Ketamine for Unipolar and Bipolar Depression
Early clinical trials demonstrate that using intravenous and intranasal ketamine for unipolar and bipolar depression offer the possibility for safe and rapid relief of symptoms with high response rates (up to 88%) and pronounced antisuicidal effects.
Administration of Ketamine for Unipolar and Bipolar Depression
The article below is part of Frshmind’s “Psychedelic Science Snapshot Series” where Frshminds reviews the latest in psychedelic research.
Original authors: Christoph Kraus, Ulrich Rabl, Thomas Vanicek, Laura Carlberg, Ana Popovic, Marie Spies, Lucie Bartova, Gregor Gryglewski, Konstantinos Papageorgiou, Rupert Lanzenberger, Matthäus Willeit, Dietmar Winkler, Janusz K. Rybakowski & Siegfried Kasper
Summarized by: Emily Fewster
Introduction to the Use of Ketamine for Treatment of Unipolar and Bipolar Depression
Treatment-resistant depression (TRD) is defined as non-response to more than two antidepressant trials, occurs in about 10–30% of all major depressive disorder patients (Schosser et al. 2012; Balestri et al. 2016), and is associated with higher risk of suicide, high relapse rates and large socioeconomic burden for patients as well as for health care providers (Schosser et al. 2012; Mrazek et al. 2014; Kautzky et al. 2015). 21 years ago, the antidepressant effects of ketamine were tested for the first time in depressed patients (Berman et al. 2000) due to issues of efficacy with conventional antidepressants. Since ketamine has been used as an anaesthetic for over 40 years at dosages two to five times higher than those applied in antidepressant treatment regimes, toxicity, possible side effects and pharmacokinetic characteristics are well known.
However, at the time of this paper’s publication, usage in clinical psychiatry had not yet been approved by regulatory agencies due to unanswered questions in regard to various factors such as application modality, interactions with other medications, safety in long-term administration, and side effects in a vulnerable population such as TRD-patients. As a result, a growing number of ‘ketamine-clinics’ would provide off-label antidepressant ketamine treatment and promise illusory success, discarding scientific and available clinical standards (Schak et al. 2016). Thus, the authors of this study aimed to assess the effects of ketamine in a clinical context for the treatment of unipolar or bipolar depression and to provide guidance for clinical treatment, including information on potential adverse effects.
Authors selected 19 clinical trials, 12 concerning unipolar MDD (Berman et al. 2000; Zarate et al. 2006; Price et al. 2009; aan het Rot et al. 2010; Mathew et al. 2010; Larkin & Beautrais 2011; Thakurta et al. 2012; Murrough et al. 2013; Sos et al. 2013; Ghasemi et al. 2014; Lapidus et al. 2014; Singh et al. 2015) and 7 on bipolar depression (Diazgranados et al. 2010; Luckenbaugh et al. 2012; Zarate et al. 2012; Rybakowski et al. 2012; Permoda-Osip et al. 2013, 2014, 2015). Each study had been published in peer-reviewed journals, ascertained clinical symptoms of unipolar or bipolar depression using DSM-IV or a similar set of criteria, and only used standardized and reliable outcome measures.
Amount these outcome measures included measures for depression; the Hamilton Depression Rating Scale (HAM-D), the Montgomery-Asberg Depression Rating Scale (MADRS), the Beck Depression Inventory (BDI), and the Quick Inventory of Depressive symptomatology (QIDS). The primary outcome parameter in every study was change of depression rating scores (HAM-D, MADRS, BDI or QIDS), with assessments performed in most trials at 24-h post-treatment. Seven trials indicated response and remission rates, with response defined as 50% reduction of baseline depression scores in all studies. Secondary measures in some trials included visual analogue scales for intoxication, the Young Mania Rating Scale, the Clinician-administered Dissociative States Scale (CADSS), the systematic assessment for treatment effects self-report inventory, the scale for suicide ideation (SSI), and the clinical global impression (CGI) scales.
