicate by suppressing their psychotic symptoms and improving their cognitive functioning with the use of nicotine, an explanation that has been suggested for some time by health experts.

On the other hand, genetic markers showed that the presence of schizophrenia and nicotine dependency are characterized by similar functioning of the brain’s neurotransmitters and communications between neurons, a result which indicates that smoking is a genetic risk factor for schizophrenia. “Our results supported the self-medication hypothesis. We also found evidence that schizophrenia and ND share some genetic liability,” say the study’s authors.

The Canadian Mental Health Association just concluded Mental Health Week, designated as the first week in May, with events across the country encouraging Canadians to “Get Loud” in support of mental health.

The week kicked off with a written statement from Prime Minister Justin Trudeau, who said that all Canadians need to help change the way society views mental health issues. “We all have a responsibility to raise our awareness about mental health. We must actively encourage honest and open conversations –in our homes, our workplaces, and our communities– about what mental health is and what we can do to increase our collective well-being,” said the statement.

Mr. Trudeau acknowledged all those who have spoken out publicly about their own struggles with mental health, including his own mother, Margaret Trudeau, saying, “They are true examples of courage, bravery, and resilience. Their stories help us all become more understanding, more compassionate, and more empathetic.”

Schizophrenia, a mental illness that includes symptoms of hallucinations, delusions and confused thinking, affects about one per cent of the population. While the cause is not fully understood, it’s believed to be rooted in both genetic and environmental factors, with an onset between the ages of 18 and 25 in men and between 25 and 35 in women. People who experience schizophrenia are at a higher risk for suicide -an estimated 20 to 40 per cent have attempted suicide at one time and five per cent having completed suicide. The disease is treated with antipsychotic medication and counseling.

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