An international research team, which included scientists from the University of Edinburgh, has found that a commonly used antibiotic may reduce the risk of schizophrenia in young individuals. By analyzing extensive healthcare data from Finland, the researchers discovered that adolescents prescribed the antibiotic doxycycline while receiving mental health services had a 30-35% lower chance of developing schizophrenia compared to those given other antibiotics.

Doxycycline, known as a ‘broad-spectrum’ antibiotic used for treating infections and acne, is believed to influence inflammation and brain development, potentially leading to this protective effect. Previous studies have indicated that doxycycline can reduce brain cell inflammation and impact synaptic pruning, a natural process in which the brain refines neural connections.

Excessive synaptic pruning has been associated with the onset of schizophrenia, a severe mental disorder characterized by hallucinations and delusional beliefs. The researchers described these findings as promising, suggesting the possibility of repurposing doxycycline, a widely used medication, as a preventive measure against severe mental illnesses.

Professor Ian Kelleher, the lead researcher and professor of child and adolescent psychiatry at the University of Edinburgh, emphasized the significance of these findings in potentially reducing the risk of schizophrenia in young people with mental health issues. While acknowledging that the study was observational and not a randomized controlled trial, he emphasized the need for further investigation into the protective effects of doxycycline and other anti-inflammatory treatments in adolescent psychiatry patients to prevent severe mental illnesses in adulthood.

The research was a collaborative effort involving the University of Edinburgh, the University of Oulu, University College Dublin, and St John of God Hospitaller Services Group, with funding provided by the Health Research Board. The study’s results have been published in the American Journal of Psychiatry.