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Hinchcliffe JK, Stuart SA, Wood CM, Bartlett J, Kamenish K, Arban R, Thomas CW, Selimbeyoglu A, Hurley S, Hengerer B, Gilmour G, Robinson ES. Rapid-acting antidepressant drugs modulate affective bias in rats. Sci Transl Med 2024; 16:eadi2403. [PMID: 38198569 PMCID: PMC7615567 DOI: 10.1126/scitranslmed.adi2403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 12/13/2023] [Indexed: 01/12/2024]
Abstract
How rapid-acting antidepressants (RAADs), such as ketamine, induce immediate and sustained improvements in mood in patients with major depressive disorder (MDD) is poorly understood. A core feature of MDD is the prevalence of cognitive processing biases associated with negative affective states, and the alleviation of negative affective biases may be an index of response to drug treatment. Here, we used an affective bias behavioral test in rats, based on an associative learning task, to investigate the effects of RAADs. To generate an affective bias, animals learned to associate two different digging substrates with a food reward in the presence or absence of an affective state manipulation. A choice between the two reward-associated digging substrates was used to quantify the affective bias generated. Acute treatment with the RAADs ketamine, scopolamine, or psilocybin selectively attenuated a negative affective bias in the affective bias test. Low, but not high, doses of ketamine and psilocybin reversed the valence of the negative affective bias 24 hours after RAAD treatment. Only treatment with psilocybin, but not ketamine or scopolamine, led to a positive affective bias that was dependent on new learning and memory formation. The relearning effects of ketamine were dependent on protein synthesis localized to the rat medial prefrontal cortex and could be modulated by cue reactivation, consistent with experience-dependent neural plasticity. These findings suggest a neuropsychological mechanism that may explain both the acute and sustained effects of RAADs, potentially linking their effects on neural plasticity with affective bias modulation in a rodent model.
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Affiliation(s)
- Justyna K Hinchcliffe
- University of Bristol, School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, Bristol, BS8 1TD, UK
| | - Sarah A Stuart
- University of Bristol, School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, Bristol, BS8 1TD, UK
| | - Christian M Wood
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, CB3 2DY, UK
| | - Julia Bartlett
- University of Bristol, School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, Bristol, BS8 1TD, UK
| | - Katie Kamenish
- University of Bristol, School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, Bristol, BS8 1TD, UK
| | - Roberto Arban
- CNS Diseases Research, Boehringer Ingelheim GmbH & Co. KG, Biberach an der Riss, Germany
| | | | | | | | - Bastian Hengerer
- CNS Diseases Research, Boehringer Ingelheim GmbH & Co. KG, Biberach an der Riss, Germany
| | | | - Emma S.J. Robinson
- University of Bristol, School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, Bristol, BS8 1TD, UK
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Lucuta L, Maas-Gramlich A, Kraemer M, Andresen-Streichert H, Juebner M. Ketamine in DUID cases in the greater Cologne area. Forensic Sci Int 2024; 354:111905. [PMID: 38064774 DOI: 10.1016/j.forsciint.2023.111905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 11/20/2023] [Accepted: 12/01/2023] [Indexed: 01/12/2024]
Abstract
INTRODUCTION Ketamine is primarily used as an anaesthetic or for analgesics in medical treatment, but due to its dissociative and hallucinogenic effects, abuse has increased in the past years leading to several drug impaired driving cases. METHODS Eight DUID (driving under the influence of drugs) cases involving ketamine from two institutes of legal medicine over a period from January 2021 to January 2023 were evaluated. The cases were compared with regard to psychomotor impairments, adverse effects on driving performance and co-consumption of drugs. Analyses of ketamine were carried out by high performance liquid chromatography with diode array detection (HPLC-DAD). Other drugs of abuse were either detected via liquid chromatography with tandem mass spectromety (LC-MS/MS) and/or gas chromatography with (tandem) mass spectrometry (GC-MS(/MS)). RESULTS Ketamine plasma concentrations in a range of approx. 100-1200 ng/mL (mean: 510 ng/mL, median: 370 ng/mL) were detected. Co-consumption of at least one substance was ascertained in all cases. Besides driving impairments, recorded psychomotor impairments of the drivers comprised e.g. dilated pupils, missing or delayed pupil reactions, a slurred or decelerated speech, delayed reaction, lack of concentration, vertigo or agitation. DISCUSSION The observed peculiarities were in-line with literature data. However, the assessment and differentiation of ketamine-induced impairments was aggravated due to co-consumption of other drugs of abuse or pharmaceuticals in the herein investigated cases. Nevertheless, in two cases impairments can be attributed mainly to ketamine consumption since the co-consumed substances were only detected in low concentrations. CONCLUSION The presented cases provide additional data on psychomotor impairments observed in ketamine-related DUID cases. Limiting factors are co-consumption of substances, unknown habituation to drugs and the limited case number. Nevertheless, the results of this study are comparable with existing literature data. Since the abuse of ketamine has increased in the past years, these data will support forensic casework.