Ketamine in unipolar depression
Ketamine Study Results
Across the 12 clinical trials a total of 226 major depressive (MDD) patients were treated with ketamine using various methods of administration, dose amount, and dose frequency. All studies identified a rapid and robust antidepressant effect, with ketamine always statistically superior to placebo and average response rates of 59% (ranging between 37% and 88%) after 24h. This equalled an average reduction of 10.91 points on the HAM-D, 15.7 points on BDI and 20.8 points on MADRS. Three consecutive administrations of ketamine also proved to be superior to three ECT sessions as measured 48h, 72h and 1 week post-ketamine and ECT treatment, with the largest effects observed 24-h post-treatment and lasting for several days (Ghasemi et al. 2014). The study by Murrough et al. (2013) indicated that the response to the first infusion is predictive to the subsequent outcome in the sense that responders remain responsive to ketamine and vice versa. Regarding relapse rates, the first two published trials reported 92% of all patients receiving ketamine relapsed within 2 weeks post-treatment. In the study by aan het Rot et al., eight out of nine patients who received repeated infusions relapsed within an average of 30 days after the first infusion or 19 days after the sixth infusion (aan het Rot et al. 2010). Mathew et al. (2010) reported a relapse rate of 62% (eight out of 13 patients) in a time period of 30 days, and Murrough et al. (2013) also report relapse rates of about 60% after 30 days.
Ketamine in bipolar depression
Diazgranados et al. (2010) conducted the first study reporting the beneficial effect of i.v. ketamine as an adjunct to mood stabilizers (lithium or valproate) for bipolar depression, with clinical improvement lasting for 14 days in 71% of patients. This was replicated by Zarate et al.
(2012), who demonstrated improvement in 12 of 15 bipolar depressed patients (79%), again maintained for 14 days. Another study by the Department of Adult Psychiatry at Poznan University of Medical Sciences investigated response criteria after a single infusion in 53 bipolar patients (Rybakowski et al. 2013). All patients received at least one mood-stabilising drug and had previously been treated with antidepressant drugs without much improvement. HAM-D scores after 24 h were an average of 15.6, to 14.2 on the third day, to 12.5 on the seventh day and finally to 11.8 2 weeks following ketamine infusion. On the seventh day after ketamine infusion, 27 subjects met the criterion for response and interestingly, response after ketamine infusion occurred significantly more frequently in male (77%) than in female (43%) bipolar subjects. This is in line with a recent meta-analysis (Coyle & Laws 2015) in which male sex was a predictor of antidepressant response at seven days, though exact reasons are unclear. These results correspond to other trials indicating a substantial antidepressant effect of a single ketamine infusion in bipolar depressed patients receiving lithium or valproate, though the percentage of patients with improvement after 7 days in this study was somewhat lower than in the two previous trials in bipolar depression (Diazgranados et al. 2010; Zarate et al. 2012) (52% versus 71%
and 79%). The effect sizes were larger in MDD patients as compared with patients suffering from bipolar disorder, which hints towards the different neuropathologies of bipolar disorder.
Safety and tolerability of Ketamine Treatment for Unipolar and Bipolar Depression
Five studies measured psychotic (positive) symptoms during and shortly after ketamine infusion using the Brief Psychiatric Rating Scale (BPRS) (Zarate et al. 2006; aan het Rot et al. 2010; Mathew et al. 2010; Lapidus et al. 2014; Singh et al. 2015). Zarate et al. (2006) reported entirely reversible positive symptoms only detectable at 40-min post-infusion which was confirmed by aan het Rot et al., who showed a change in and subsequent return to baseline BPRS scores by 2-h post-infusion (aan het Rot et al. 2010). Other studies made similar observations (Sos et al. 2013; Singh et al. 2015) and interestingly, one study found stronger reductions in HAM-D scores upon more psychotic symptoms (Sos et al. 2013), though others failed to detect this correlation (aan het Rot et al. 2010; Mathew et al. 2010; Lapidus et al. 2014). The occurence of adverse events was very minimal, with only one study reporting hypotension/bradycardia (decreased heart rate) and a suicide attempt (Murrough et al. 2013), with the hypotension/bradycardia linked to a stress response during the puncturing of the vein. Another study reported an adverse event where one patient fell and sustained an injury to the wrist, though this was classified as not related to the treatment intervention (Singh et al. 2015). Other than these events, no other study reported serious events.
