Common Antibiotic Doxycycline May Lower Schizophrenia Risk

Research published in the American Journal of Psychiatry indicates that the commonly prescribed antibiotic doxycycline may reduce the risk of developing schizophrenia in some young individuals. The study highlights a significant finding: patients receiving doxycycline through adolescent mental health services showed a 30–35% lower risk of later developing schizophrenia compared to those treated with other antibiotics.

The research was conducted by a team from the University of Edinburgh, in collaboration with the University of Oulu and University College Dublin. They utilized advanced statistical modeling to analyze data from over 56,000 adolescents attending mental health services in Finland who had been prescribed antibiotics.

Understanding the potential for existing medications to serve as preventive measures against severe mental illness is crucial, especially as schizophrenia typically manifests in early adulthood. It is often characterized by hallucinations and delusional beliefs.

The researchers discovered that adolescents treated with doxycycline had a significantly reduced risk of developing schizophrenia. This protective effect is thought to be associated with the drug’s ability to influence inflammation and brain development. Doxycycline is a broad-spectrum antibiotic widely used to treat infections and acne. Earlier studies suggested that it might reduce inflammation in brain cells and affect synaptic pruning, a natural process in which the brain refines its neural connections. Excessive synaptic pruning has been linked to the onset of schizophrenia.

The analysis carefully considered various factors to ensure that the reduced risk was not simply a result of treating conditions like acne instead of infections. The findings indicate that the differences in outcomes were unlikely due to unaccounted variables between the groups.

Professor Ian Kelleher, the study’s lead and a Professor of Child and Adolescent Psychiatry at the University of Edinburgh, remarked on the implications of the findings. He noted that as many as half of those who go on to develop schizophrenia had previously attended child and adolescent mental health services for other issues. Currently, there are no known interventions that can effectively reduce the risk of developing schizophrenia in these vulnerable populations, making these findings particularly promising.

Despite the potential benefits, the study’s observational nature means that definitive conclusions about causality cannot be drawn. Professor Kelleher emphasized the importance of further investigation into the protective effects of doxycycline and other anti-inflammatory treatments for adolescent patients. This research could lead to new strategies for reducing the risk of severe mental illness in adulthood.

For those interested in exploring the study further, more information can be found in the American Journal of Psychiatry, DOI: 10.1176/appi.ajp.20240958.