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Affiliation(s)
- L Lucuta
- Department of Toxicology, Institute of Legal Medicine, University of Cologne, Faculty of Medicine and University Hospital, Cologne, Germany.
| | - A Maas-Gramlich
- Institute of Forensic Medicine, Forensic Toxicology, University Hospital Bonn, Bonn, Germany
| | - M Kraemer
- Institute of Forensic Medicine, Forensic Toxicology, University Hospital Bonn, Bonn, Germany
| | - H Andresen-Streichert
- Department of Toxicology, Institute of Legal Medicine, University of Cologne, Faculty of Medicine and University Hospital, Cologne, Germany
| | - M Juebner
- Department of Toxicology, Institute of Legal Medicine, University of Cologne, Faculty of Medicine and University Hospital, Cologne, Germany
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Dai D, Miller C, Valdivia V, Boyle B, Bolton P, Li S, Seiner S, Meisner R. Neurocognitive effects of repeated ketamine infusion treatments in patients with treatment resistant depression: a retrospective chart review. BMC Psychiatry 2022; 22:140. [PMID: 35193541 PMCID: PMC8862573 DOI: 10.1186/s12888-022-03789-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 02/14/2022] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Ketamine has emerged as a rapid-acting antidepressant in treatment-resistant depression (TRD) increasingly used in non-research, clinical settings. Few studies, however, have examined neurocognitive effects of repeated racemic ketamine infusion treatments in patients with TRD. In an effort to identify potential effects after serial infusions, we conducted a retrospective chart review to identify statistically significant changes in cognition in patient undergoing serial intravenous infusions; concomitantly, we examined baseline cognition as potential predictor of anti-depressant potential. METHODS Twenty-two patients with TRD were examined after they finished the induction phase of 8-10 repeated intravenous ketamine infusions and completed the assessments of their depressive symptoms (measured by the 16-item Quick Inventory of Depressive Symptomatology-Self Report Scale: QIDS-SR16) and cognitive function (measured by the Montreal Cognitive Assessment: MoCA) before the first and the last ketamine treatments. RESULTS Repeated ketamine infusions administered through an escalating dose protocol with 8-10 infusion sessions produced a 47.2% reduction response in depression; there was no evidence of impairment as reflected in MoCA testing. There was a moderate association between baseline cognition and antidepressant response with a Pearson correlation of 0.453. CONCLUSION In this naturalistic sample of patients with TRD in our clinical service, repeated ketamine infusions significantly decreased depression symptoms without impairing cognitive performance. The baseline cognition may positively predict antidepressant responses of repeated ketamine treatment.
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Affiliation(s)
- Danika Dai
- grid.240206.20000 0000 8795 072XPsychiatric Neurotherapeutics Program, McLean Hospital, 115 Mill St, Belmont, MA 02478 USA
| | - Courtney Miller
- grid.240206.20000 0000 8795 072XPsychiatric Neurotherapeutics Program, McLean Hospital, 115 Mill St, Belmont, MA 02478 USA
| | - Violeta Valdivia
- grid.240206.20000 0000 8795 072XPsychiatric Neurotherapeutics Program, McLean Hospital, 115 Mill St, Belmont, MA 02478 USA ,grid.38142.3c000000041936754XDepartment of Psychiatry, Harvard Medical School, Boston, MA USA
| | - Brian Boyle
- grid.240206.20000 0000 8795 072XPsychiatric Neurotherapeutics Program, McLean Hospital, 115 Mill St, Belmont, MA 02478 USA ,grid.38142.3c000000041936754XDepartment of Psychiatry, Harvard Medical School, Boston, MA USA
| | - Paula Bolton
- grid.240206.20000 0000 8795 072XPsychiatric Neurotherapeutics Program, McLean Hospital, 115 Mill St, Belmont, MA 02478 USA
| | - Shuang Li
- Psychiatric Neurotherapeutics Program, McLean Hospital, 115 Mill St, Belmont, MA, 02478, USA. .,Department of Psychiatry, Harvard Medical School, Boston, MA, USA.
| | - Steve Seiner
- grid.240206.20000 0000 8795 072XPsychiatric Neurotherapeutics Program, McLean Hospital, 115 Mill St, Belmont, MA 02478 USA ,grid.38142.3c000000041936754XDepartment of Psychiatry, Harvard Medical School, Boston, MA USA
| | - Robert Meisner
- grid.240206.20000 0000 8795 072XPsychiatric Neurotherapeutics Program, McLean Hospital, 115 Mill St, Belmont, MA 02478 USA ,grid.38142.3c000000041936754XDepartment of Psychiatry, Harvard Medical School, Boston, MA USA
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Song B, Zhu J. A Novel Application of Ketamine for Improving Perioperative Sleep Disturbances. Nat Sci Sleep 2021; 13:2251-2266. [PMID: 34992482 PMCID: PMC8715868 DOI: 10.2147/nss.s341161] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 12/04/2021] [Indexed: 01/20/2023] Open
Abstract
Perioperative sleep disturbances are commonly observed before, during, and after surgery and can be caused by several factors, such as preoperative negative moods, general anesthetics, surgery trauma, and pain. Over the past decade, the fast-acting antidepressant effects of the N-methyl-D-aspartate (NMDA) receptor antagonist ketamine represent one of the most attractive discoveries in the field of psychiatry, such as antidepressant and anxiolytic effects. It is also widely used as a short-acting anesthetic and analgesic. Recent research has revealed new possible applications for ketamine, such as for perioperative sleep disorders and circadian rhythm disorders. Here, we summarize the risk factors for perioperative sleep disturbances, outcomes of perioperative sleep disturbances, and mechanism of action of ketamine in improving perioperative sleep quality.