Regarding general adverse effects, Murrough et al. (2013) found that of the 47 patients receiving ketamine, 17% had dissociative symptoms such as feeling outside of their bodies or reported altered perception of time, thought these states were transient and no severe psychotic symptoms occurred in any patient. Zarate et al. (2006) also found transient perceptual disturbances, confusion, elevations in blood pressure, euphoria, dizziness and increased libido. Moreover, adverse events were recorded by aan het Rot et al. (2010) with a self-report inventory (SAFTEE) and it was found that abnormal sensations and weakness/fatigue increased in prevalence during the second week of infusions, yet symptoms were no greater than ‘mildly bothersome’. Intranasal ketamine was associated with small increases in systolic blood pressure to baseline (Lapidus et al. 2014) and generally less side effects.
In comparison with other treatments for TRD such as ECT, ketamine is less invasive. Even intravenous ketamine does not need supervision by an anaesthetist and can be performed in. a controlled outpatient setting in stable patients (aan het Rot et al. 2010; Murrough et al. 2013). Nevertheless, cardiovascular monitoring during infusion is recommended, and careful observation of potential adverse effects during and after treatment is necessary. Administration of ketamine with other medications like monoaminergic antidepressants seems to be safe at low and even higher doses (Bartova et al. 2015), but ketamine metabolites might be reduced by diazepam, suggesting it might be beneficial to taper out or pause benzodiazepines during ketamine treatment (Idvall et al. 1983).
At long term follow ups there was no evidence of increased substance use, though studies on the addictive potential and long term effects of ketamine for the treatment of depression are lacking. From an investigation in 1285 chronic ketamine abusers, 17% of users developed dependence on ketamine. Regarding urinary symptoms, potentially from ketamine induced inflammation of the bladder, 26.6% recent ketamine users reported these and it was found that higher doses resulted in more symptoms. 51% reported improvement upon cessation of use and 3.8% reported prolonged deterioration after stopping ketamine (Winstock et al. 2012). Another study reported memory problems, schizophrenia-like symptoms, and inflammation of the stomach lining and bladder as main long-term side effects (Kalsi et al. 2011). It’s important to note that these patients are poly drug users and likely have differing side effect profiles from TRD patients due to the contexts in which the drug is used. This data does, however, suggest it might be safer to limit repetitive ketamine dosages to a maximum lifetime amount and not to perform excessive repetitive dosing to achieve response.
Discussion Treating Unipolar and Bipolar Depression with Ketamine
In the trial by Price et al. (2009), 81% of patients exhibited a drop of at average 2.08 points in the MADRS suicidal ideation subscale after a single infusion, resulting in post-infusion ratings of zero or one. The rapid antisuicidal effect of ketamine is also underlined by the results of Murrough et al. (2015), showing rapid reduction of acute suicidality in post-traumatic stress disorder, bipolar disorder, borderline personality disorder and MDD. Another meta-analysis further confirmed this effect and discussed the development and efficacy of further NMDA-receptor modulators (Newport et al. 2015). Due to the urgent need for those resistant to conventional antidepressant treatments, the glutamatergic neurotransmitter system has gained a lot of attention due to the “ketamine revolution”, and the pharmacological mechanisms of the drug have been investigated as a means to understand it’s role in the treatment of MDD and to explain the neurobiological basis of the disorder.
Ketamines primary method of action is blocking (antagonism) of the NMDA glutamate receptor. Simultaneously, it induces a substantial presynaptic release of glutamate by increasing the firing rate of glutamatergic neurons (Moghaddam, Adams, Verma, & Daly, 1997). This increase in glutamate release then favors AMPA glutamate receptors over NMDA receptors because the latter are blocked by ketamine, causing a greater throughput through the former and AMPA mediated synapse strengthening. These findings are consistent with the “glutaminergic model” of depression. Indeed, post-mortem and genetic studies show increased levels of glutamate and decreased levels of AMPA receptor subunits in the prefrontal cortex (Beneyto & Meador-Woodruff, 2006; Hashimoto, Sawa, & Iyo, 2007; Scarr, Pavey, Sundram,
MacKinnon, & Dean, 2003), and reduced NMDA receptor binding and subunit expression in the temporal and two frontal brain regions of individuals with MDD (Choudary et al., 2005; Nudmamud-Thanoi & Reynolds, 2004). Furthermore, a study applying magnetic resonance spectroscopy (MRS) found an association between lower glutamine/glutamate ratio in the prefrontal cortex and treatment response to ketamine, suggesting a lack of glial cells in MDD, because glutamine is mainly found in astrocytes (Salvadore et al. 2012). However, the connection of these findings to ketamine’s mechanisms of action is still debated and yet to be concretely drawn (Carlson et al. 2013).
