Researchers at the Centre Psychothérapique de Nancy, France, has reported that retinal electrophysiological markers may act as indicators of therapeutic responses in depressed patients in real-life care conditions. SSRI (selective-serotonin reuptake inhibitor) and SNRI (serotonin-norepinephrine reuptake inhibitor) treatments for patients with major depressive disorder (MDD) may often require several weeks, or more, to assess clinical efficacy. However, ERG (electroretinogram) markers may provide a faster read-out for clinicians and patients alike treating MDD. Researchers believe this is the first study performed in real-life conditions to evaluate the effects of antidepressants on retinal function in major depressive disorder, potentially to provide significant earlier support for patients.
According to the French research team, the WHO (World Health Organization) ranked depression as the biggest contributor to global disability in 2017, with an estimated 322 million people worldwide. The public health consequences are major on a global scale, and the disorder is associated with a significant alteration in the quality of life and greater morbidity and mortality. One of the challenges to assess how monoamine neurotransmitters (such as dopamine, norepinephrine and serotonin) evaluate efficacy for patients, there is always a time-lag between treatment and results. Timely and efficient outcomes are required however, the delay to evaluate the efficacy of these types of treatment (SSRI and SNRIs) may take several weeks or more. In addition, therapeutic responses may not be certain for any individual patient and treatment modification may requires time, with the impact on quality-of-life issues and/or the development of secondary comorbidities.
In the current report, researchers stated that the structure and function of the retina in patients with MDD may consider ERG as a useful tool for the monitoring and diagnosis of psychiatric illnesses. Pattern ERG (PERG), flash ERG (fERG) and multifocal ERG (mfERG) were performed for this study using the standards of the International Society for Clinical Electrophysiology of Vision (ISCEV). The results of the research observed reduced b-wave amplitude of photopic fERG 3.0 in patients treated with SSRIs in comparison with patients treated with SNRIs, or Tricyclic Antidepressant (TCAD). Their study showed that SNRIs were associated both with a decrease in PERG P50 implicit time and an increase in fERG 3.0 b-wave amplitude. TCADs were also associated with an increase in fERG flicker 3.0 a- and b-wave amplitude. Commenting on their report, the researchers stated that “[o]ur results are interesting since they offer the opportunity to consider retinal electrophysiological markers as indicators of the therapeutic response in depressed patients in real-life care conditions. In the future, retinal electrophysiology may provide, in combination with other approaches and techniques, set of biomarkers to produce biosignatures in mental health. Investigations must therefore be prolonged and replicated to ascertain the precise effect of antidepressants on ERG. These results also support the use of ERG as a tool for monitoring and predicting therapeutic response in major depressive disorder”.