OPEN Foundation

Day: 8 November 2014

Improvement in suicidal ideation after ketamine infusion: Relationship to reductions in depression and anxiety



Suicide is a psychiatric emergency. Currently, there are no approved pharmacologic treatments for suicidal ideation. Ketamine is an N-methyl-D-aspartate (NMDA) receptor antagonist that rapidly reduces suicidal ideation as well as depression and anxiety, but the dynamic between these symptoms is not known. The aim of this analysis was to evaluate whether ketamine has an impact on suicidal thoughts, independent of depressive and anxiety symptoms.


133 patients with treatment-resistant depression (major depressive disorder or bipolar I/II disorder) received a single subanesthetic infusion of ketamine (0.5 mg/kg over 40 min). Post-hoc correlations and linear mixed models evaluated the relationship between suicidal ideation and depression and anxiety symptoms using the Hamilton Depression Rating Scale (HAMD), Scale for Suicidal Ideation (SSI), Beck Depression Inventory (BDI), and Hamilton Anxiety Rating Scale (HAMA) focusing on 230 min post-infusion.


At 230 min post-infusion, correlations between changes in suicidal ideation and depression ranged from 0.23 to 0.44 (p < .05), accounting for up to 19% in the variance of ideation change. Correlations with anxiety ranged from 0.23 to 0.40 (p < .05), accounting for similar levels of variance. Ketamine infusion was associated with significant reductions in suicidal ideation compared to placebo, when controlling for the effects of ketamine on depression (F1,587 = 10.31, p = .001) and anxiety (F1,567 = 8.54, p = .004).


Improvements in suicidal ideation after ketamine infusion are related to, but not completely driven by, improvements in depression and anxiety. Investigation of the specific effects of ketamine on suicidal thoughts is warranted.

Ballard, E. D., Ionescu, D. F., Voort, J. L. V., Niciu, M. J., Richards, E. M., Luckenbaugh, D. A., … & Zarate, C. A. (2014). Improvement in suicidal ideation after ketamine infusion: relationship to reductions in depression and anxiety. Journal of psychiatric research, 58, 161-166.

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Effects of ecstasy on cooperative behaviour and perception of trustworthiness: A naturalistic study


Background: Acute recreational use of 3,4-methylenedioxymethamphetamine (MDMA; ‘ecstasy’) can promote pro-social effects which may alter interpersonal perceptions.

Aims: To explore such effects, this study investigated whether acute recreational use of ecstasy was associated with changes in individual perception of trustworthiness of people’s faces and co-operative behaviours.

Method: An independent group, repeated measures design was used in which 17 ecstasy users were tested on the night of drug use (day 0) and again three days later (day 3); 22 controls were tested on parallel days. On each day, participants rated the trustworthiness of 66 faces, carried out three co-operative behaviour tasks (public good; dictator; ultimatum game) and completed mood self-ratings.

Results: Acute ecstasy use was associated with increased face trustworthiness ratings and increased cooperative behaviour on the dictator and ultimatum games; on day 3 there were no group differences on any task. Self-ratings showed the standard acute ecstasy effects (euphoria, energy, jaw clenching) with negative effects (less empathy, compassion, more distrust, hostility) emerging on day 3.

Conclusions: Our findings of increased perceived trustworthiness and co-operative behaviours following use of ecstasy suggest that a single dose of the drug enhances aspects of empathy. This may in turn contribute to its popularity as a recreational drug and potentially to its enhancement of the therapeutic alliance in psychotherapy.

Stewart, L. H., Ferguson, B., Morgan, C. J. A., Swaboda, N., Jones, L., Fenton, R., … & Curran, H. V. (2014). Effects of ecstasy on cooperative behaviour and perception of trustworthiness: A naturalistic study. Journal of Psychopharmacology, 28(11), 1001-1008.

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M1 and M2 Muscarinic Receptor Subtypes Regulate Antidepressant-Like Effects of the Rapidly Acting Antidepressant Scopolamine


Scopolamine produces rapid and significant symptom improvement in patients with depression, and most notably in patients who do not respond to current antidepressant treatments. Scopolamine is a nonselective muscarinic acetylcholine receptor antagonist, and it is not known which one or more of the five receptor subtypes in the muscarinic family are mediating these therapeutic effects. We used the mouse forced-swim test, an antidepressant detecting assay, in wild-type and transgenic mice in which each muscarinic receptor subtype had been genetically deleted to define the relevant receptor subtypes. Only the M1 and M2 knockout (KO) mice had a blunted response to scopolamine in the forced-swim assay. In contrast, the effects of the tricyclic antidepressant imipramine were not significantly altered by gene deletion of any of the five muscarinic receptors. The muscarinic antagonists biperiden, pirenzepine, and VU0255035 (N-[fusion_builder_container hundred_percent=”yes” overflow=”visible”][fusion_builder_row][fusion_builder_column type=”1_1″ background_position=”left top” background_color=”” border_size=”” border_color=”” border_style=”solid” spacing=”yes” background_image=”” background_repeat=”no-repeat” padding=”” margin_top=”0px” margin_bottom=”0px” class=”” id=”” animation_type=”” animation_speed=”0.3″ animation_direction=”left” hide_on_mobile=”no” center_content=”no” min_height=”none”][3-oxo-3-[4-(4-pyridinyl)-1-piper azinyl]propyl]-2,1,3-benzothiadiazole-4-sulfonamide) with selectivity for M1 over M2 receptors also demonstrated activity in the forced-swim test, which was attenuated in M1 but not M2 receptor KO mice. An antagonist with selectivity of M2 over M1 receptors (SCH226206 [(2-amino-3-methyl-phenyl)-[4-[4-[[4-(3 chlorophenyl)sulfonylphenyl]methyl]-1-piperidyl]-1-piperidyl]methanone]) was also active in the forced-swim assay, and the effects were deleted in M2−/− mice. Brain exposure and locomotor activity in the KO mice demonstrated that these behavioral effects of scopolamine are pharmacodynamic in nature. These data establish muscarinic M1 and M2 receptors as sufficient to generate behavioral effects consistent with an antidepressant phenotype and therefore as potential targets in the antidepressant effects of scopolamine.

Witkin, J. M., Overshiner, C., Li, X., Catlow, J. T., Wishart, G. N., Schober, D. A., … & Felder, C. C. (2014). M1 and M2 Muscarinic Receptor Subtypes Regulate Antidepressant-Like Effects of the Rapidly Acting Antidepressant Scopolamine. Journal of Pharmacology and Experimental Therapeutics, 351(2), 448-456.
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