Electroretinographic assessment in major depressed patients receiving duloxetine: might differences between responders and non-responders indicate a differential biological background?

INTRODUCTION: Despite intense research efforts, still too little is known about the biological determinants of depression, thus soliciting diverse study approaches. Among others, the electroretinography (ERG) has been proposed even as a putative proxy (retinal) measurement of central dopaminergic activity for Major Depressive Disorder (MDD) both in drug-naïve patients and subjects receiving antidepressant treatments. Nonetheless, current evidences are merely preliminary, essentially considering just older classes of antidepressants, thus requiring confirmation studies even with newer agents as duloxetine.
METHOD: Twenty MDD subjects and 20 matched controls received duloxetine 60 mg/day for 12 weeks, being monitored both by standard ERG recording and by administration of the Hamilton scales for Depression and Anxiety and the Young Mania Rating Scale at baseline and week 12 (end of the study).
RESULTS: ERG mean rod b-wave amplitude significantly reduced from baseline to week 12 in those depressed subjects achieving final response (p=.024), decreasing from the highest rank values to the ones, substantially unmodified, seen among non-responders and controls. LIMITATIONS: Small sample size and lack of multiple assessments.
CONCLUSIONS: At least some MDD patients responding to duloxetine might exhibit a peculiar ERG pattern, hypothetically indicating a specific biological background. If confirmed by larger-sampled studies, these results might shed further light in the understanding of the biological determinants of different subtypes of depression, ideally showing alternative patterns of response upon different treatment interventions.