Lawrence Park

Anhedonia as a clinical correlate of suicidal thoughts in clinical ketamine trials

BACKGROUND Identifying clinical correlates associated with reduced suicidal ideation may highlight new avenues for the treatment of suicidal thoughts. Anhedonia occurs across psychiatric diagnoses and has been associated with specific neural circuits in response to rapid-acting treatments, such as ketamine. This analysis sought to evaluate whether reductions in suicidal ideation after ketamine administration were related to reduced levels of anhedonia, independent of depressive symptoms. METHODS This post-hoc analysis included treatment-resistant patients with either major depressive disorder (MDD) or bipolar disorder (BD) from several clinical trials of ketamine. Anhedonia was assessed using a subscale of the Beck Depression Inventory (BDI) and the Snaith-Hamilton Pleasure Scale (SHAPS). The outcome of interest was suicidal ideation, as measured by a subscale of the Scale for Suicide Ideation (SSI5), one day post-ketamine administration. RESULTS Anhedonia, as measured by the SHAPS, was associated with suicidal thoughts independent of depressive symptoms both before and after ketamine administration. One day post-ketamine administration, improvements on the SHAPS accounted for an additional 13% of the variance in suicidal thought reduction, beyond the influence of depressive symptoms. The BDI anhedonia subscale was not significantly associated with suicidal thoughts after adjusting for depressive symptoms. LIMITATIONS Data were limited to patients experiencing a major depressive episode and may not be generalizable to patients experiencing an active suicidal crisis. CONCLUSIONS Suicidal thoughts may be related to symptoms of anhedonia independent of other depressive symptoms. These results have implications for the potential mechanisms of action of ketamine on suicidal thoughts.

Parsing the heterogeneity of depression: An exploratory factor analysis across commonly used depression rating scales

BACKGROUND Due to the heterogeneity of depressive symptoms-which can include depressed mood, anhedonia, negative cognitive biases, and altered activity levels-researchers often use a combination of depression rating scales to assess symptoms. This study sought to identify unidimensional constructs measured across rating scales for depression and to evaluate these constructs across clinical trials of a rapid-acting antidepressant (ketamine). METHODS Exploratory factor analysis (EFA) was conducted on baseline ratings from the Beck Depression Inventory (BDI), the Hamilton Depression Rating Scale (HAM-D), the Montgomery-Asberg Depression Rating Scale (MADRS), and the Snaith-Hamilton Pleasure Rating Scale (SHAPS). Inpatients with major depressive disorder (n = 76) or bipolar depression (n = 43) were participating in clinical ketamine trials. The trajectories of the resulting unidimensional scores were evaluated in 41 subjects with bipolar depression who participated in clinical ketamine trials. RESULTS The best solution, which exhibited excellent fit to the data, comprised eight factors: Depressed Mood, Tension, Negative Cognition, Impaired Sleep, Suicidal Thoughts, Reduced Appetite, Anhedonia, and Amotivation. Various response patterns were observed across the clinical trial data, both in treatment effect (ketamine versus placebo) and in degree of placebo response, suggesting that use of these unidimensional constructs may reveal patterns not observed with traditional scoring of individual instruments. LIMITATIONS Limitations include: 1) small sample (and related inability to confirm measurement invariance); 2) absence of an independent sample for confirmation of factor structure; and 3) the treatment-resistant nature of the population, which may limit generalizability. CONCLUSIONS The empirical identification of unidimensional constructs creates more refined scores that may elucidate the connection between specific symptoms and underlying pathophysiology.

Motor-Activity Markers of Circadian Timekeeping Are Related to Ketamine’s Rapid Antidepressant Properties

BACKGROUND The rapid clinical antidepressant effects of the glutamatergic modulator ketamine may be due to its ability to restore synaptic plasticity and related effects on sleep-wake and circadian systems. Preclinical studies indicate that ketamine alters expression of circadian clock-associated molecules, and clinical studies of ketamine on plasticity-related biomarkers further suggest an association with sleep slow waves and sleep homeostasis. METHODS Wrist-activity monitors were used to examine the pharmacologic and rapid antidepressant effects of ketamine on markers of circadian timekeeping (amplitude and timing) in mood disorders. Circadian amplitude and timing of activity at baseline, postinfusion day 1 (D1), and day 3 (D3) were measured in 51 patients with major depressive disorder or bipolar disorder. RESULTS Compared with either placebo or baseline, a mood-independent decrease of the central circadian value (mesor) was present on D1 after ketamine treatment. Mood-associated circadian effects between rapid (D1) responders and nonresponders were found at baseline, D1, and D3. At baseline, a phase-advanced activity pattern and lower mesor distinguished subsequent responders from nonresponders. On D1, ketamine nonresponders had a lower mesor and a blunted 24-hour amplitude relative to baseline. On D3, patients with a persisting clinical response exhibited a higher amplitude and mesor compared with nonresponders. CONCLUSIONS The findings are the first to demonstrate an association between ketamines clinical antidepressant effects and circadian timekeeping. The results suggest that traitlike circadian activity patterns indicate rapid mood response to ketamine, and that mediators of continuing ketamine-induced mood changes include altered timing and amplitude of the circadian system.

