The use of functional near-infrared spectroscopy (fNIRS) as a potential marker of the efficacy and safety of electroconvulsive therapy

Purpose
Neuroimaging and biological predictors of response to electroconvulsive therapy (ECT) are still being sought, so as to enable a full understanding of its therapeutic effects. The present study aims to determine the role of functional near-infrared spectroscopy (fNIRS) as a potential predictor of response to treatment with and efficacy of ECT.

Views
Each of the currently used neuroimaging methods has its limitations; however, the advantages of fNIRS provide a starting point for the widespread use of this method in the assessment of ECT. Studies using fNIRS for measurement have shown that prior to undergoing ECT depressed patients have a bilaterally lower frontal oxyhaemoglobin response to cognitive tasks compared to healthy subjects. After ECT, there is a change in oxyhaemoglobin (oxy-Hb) values compared to pre-treatment ones. However, the results regarding changes in oxy-Hb values obtained by different groups of investigators were not consistent.

Conclusions
Higher oxy-Hb values are achieved in healthy subjects than in patients. Apart from that, oxy-Hb values in patients are altered after ECT. For this reason the use of fNIRS can be an objective assessment of its therapeutic effect on patients. However, for fNIRS to become a biomarker for ECT treatment, studies need to be conducted on a larger patient population, considering the time since the last ECT and various disease entities.