Volumetric changes in subcortical structures following repeated ketamine treatment in patients with major depressive disorder: a longitudinal analysis.

Abnormal subcortical structures have been associated with major depressive disorder (MDD) and could be reversed by antidepressant treatment. To date no study has examined the relationship between subcortical volumes and repeated ketamine treatment. The current study investigated volume changes in specific subcortical structures and hippocampal subfields after six ketamine infusions. Forty-four patients with MDD received six subanesthetic dose infusions of ketamine. Depressive symptoms were assessed and magnetic resonance imaging scans were performed before and after six ketamine infusions. FreeSurfer software was used to process the T1 images and analyze the volumes of the subcortical regions and hippocampal subfields. After six ketamine infusions, increases were observed in the volumes of the left amygdala; the right hippocampus; the cornu ammonis 4 body, granule cell and molecular layer of the dentate gyrus body in the left hippocampus; and the cornu ammonis 4 head and molecular layer head in the right hippocampus. Positive correlations were found between symptom improvement and the pretreatment volumes of the right thalamus (r = 0.501; P = 0.001) and left subiculum head of the hippocampus (r = 0.471; P = 0.002), and changes in the volumes of the left amygdala (r = -0.452; P = 0.003) and the left cornu ammonis 4 body (r = -0.537; P < 0.001). Our findings provided evidence for critical roles of the amygdala and specific hippocampal subfields in the antidepressant effect of repeated ketamine treatment. Relatively larger volumes in right thalamus and left subiculum head in the hippocampus can predict a superior clinical outcome of ketamine treatment in MDD patients.

A preliminary study of adjunctive ketamine for treatment-resistant bipolar depression.

OBJECTIVES: Ketamine has shown rapid antidepressant effects in depressed patients. However, the antidepressant and antisuicidal effects of repeated ketamine infusions in patients with treatment-resistant bipolar depression (TRBD) are not known. METHODS: TRBD patients received six intravenous infusions of 0.5 mg/kg ketamine over 40 min on a Monday-Wednesday-Friday schedule during a 12-day period followed by a 2-week follow-up period. Depressive symptoms were measured by the Montgomery-Asberg Depression Rating Scale (MADRS) at baseline and at each follow-up visit. RESULTS: Nineteen patients with TRBD were enrolled in the study, and 16 patients (84.2%) received all six ketamine infusions. After the first infusion, the rates of response and remission were 21.1% (95% CI: 0.9 to 21.2) and 15.8% (95% CI: 0 to 33.9), respectively, and after the sixth infusion, the rates of response and remission were 73.7% (95% CI: 51.9 to 95.5) and 63.2% (95% CI: 39.3 to 87.0), respectively. The average times for nineteen patients who responded and remitted were 9.1 and 12.5 days, respectively. There were large decreases in the scores on the MADRS and the Scale for Suicidal Ideation-part 1 within 4 h after the first infusion, and the decreases were maintained across subsequent infusions. There were no significant increases in dissociative and psychotomimetic symptoms as measured by the Clinician-Administered Dissociative States Scale (CADSS) and the Brief Psychiatric Rating Scale (BPRS)-4 items, respectively. CONCLUSION: These pilot findings suggest the feasibility of repeated ketamine infusions at subanaesthetic doses for patients with TRBD. Future controlled studies are needed to confirm and expand these findings.

Investigation of medical effect of multiple ketamine infusions on patients with major depressive disorder.

OBJECTIVE: Single-dose intravenous ketamine has rapid but time-limited antidepressant effects. We aimed to examine the sustained effects of six consecutive ketamine infusions in Chinese patients with major depressive disorder. METHODS: Seventy-seven patients with major depressive disorder were eligible to receive augmentation with six ketamine infusions (0.5 mg/kg over 40 min) administered over the course of 12 days (Monday-Wednesday-Friday). The coprimary outcome measures were the rates of response and remission as measured on the 10-item Montgomery-Asberg Depression Rating Scale. Psychotomimetic and dissociative symptoms were measured with the Brief Psychiatric Rating Scale-positive symptoms and the Clinician Administered Dissociative States Scale, respectively. RESULTS: After the first ketamine infusion, only 10 (13.0%) and 6 (7.8%) patients responded and remitted, respectively; after six ketamine infusions, 52 (67.5%) patients responded and 37 (48.1%) remitted. There was a significant mean decrease in Montgomery-Asberg Depression Rating Scale score at four hours after the first ketamine infusion (7.0±7.5, p<0.001), and this decrease was maintained for the duration of the infusion period. The response to ketamine treatment was positively associated with no history of psychiatric hospitalization (odds ratio=3.56, p=0.009). Suicidal ideation rapidly decreased across the entire study sample, even among the nonresponder group. No significant differences were found regarding Brief Psychiatric Rating Scale and Clinician Administered Dissociative States Scale scores from the first infusion at baseline to four hours post-infusion. CONCLUSION: Six ketamine infusions increased rates of response and remission when compared to a single-dose ketamine infusion in patients with major depressive disorder. Future controlled studies are warranted to confirm and expand these findings.

