Clinical and biological predictors of ketamine response in treatment-resistant major depression: Review

Objective. - The aim of this review was to determine the clinical and biological predictors of the ketamine response. Methods. - A systematic research on PubMed and PsycINFO database was performed without limits on year of publication. Results. - The main predictive factors of ketamine response, which were found in different studies, were (i) a family history of alcohol dependence, (ii) unipolar depressive disorder, and (iii) neurocognitive impairments, especially a slower processing speed. Many other predictive factors were identified, but not replicated, such as personal history of alcohol dependence, no antecedent of suicide attempt, anxiety symptoms. Some biological factors were also found such as markers of neural plasticity (slow wave activity, brain-derived neurotrophic factor VaI66Met polymorphism, expression of Shank 3 protein), other neurologic factors (anterior cingulate activity, concentration of glutamine/glutamate), inflammatory factors (IL-6 concentration) or metabolic factors (concentration of B12 vitamin, D- and L-serine, alterations in the mitochondria' beta-oxidation of fatty acids). This review had several limits: (i) patients had exclusively resistant major depressive episodes which represent a sub-type of depression and not all depression, (ii) response criteria were more frequently assessed than remission criteria, it was therefore difficult to conclude that these predictors were similar, and finally (iii) many studies used a very small number of patients. Conclusions. - In conclusion, this review found that some predictors of ketamine response, like basal activity of anterior cingulate or vitamin B12 concentration, were identical to other therapeutics used in major depressive episode. These factors could be more specific to the major depressive episode and not to the ketamine response. Others, like family history of alcohol dependence, body mass index, or D and L-serine were different from the other therapeutics. Neurocognitive impairments like slower speed processing or alterations in attention tests were also predictive to a good response. These predictive factors could be more specific to ketamine. With these different predictor factors (clinical and biological), it could be interesting to develop clinical strategies to personalize ketamine's administration. (C) 2016 L'Encephale, Paris.