Predictors of response to intranasal ketamine in patients hospitalized for treatment-resistant depression

Background Ketamine is recognized as an effective treatment for major depressive disorder but there remains a need to identify predictors of response to ketamine therapy. Methods This naturalistic study was a retrospective analysis of data from 48 patients with treatment-resistant depression who received up to four doses of intranasal ketamine in an acute psychiatric hospital setting. Baseline demographic and clinical variables were examined as potential predictors of response along with treatment-emergent dissociation and blood pressure changes. Response was defined as a depression score decrease of 50% or more from baseline measured with the Hamilton Depression Rating Scale or the Montgomery–Åsberg Depression Rating Scale. Results The response rate was significantly lower in patients diagnosed with a personality disorder, the most common of which was borderline personality disorder. In contrast, baseline scores on patient-reported questionnaires assessing maladaptive personality traits were not associated with lower response rates. Adverse childhood experiences and dissociation during treatment were associated with higher response rates. Conclusions Patients with significant childhood trauma appeared to benefit more from ketamine treatment, consistent with previous research. More research to determine if personality disorders influence ketamine response is needed and should distinguish clinical diagnoses from those derived solely from patient-reported questionnaires. Treatment-emergent dissociation could be a predictor of response to intranasal ketamine but requires further study.