Conclusion and Future Perspective on Treating Depression with Ketamine
The reviewed clinical trials demonstrate that intravenous and intranasal ketamine offer the possibility for safe and rapid relief of depression in unipolar and bipolar depressive disorder, with high response rates (up to 88%) and pronounced antisuicidal effects. It should be noted that the authors reported larger effects in open-label infusion studies, and easily detectable signs such as dizziness and dissociative symptoms make blinding difficult in ketamine studies. Future placebo-controlled studies should focus on active control or low-dose comparators. The main unresolved issue is that its effects are transient and, until now, there are no established methods to prolong ketamine’s antidepressant effects. Ketamine might, therefore, find its main application in acute antisuicidal and antidepressant treatment in psychiatric emergencies and in severely depressed subjects resistant to currently available antidepressants, as in relation to more invasive treatments for TRD such as electroconvulsive therapy (ECT), the remission of rather mild side effects after a short period of time is beneficial.
However, there are patient and cost friendly strategies to prolong efficacy such as repeated intranasal, sublingual or oral doses of ketamine (Schoevers et al. 2016). In this regard, potential adverse drug reactions such as tolerance or ketamine dependency must be carefully considered by experienced psychiatrists, administration has to be well monitored and potential long-term side effects have to be noted. Ketamine with its unique mechanisms of action has sparked the development of a new generation of antidepressant medications targeting the glutamatergic neurotransmitter system, with preliminary trials involving new NMDA-modulating agents yielding promising results (Newport et al. 2015). Additional therapeutic targets in the glutamate system might emerge, in search of ketamine’s distinct antidepressant mechanisms of action and shed more light into our understanding of MDD.
Aan het Rot, M., Collins, K. A., Murrough, J. W., Perez, A. M., Reich, D. L., Charney, D. S., & Mathew, S. J. (2010). Safety and efficacy of repeated-dose intravenous ketamine for treatment-resistant depression. Biological Psychiatry, 67( 2), 139-145. https://doi.org/10.1016/j.biopsych.2009.08.038
Balestri, M., Calati, R., Souery, D., Kautzky, A., Kasper, S., Montgomery, S., Zohar, J., Mendlewicz, J., & Serretti, A. (2016). Socio-demographic and clinical predictors of treatment resistant depression: A prospective European multicenter study. Journal of Affective Disorders, 189, 224-232. https://doi.org/10.1016/j.jad.2015.09.033
Bartova, L., Vogl, S. E., Stamenkovic, M., Praschak-Rieder, N., Naderi-Heiden, A., Kasper, S., & Willeit, M. (2015). Combination of intravenous S-ketamine and oral tranylcypromine in treatment-resistant depression: A report of two cases.European Neuropsychopharmacology, 25(11), 2183-2184. https://doi.org/10.1016/j.euroneuro.2015.07.021
Beneyto, M., & Meador-Woodruff, J. H. (2006). Lamina-specific abnormalities of AMPA receptor trafficking and signaling molecule transcripts in the prefrontal cortex in schizophrenia. Synapse, 60(8), 585-598. https://doi.org/10.1002/syn.20329
Berman, R. M., Cappiello, A., Anand, A., Oren, D. A., Heninger, G. R., Charney, D. S., & Krystal, J. H. (2000). Antidepressant effects of ketamine in depressed patients. Biological Psychiatry, 47(4), 351-354. https://doi.org/10.1016/s0006-3223(99)00230-9
