Smokers at greater risk of schizophrenia and psychotic disorders

21 November 2018
Ananya Mandal, MD
News Medical Life Science

A team of researchers from University of Queensland have found that tobacco use is associated with an increased risk of psychotic disorders including schizophrenia.

The study titled “Evidence of a Causal Relationship Between Smoking Tobacco and Schizophrenia Spectrum Disorders,” was published in the latest issue of the journal Frontiers in Psychiatry.

A team of researchers from University of Queensland have found that tobacco use is associated with an increased risk of psychotic disorders including schizophrenia.

The study titled “Evidence of a Causal Relationship Between Smoking Tobacco and Schizophrenia Spectrum Disorders,” was published in the latest issue of the journal Frontiers in Psychiatry.

To assess if there was any association, the team used a Bradford Hill Framework which contains nine criteria that can link the exposure to outcome. Of these nine criteria, five were chosen to be highly relevant. All studies were conducted in high income countries. The participants in the studies were followed up for a minimum of 4 years to a maximum of 48 years.

Results showed that there was a six fold rise in risk of schizophrenia in heavy smokers as seen from the strength of association. Only one of the eight studies did not show a causal association between smoking and schizophrenia write the researchers. Overall there was a two-fold rise in risk of schizophrenia among smokers, the researchers write.

The authors of the study explain that there are around 5000 different chemicals in tobacco smoke but nicotine seems to be the main culprit here. There have been studies that have shown that nicotine is capable of altering the signal system of the brain mainly in the “dopaminergic, cholinergic, and glutamatergic neurotransmitter systems,” they explain. This could negatively influence brain maturation in teenagers and young adults. Further this could cause “strengthening of negative emotional changes and alterations in cognitive functioning,” in adolescents they add and this could possibly lead to mental ailments later in life.