Recent benzodiazepine use in depressed patients: a confound of psychoimmunologic studies?

Several studies have indicated that benzodiazepines influence immunity in both animals and humans. As these medications are commonly utilized by and for psychiatric patients, investigation of psycho-immunologic relationships in human psychiatric disorders may be confounded by use of these medications.

We undertook an investigation for possible effects of recent benzodiazepine use on depression-immune relationships by comparing 43 patients with current major depressive disorder (MDD) who used benzodiazepines in the week prior to study to 27 patients with current MDD but no use of benzodiazepines in the past month. Both functional and ennumerative measures were investigated.

We found no differences in absolute numbers of lymphocytes or the lymphocyte and NK functional measures. We did find differences between these two groups in the percentage of lymphocytes and of NK cells. Upon further analysis, controlling for symptom severity, these differences were shown to not be independently predicted by benzodiazepine use.

Immune measures in subjects with current MDD and recent benzodiazepine use did not differ from those without such recent use. Therefore, such recent use is unlikely to confound PNI results.