Carlson, P. J., Diazgranados, N., Nugent, A. C., Ibrahim, L., Luckenbaugh, D. A., Brutsche, N., Herscovitch, P., Manji, H. K., Zarate, C. A., & Drevets, W. C. (2013). Neural correlates of rapid antidepressant response to ketamine in treatment-resistant unipolar depression: A preliminary positron emission tomography study. Biological Psychiatry, 73(12), 1213-1221. https://doi.org/10.1016/j.biopsych.2013.02.008
Choudary, P. V., Molnar, M., Evans, S. J., Tomita, H., Li, J. Z., Vawter, M. P., Myers, R. M., Bunney, W. E., Akil, H., Watson, S. J., & Jones, E. G. (2005). Altered cortical glutamatergic and GABAergic signal transmission with glial involvement in depression. Proceedings of the National Academy of Sciences, 102(43), 15653-15658. https://doi.org/10.1073/pnas.0507901102
Coyle, C. M., & Laws, K. R. (2015). The use of ketamine as an antidepressant: A systematic review and meta-analysis. Human Psychopharmacology: Clinical and Experimental, 30(3), 152-163. https://doi.org/10.1002/hup.2475
Diazgranados, N., Ibrahim, L., Brutsche, N. E., Newberg, A., Kronstein, P., Khalife, S., Kammerer, W. A., Quezado, Z., Luckenbaugh, D. A., Salvadore, G., Machado-Vieira, R., Manji, H. K., & Zarate, C. A. (2010). A randomized add-on trial of an N-methyl-D-aspartate antagonist in treatment-resistant bipolar depression. Archives of General Psychiatry, 67(8), 793. https://doi.org/10.1001/archgenpsychiatry.2010.90
Ghasemi, M., Kazemi, M. H., Yoosefi, A., Ghasemi, A., Paragomi, P., Amini, H., & Afzali, M. H. (2014). Rapid antidepressant effects of repeated doses of ketamine compared with electroconvulsive therapy in hospitalized patients with major depressive disorder. Psychiatry Research, 215( 2), 355-361. https://doi.org/10.1016/j.psychres.2013.12.008
Hashimoto, K., Sawa, A., & Iyo, M. (2007). Increased levels of glutamate in brains from patients with mood disorders. Biological Psychiatry, 62(11), 1310-1316. https://doi.org/10.1016/j.biopsych.2007.03.017
Idvall, J., Aronsen, K. F., Stenberg, P., & Paalzow, L. (1983). Pharmacodynamic and pharmacokinetic interactions between ketamine and diazepam. European Journal of Clinical Pharmacology, 24(3), 337-343. https://doi.org/10.1007/bf00610051
Kalsi, S. S., Wood, D. M., & Dargan, P. I. (2011). The epidemiology and patterns of acute and chronic toxicity associated with recreational ketamine use. Emerging Health Threats Journal, 4( 1), 7107. https://doi.org/10.3402/ehtj.v4i0.7107
Kautzky, A., Baldinger, P., Souery, D., Montgomery, S., Mendlewicz, J., Zohar, J., Serretti, A., Lanzenberger, R., & Kasper, S. (2015). The combined effect of genetic polymorphisms and clinical parameters on treatment outcome in treatment-resistant depression. European Neuropsychopharmacology, 25(4), 441-453. https://doi.org/10.1016/j.euroneuro.2015.01.001
Lapidus, K. A., Levitch, C. F., Perez, A. M., Brallier, J. W., Parides, M. K., Soleimani, L., Feder, A., Iosifescu, D. V., Charney, D. S., & Murrough, J. W. (2014). A randomized controlled trial of intranasal ketamine in major depressive disorder. Biological Psychiatry, 76(12), 970-976. https://doi.org/10.1016/j.biopsych.2014.03.026
Larkin, G. L., & Beautrais, A. L. (2011). A preliminary naturalistic study of low-dose ketamine for depression and suicide ideation in the emergency department. International Journal of Neuropsychopharmacology, 14(8), 1127-1131. https://doi.org/10.1017/s1461145711000629
Luckenbaugh, D. A., Ibrahim, L., Brutsche, N., Franco-Chaves, J., Mathews, D., Marquardt, C. A., Cassarly, C., & Zarate, C. A. (2012). Family history of alcohol dependence and antidepressant response to Ann-methyl-D-aspartate antagonist in bipolar depression. Bipolar Disorders, 14(8), 880-887. https://doi.org/10.1111/bdi.12003
