A new study published in the American Journal of Psychiatry indicates that the commonly prescribed antibiotic doxycycline may significantly reduce the risk of developing schizophrenia in some young people. Researchers from the University of Edinburgh, in collaboration with the University of Oulu and University College Dublin, found that adolescents receiving doxycycline as part of their treatment were 30–35% less likely to develop schizophrenia in adulthood compared to their peers treated with other antibiotics.
The research utilized advanced statistical modeling to analyze large-scale health care register data from Finland, focusing on over 56,000 adolescents who had received antibiotic treatment through mental health services. The study’s findings suggest a potential for repurposing doxycycline as a preventive measure against severe mental illness.
Schizophrenia, a serious mental disorder often emerging in early adulthood, is characterized by hallucinations and delusional beliefs. Understanding methods to prevent this condition has become increasingly vital, especially given that approximately half of those who develop schizophrenia had previously attended child and adolescent mental health services for other issues.
Research Findings and Implications
The researchers postulated that the protective effects observed could be linked to doxycycline’s ability to reduce inflammation and influence brain development. Doxycycline is a broad-spectrum antibiotic frequently used to treat infections and acne. Previous studies have indicated its potential to lower inflammation in brain cells and impact synaptic pruning, a natural process crucial for developing healthy neural connections. Excessive synaptic pruning has been associated with the onset of schizophrenia.
Notably, the researchers found that the lower risk of developing schizophrenia among those treated with doxycycline could not be simply attributed to the fact that some patients were treated for acne instead of infections. Further analysis ruled out other hidden differences that might account for the varying outcomes.
Professor Ian Kelleher, the lead researcher and Professor of Child and Adolescent Psychiatry at the University of Edinburgh, emphasized the significance of these findings, stating, “At present, though, we don’t have any interventions that are known to reduce the risk of going on to develop schizophrenia in these young people. That makes these findings exciting.”
Future Research Directions
While the study is observational and does not establish a direct causal link, it serves as an important signal for further investigation into the protective effects of doxycycline and other anti-inflammatory treatments. The findings may open new avenues in adolescent psychiatry, offering potential strategies to mitigate the risk of developing severe mental illnesses in adulthood.
As research continues, the implications for clinical practice could be considerable, emphasizing the need for effective preventive measures for vulnerable populations. The study highlights the importance of exploring existing medications for new therapeutic uses, potentially benefiting countless individuals who may be at risk of developing schizophrenia.
For further details, refer to the American Journal of Psychiatry, published in 2025 (DOI: 10.1176/appi.ajp.20240958).