Neurophysiological Changes Associated with Antidepressant Response to Ketamine Not Observed in a Negative Trial of Scopolamine in Major Depressive Disorder

Abstract Background This randomized, placebo-controlled, crossover trial examined the antidepressant efficacy of the muscarinic antagonist scopolamine in major depressive disorder subjects with more severe and refractory forms of major depressive disorder relative to previous reports. Methods Participants included 23 medication-free major depressive disorder subjects (12 F/11 M, 20–55 years) currently experiencing a major depressive episode. Subjects had scored ≥20 on the Montgomery-Asberg Depression Rating Scale. Following a single-blind, placebo lead-in, participants were randomized to receive 2 counterbalanced blocks of 3 i.v. infusions of scopolamine (4 μg/kg) and placebo in a double-blind manner. The primary and secondary outcomes were the Montgomery-Asberg Depression Rating Scale and the Hamilton Anxiety Rating Scale, respectively. Magnetoencephalography and plasma brain-derived neurotrophic factor concentrations were obtained prior to and after each treatment phase. Results As assessed by both the Montgomery-Asberg Depression Rating Scale and Hamilton Anxiety Rating Scale, scopolamine had no significant antidepressant or anxiolytic effects relative to placebo. No significant drug vs placebo effects were seen in magnetoencephalography gamma power or brain-derived neurotrophic factor plasma concentrations, and brain-derived neurotrophic factor changes did not correlate with change in Montgomery-Asberg Depression Rating Scale score in response to scopolamine. Conclusions These results do not support the efficacy of scopolamine for more severe or refractory forms of depression. No pre- to post-infusion changes in plasma brain-derived neurotrophic factor were detected, and magnetoencephalography gamma power changed only in the placebo lead-in, suggesting that these biomarker measures were not affected by scopolamine in this cohort. While difficult to interpret given the lack of antidepressant response, the findings suggest that the neurobiological effects of ketamine and scopolamine are at least partly distinct.

F173. Negative Trial of Scopolamine in Major Depressive Disorder Does Not Demonstrate Neurophysiological Changes Seen With the Antidepressant Response of Ketamine

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This conference abstract has been retracted at the request of author Maura Furey, with approval from the Society of Biological Psychiatry Executive Council, comprised of Mary L. Phillips, Scott L. Rauch, and Trey Sunderland. All other authors have been notified of this retraction. The retraction of this conference abstract has been requested due to multiple errors. The stated purpose of the study in the Background is not consistent with the actual purpose of the study as stated in the protocol and grant documents. Further, the purpose improperly references comparison with ketamine, when ketamine was not tested in this study. In the Results, the outcome of a secondary analysis is reported that is not specified and is contradictory to the primary finding of no significant effect. The first statement in the Conclusions is not supported by the data. In addition, the second statement in the Conclusions is inaccurate because mechanism of action was not assessed in this study, nor was ketamine studied or compared with scopolamine. Lastly, all authors did not review and approve this abstract prior to its submission.

Active suicidal ideation during clinical antidepressant trials

Suicidal patients are often excluded from clinical trials of psychiatric medications and from investigations using neurobiological techniques. To evaluate the presence, impact, and stability of active suicidal ideation (SI) across a range of antidepressant trials, we reviewed 14 clinical trials conducted in patients with either major depressive disorder (MDD) or bipolar disorder (BD) (N = 269). Active SI at any time point in the clinical trial was identified and linked to participation in other research procedures. Stability of active SI across subsequent days was evaluated using intraclass correlation coefficients (ICCs) and compared to other depressive symptoms. Across 14 clinical trials, 63 participants (23%) reported active SI at some point during study participation. Of these participants, 33 completed a neuroimaging procedure and 16 completed polysomnography within a week of active SI. When active SI was subsequently assessed, only 39% of patients continued to report active SI after three days of assessment, despite receiving no additional treatment. ICCs were not significant for either SI or pessimism; other depressive symptoms showed stability over time. The results suggest that research can be conducted in depressed patients with active SI if such research coincides with careful observation. Active SI and pessimism may be particularly vulnerable to fluctuation.

The antidepressant efficacy of subanesthetic-dose ketamine does not correlate with baseline subcortical volumes in a replication sample with major depressive disorder

Background: This study sought to reproduce, in a larger sample, previous findings of a correlation between smaller raw 3-Tesla (3T) hippocampal volumes and improved antidepressant efficacy of ketamine in individuals with major depressive disorder (MDD). A secondary analysis stratified subjects according to functional BDNF rs6265 (val66met) genotype. Methods: Unmedicated subjects with treatment-resistant MDD (n=55) underwent baseline structural 3T MRI. Data processing was conducted with FSL/FIRST and Freesurfer software. The amygdala, hippocampus, and thalamus were selected a priori for analysis. All subjects received a single 0.5mg/kg × 40-minute ketamine infusion. Pearson correlations were performed with subcortical volumes and percent change in MADRS score (from baseline to 230 minutes, 1 day, and 1 week post-infusion). Results: Raw and corrected subcortical volumes did not correlate with antidepressant response at any timepoint. In val/val subjects (n=23), corrected left and right thalamic volume positively correlated with antidepressant response to ketamine at 230 minutes post-infusion but did not reach statistical significance. In met carriers (n=14), corrected left and right thalamic volume negatively correlated with antidepressant response to ketamine. Conclusion: Baseline subcortical volumes implicated in MDD did not correlate with ketamine’s antidepressant efficacy. Baseline thalamic volume and BDNF genotype may be a combinatorial rapid antidepressant response biomarker.