Mathew, S. J., Murrough, J. W., Aan het Rot, M., Collins, K. A., Reich, D. L., & Charney, D. S. (2010). Riluzole for relapse prevention following intravenous ketamine in treatment-resistant depression: A pilot randomized, placebo-controlled continuation trial. International Journal of Neuropsychopharmacology, 13( 1), 71-82. https://doi.org/10.1017/s1461145709000169
Moghaddam, B., Adams, B., Verma, A., & Daly, D. (1997). Activation of Glutamatergic Neurotransmission by ketamine: A novel step in the pathway from NMDA receptor blockade to Dopaminergic and cognitive disruptions associated with the prefrontal cortex. The Journal of Neuroscience, 17(8), 2921-2927. https://doi.org/10.1523/jneurosci.17-08-02921.1997
Mrazek, D. A., Hornberger, J. C., Altar, C. A., & Degtiar, I. (2014). A review of the clinical, economic, and societal burden of treatment-resistant depression: 1996–2013. Psychiatric Services, 65( 8), 977-987. https://doi.org/10.1176/appi.ps.201300059
Murrough, J. W., Iosifescu, D. V., Chang, L. C., Al Jurdi, R. K., Green, C. E., Perez, A. M., Iqbal, S., Pillemer, S., Foulkes, A., Shah, A., Charney, D. S., & Mathew, S. J. (2013). Antidepressant efficacy of ketamine in treatment-resistant major depression: A two-site randomized controlled trial. American Journal of Psychiatry, 170( 10), 1134-1142. https://doi.org/10.1176/appi.ajp.2013.13030392
Murrough, J. W., Soleimani, L., DeWilde, K. E., Collins, K. A., Lapidus, K. A., Iacoviello, B. M., Lener, M., Kautz, M., Kim, J., Stern, J. B., Price, R. B., Perez, A. M., Brallier, J. W., Rodriguez, G. J., Goodman, W. K., Iosifescu, D. V., & Charney, D. S. (2015). Ketamine for rapid reduction of suicidal ideation: A randomized controlled trial. Psychological Medicine, 45(16), 3571-3580. https://doi.org/10.1017/s0033291715001506
Newport, D. J., Carpenter, L. L., McDonald, W. M., Potash, J. B., Tohen, M., & Nemeroff, C. B. (2015). Ketamine and other NMDA antagonists: Early clinical trials and possible mechanisms in depression. American Journal of Psychiatry, 172(10), 950-966. https://doi.org/10.1176/appi.ajp.2015.15040465
Nudmamud-Thanoi, S., & Reynolds, G. P. (2004). The NR1 subunit of the glutamate/NMDA receptor in the superior temporal cortex in schizophrenia and affective disorders. Neuroscience Letters, 372(1-2), 173-177. https://doi.org/10.1016/j.neulet.2004.09.035
Permoda-Osip, A., Dorszewska, J., Bartkowska-Sniatkowska, A., Chlopocka-Wozniak, M., & Rybakowski, J. (2013). Vitamin B12 level may be related to the efficacy of single ketamine infusion in bipolar depression. Pharmacopsychiatry, 46(06), 227-228. https://doi.org/10.1055/s-0033-1349861
Permoda-Osip, A., Kisielewski, J., Bartkowska-Sniatkowska, A., & Rybakowski, J. (2014). Single ketamine infusion and neurocognitive performance in bipolar depression. Pharmacopsychiatry, 48( 02), 78-79. https://doi.org/10.1055/s-0034-1394399
Permoda-Osip, A., Skibińska, M., Bartkowska-Śniatkowska, A., Kliwicki, S.,Chłopocka-Woźniak, M., & Rybakowski, J. (2014). Factors connected with efficacy of single ketamine infusion in bipolar depression. Psychiatria Polska, 48(1), 35-47. https://doi.org/10.12740/pp/21175
Price, R. B., Nock, M. K., Charney, D. S., & Mathew, S. J. (2009). Effects of intravenous ketamine on explicit and implicit measures of suicidality in treatment-resistant depression. Biological Psychiatry, 66(5), 522-526. https://doi.org/10.1016/j.biopsych.2009.04.029
