Associations Between Chlamydia trachomatis Infection and Depression

This study investigated the associations between Chlamydia trachomatis and depression in subjects with and without urogenital symptoms, in males and females, and across different severities of depression.

We reviewed electronic medical records from the University of Louisville Campus Health Services. Data on mood, C. trachomatis and Neisseria gonorrhoeae infection statuses, symptoms, age, sex, and the use of alcohol, cigarettes, and illicit drugs were analyzed.

Across the entire study cohort (n = 839), C. trachomatis infection was associated with an increased likelihood of reporting depression (adjusted odds ratio [aOR], 1.79; 95% confidence interval [CI], 1.19-2.69). The odds of reporting depression remained elevated when the analysis was restricted to infected patients without urogenital symptoms (aOR, 1.75; 95% CI, 1.07-2.80). In a sex-stratified analysis, C. trachomatis infection was associated with a statistically significant increased odds of reporting depression in females (aOR, 2.09; 95% CI, 1.25-3.45) but not in males. When subjects were categorized according to an ordered scale of depression, C. trachomatis infection was associated with increased odds of falling into a more severe category (OR, 1.83; 95% CI, 1.251-2.694). Finally, using a within-subject design, patients were more likely to report depression when infected at the time of the appointment compared with when the same patients were uninfected (OR, 3.17; 95% CI, 1.22-9.69).

Our results are consistent with C. trachomatis contributing to the spectrum of depression independent of urogenital symptoms. We propose that these depression findings may result from an immune system response that lowers serotonin availability.