Neurocognitive performance and repeated-dose intravenous ketamine in major depressive disorder.

OBJECTIVE: Ketamine has demonstrated a rapid antidepressant and antisuicidal effect in patients with major depressive disorder (MDD), but the neurocognitive effects of ketamine are relatively unknown. This study aims to examine the neurocognitive effects of six ketamine infusions and the association of baseline neurocognitive function and the change in severity of depressive symptoms after the last infusions. METHODS: Sixty-four patients with MDD completed six intravenous infusions of ketamine (0.5 mg/kg over 40 min) administered over a 12-day period (Monday-Wednesday-Friday), and were followed by a 2-week observational period. Four domains of neurocognitive function (including speed of processing, working memory, visual learning and verbal learning) were assessed using the MATRICS Consensus Cognitive Battery (MCCB) at 0, 13 and 26 days. RESULTS: In linear mixed model, significant improvements were found in terms of speed of processing (F = 20.7, p < 0.001) and verbal learning (F = 11.1, p < 0.001). The Sobel test showed the improvement of speed of processing (Sobel test = 2.8, p < 0.001) and verbal learning (Sobel test = 3.6, p < 0.001) were significantly mediated by change in depressive symptoms. Other two neurocognitive domains showed no significant changes over time. Correlation analysis showed no significant association of change in depressive symptoms with neurocognitive function at baseline. CONCLUSION: Our findings suggest that six ketamine infusions were associated with the improvement of speed of processing and verbal learning, which were partly accounted for by improvement in the severity of depression symptoms over time.

Rapid and longer-term antidepressant effects of repeated-dose intravenous ketamine for patients with unipolar and bipolar depression.

OBJECTIVE: Single-dose intravenous (IV) injection of ketamine has shown rapid but transient antidepressant effects. The strategy of repeated-dose ketamine infusions to maintain antidepressant effects has received little systematic study. This study was conducted to examine the efficacy and tolerability of six ketamine infusions in Chinese patients with unipolar and bipolar depression. METHODS: Ninety seven patients with unipolar (n = 77) and bipolar (n = 20) depression received repeated ketamine infusions (0.5 mg/kg over 40 min) with continuous vital sign monitoring. Depressive symptoms were measured by the Montgomery-Asberg Depression Rating Scale (MADRS). Suicidal ideation was assessed using the Scale for Suicidal Ideations (SSI)-part 1. Anxiety symptoms were evaluated with the 14-item Hamilton Anxiety Scale (HAMA). Adverse psychopathological and dissociative effects were assessed using the Brief Psychiatric Rating Scale (BPRS)-positive symptoms and Clinician Administered Dissociative States Scale (CADSS), respectively. Patients were assessed at baseline, 4 and 24 h, and 3, 4, 5, 6, 8, 9, 10, 11, 12, 13 and 26 days. RESULTS: After six ketamine infusions, the response and remission rates were 68.0% and 50.5%, respectively. There were significant decreases in MADRS, SSI-part 1, and HAMA scores within four hours following the first ketamine infusion, and the decreases were sustained over the subsequent infusion period. The nonresponder subgroup manifested rapid significant improvement in suicidal ideations throughout the course of treatment. After the six ketamine infusions, the response was positively associated with the response at 24 h after the first infusion (OR = 8.94), personal income ≥4000 yuan/month (OR = 3.04), and no history of psychiatric hospitalization (OR = 3.41). Only CADSS scores had a mild but marginally significant increase after the first infusion but with a significant BPRS score decrease. CONCLUSION: Six ketamine infusions were safe and effective in patients with unipolar and bipolar depression. The rapid and robust antidepressant and antisuicidal effects of ketamine infusion within four hours were sustained following the subsequent infusions.