Rybakowski, J. K., Permoda-Osip, A., Skibinska, M., Adamski, R., & Bartkowska-Sniatkowska, A. (2012). Single ketamine infusion in bipolar depression resistant to antidepressants: Are neurotrophins involved? Human Psychopharmacology: Clinical and Experimental, 28(1), 87-90. https://doi.org/10.1002/hup.2271
Salvadore, G., Van der Veen, J. W., Zhang, Y., Marenco, S., Machado-Vieira, R., Baumann, J., Ibrahim, L. A., Luckenbaugh, D. A., Shen, J., Drevets, W. C., & Zarate, C. A. (2011). An investigation of amino-acid neurotransmitters as potential predictors of clinical improvement to ketamine in depression. The International Journal of Neuropsychopharmacology, 15(08), 1063-1072. https://doi.org/10.1017/s1461145711001593
Scarr, E., Pavey, G., Sundram, S., MacKinnon, A., & Dean, B. (2003). Decreased hippocampal NMDA, but not kainate or AMPA receptors in bipolar disorder. Bipolar Disorders, 5(4), 257-264. https://doi.org/10.1034/j.1399-5618.2003.00024.x
Schak, K. M., Vande Voort, J. L., Johnson, E. K., Kung, S., Leung, J. G., Rasmussen, K. G., Palmer, B. A., & Frye, M. A. (2016). Potential risks of poorly monitored ketamine use in depression treatment. American Journal of Psychiatry, 173( 3), 215-218. https://doi.org/10.1176/appi.ajp.2015.15081082
Schosser, A., Serretti, A., Souery, D., Mendlewicz, J., Zohar, J., Montgomery, S., & Kasper, S. (2012). European group for the study of resistant depression (GSRD) — Where have we gone so far: Review of clinical and genetic findings.European Neuropsychopharmacology, 22(7), 453-468. https://doi.org/10.1016/j.euroneuro.2012.02.006
Schoevers RA, Chaves TV, Balukova SM, Rot MA, Kortekaas R. 2016. Oral ketamine for the treatment of pain and treatment-resistant depression†. Br J Psychiatry. 208:108–113.
Singh, J. B., Fedgchin, M., Daly, E., Xi, L., Melman, C., De Bruecker, G., Tadic, A., Sienaert, P., Wiegand, F., Manji, H., Drevets, W. C., & Van Nueten, L. (2016).
Intravenous esketamine in adult treatment-resistant depression: A double-blind, double-randomization, placebo-controlled study. Biological Psychiatry, 80( 6), 424-431. https://doi.org/10.1016/j.biopsych.2015.10.018
Sos P, Klirova M, Novak T, Kohutova B, Horacek J, Palenicek T. 2013. Relationship of ketamine’s antidepressant and psychotomimetic effects in unipolar depression. Neuro Endocrinol Lett. 34:287–293.
Thakurta, R. G., Ray, P., Kanji, D., Das, R., Bisui, B., & Singh, O. P. (2012). Rapid antidepressant response with ketamine: Is it the solution to resistant depression? Indian Journal of Psychological Medicine, 34( 1), 56-60. https://doi.org/10.4103/0253-7176.96161
Winstock, A. R., Mitcheson, L., Gillatt, D. A., & Cottrell, A. M. (2012). The prevalence and natural history of urinary symptoms among recreational ketamine users. BJU International, 110(11), 1762-1766. https://doi.org/10.1111/j.1464-410x.2012.11028.x
Zarate, C. A., Brutsche, N. E., Ibrahim, L., Franco-Chaves, J., Diazgranados, N.,Cravchik, A., Selter, J., Marquardt, C. A., Liberty, V., & Luckenbaugh, D. A. (2012). Replication of ketamine’s antidepressant efficacy in bipolar depression: A randomized controlled add-on trial. Biological Psychiatry, 71( 11), 939-946. https://doi.org/10.1016/j.biopsych.2011.12.010
Zarate, C. A., Singh, J. B., Carlson, P. J., Brutsche, N. E., Ameli, R., Luckenbaugh, D. A., Charney, D. S., & Manji, H. K. (2006). A randomized trial of an N-methyl-D-aspartate antagonist in treatment-resistant major depression. Archives of General Psychiatry, 63(8), 856. https://doi.org/10.1001/archpsyc.63.8.856