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Antibiotic exposure associated with increased risk for depression, anxiety

Recurrent exposure to antibiotics, particularly penicillin, was associated with increased risk for depression and anxiety, but not psychosis, according to study findings in Journal of Clinical Psychiatry.

“Although the potential role of gut microbiota in fatigue, melancholia, and the neuroses was described as early as the 1900s, research in the field was neglected until recent years,” Ido Lurie, MD, of Tel-Aviv University in Israel, and colleagues wrote. “Contemporary studies, both in animal models and in humans, indicate that the microbiota and changes in its composition (dysbiosis) affect the central nervous system, through neuronal, metabolic, and immunologic pathways and may also alter behavior and induce psychiatric-like conditions.”

Ido Lurie

To assess if exposure to specific antibiotic groups increased risk for depression, anxiety or psychosis, researchers conducted three nested case-control studies from 1995 to 2013 using a large population-based medical record database from the United Kingdom. The final study cohort included 202,974 individuals with depression and 803,961 age-matched controls, 14,570 with anxiety and 57,862 age-matched controls, and 2,690 with psychosis and 10,644 age-matched controls. Study participants were aged 15 to 65 years.

Treatment with a single antibiotic course was associated with increased risk for depression among all antibiotic groups, including penicillins (adjusted OR = 1.23; 95% CI, 1.18-1.29) and quinolones (1.25; 95% CI, 1.15-1.35).

Risk for depression increased with recurrent antibiotic exposures with an adjusted OR of 1.4 (95% CI, 1.35-1.46) for 2 to 5 courses of penicillin and 1.56 (95% CI, 1.46-1.65) for more than 5 courses of penicillin.

Researchers found a similar association for anxiety. Increased risk for anxiety was most prominent for a single course of penicillin (aOR = 1.44; 95% CI, 1.18-1.75) and more than 5 courses of penicillin (aOR = 1.44; 95% CI, 1.18-1.75).

Exposure to antibiotics was not associated with a change in risk for psychosis.

A single course of antifungals was associated with a mild increase in risk for depression and anxiety, however, there was no increased risk with repeated exposures.

“This is the first population-based study that demonstrated an association between exposure to specific antibiotic groups and risk for both depression and anxiety, but not psychosis. The risk increased with the number of antibiotic exposures and reached approximately 50% for more than 5 courses of penicillin,” Lurie and colleagues wrote. “Although we cannot rule out residual bias, those results are in line with recent animal models that show a central role for the gut–brain axis in neurologic pathways, behavior, and psychiatric pathology.” – by Amanda Oldt

Disclosure: Lurie reports no relevant financial disclosures. Please see the full study for a list of all researchers’ relevant financial disclosures.