The non-competitive N-methyl-d-aspartate glutamate receptor antagonist ketamine has been shown to have rapid antidepressant effects in treatment-resistant depression (TRD). However, only a few studies have investigated which clinical characteristics predict a response to ketamine.

To assess sociodemographic variables and clinical markers that predict response to ketamine in unipolar TRD patients.

Searches of Pubmed, NCBI and Google Scholar were conducted for clinical trials and systematic reviews, through October 2016, using the keywords:

ketamine, N-methyl-d-aspartate receptor antagonist, rapid-acting antidepressant, depression, treatment-resistant depression, clinical predictors.

Findings support the following clinical predictors:

– sociodemographic variables: positive family history of alcohol abuse disorder in first-degree relative (increased antidepressant response and fewer depressive symptoms for up to 4weeks post-infusions), higher BMI (improvement in depression severity at 230minutes and one day post-infusion), negative history of suicide attempt (greater improvement at day 7);

– infusion-associated events: greater dissociation during infusion (better antidepressant response at 230minutes and one week post-infusion); rapid response to first infusion (sustained response to subsequent infusions in one-third responders for up to 83days);

– symptomatology: anxious depression (fewer depression symptoms at day one up to 25 associated with longer time to relapse); neurocognitive performance (lower attention) predicts change in severity of depressive symptoms over six infusions.

Findings suggest that specific clinical characteristics are predictors of ketamine response in TRD. Future studies confirming reliable predictors will assist clinicians to implement efficacious and individualized treatment for TRD patients.