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Affiliation(s)
- Bijia Song
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, Liaoning, People's Republic of China
| | - Junchao Zhu
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, Liaoning, People's Republic of China
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Matveychuk D, Thomas RK, Swainson J, Khullar A, MacKay MA, Baker GB, Dursun SM. Ketamine as an antidepressant: overview of its mechanisms of action and potential predictive biomarkers. Ther Adv Psychopharmacol 2020; 10:2045125320916657. [PMID: 32440333 PMCID: PMC7225830 DOI: 10.1177/2045125320916657] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 03/02/2020] [Indexed: 12/15/2022] Open
Abstract
Ketamine, a drug introduced in the 1960s as an anesthetic agent and still used for that purpose, has garnered marked interest over the past two decades as an emerging treatment for major depressive disorder. With increasing evidence of its efficacy in treatment-resistant depression and its potential anti-suicidal action, a great deal of investigation has been conducted on elucidating ketamine's effects on the brain. Of particular interest and therapeutic potential is the ability of ketamine to exert rapid antidepressant properties as early as several hours after administration. This is in stark contrast to the delayed effects observed with traditional antidepressants, often requiring several weeks of therapy for a clinical response. Furthermore, ketamine appears to have a unique mechanism of action involving glutamate modulation via actions at the N-methyl-D-aspartate (NMDA) and α -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, as well as downstream activation of brain-derived neurotrophic factor (BDNF) and mechanistic target of rapamycin (mTOR) signaling pathways to potentiate synaptic plasticity. This paper provides a brief overview of ketamine with regard to pharmacology/pharmacokinetics, toxicology, the current state of clinical trials on depression, postulated antidepressant mechanisms and potential biomarkers (biochemical, inflammatory, metabolic, neuroimaging sleep-related and cognitive) for predicting response to and/or monitoring of therapeutic outcome with ketamine.
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Affiliation(s)
- Dmitriy Matveychuk
- Department of Psychiatry, Neurochemical Research Unit, University of Alberta, Edmonton, Alberta, Canada
| | - Rejish K. Thomas
- Grey Nuns Community Hospital and Department of Psychiatry, University of Alberta, Edmonton, Alberta, Canada
| | - Jennifer Swainson
- Misericordia Community Hospital and Department of Psychiatry, University of Alberta, Edmonton, Alberta, Canada
| | - Atul Khullar
- Grey Nuns Community Hospital and Department of Psychiatry, University of Alberta, Edmonton, Alberta, Canada
| | - Mary-Anne MacKay
- Department of Psychiatry, Neurochemical Research Unit, University of Alberta, Edmonton, Alberta, Canada
| | - Glen B. Baker
- Department of Psychiatry, Neurochemical Research Unit, University of Alberta, 12-105B Clin Sci Bldg, Edmonton, Alberta T6G 2G3, Canada
| | - Serdar M. Dursun
- Department of Psychiatry, Neurochemical Research Unit, University of Alberta, Edmonton, Alberta, Canada
- Grey Nuns Community Hospital, Edmonton, Alberta, Canada
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Driving Simulator Performance After Administration of Analgesic Doses of Ketamine With Dexmedetomidine or Fentanyl. J Clin Psychopharmacol 2020; 39:446-454. [PMID: 31433347 DOI: 10.1097/jcp.0000000000001101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE/BACKGROUND As a sole agent, ketamine acutely compromises driving ability; however, performance after coadministration with the adjuvant sedating agents dexmedetomidine or fentanyl is unclear. METHODS/PROCEDURES Using a randomized within-subject design, 39 participants (mean ± SD age, 28.4 ± 5.8 years) received 0.3 mg/kg bolus followed by 0.15 mg kg h infusion of ketamine (3-hour duration), in addition to either (i) 0.7 μg kg h infusion of dexmedetomidine for 1.5 hours (n = 19; KET/DEX) or (ii) three 25 μg fentanyl injections for 1.5 hours (n = 20; KET/FENT). Whole blood drug concentrations were determined during ketamine only, at coadministration (KET/DEX or KET/FENT) and at 2 hours after treatment. Subjective effects were determined using a standardized visual analog scale. Driving performance was assessed at baseline and at posttreatment using a validated computerized driving simulator. Primary outcomes included SD of lateral position (SDLP) and steering variability (SV). FINDINGS/RESULTS Administration of ketamine with dexmedetomidine but not fentanyl significantly increased SDLP (F1,18 = 22.60, P < 0.001) and reduced SV (F1,18 = 164.42, P < 0.001) 2 hours after treatment. These deficits were comparatively greater for the KET/DEX group than for the KET/FENT group (t37 = -5.21 [P < 0.001] and t37 = 5.22 [P < 0.001], (respectively). For the KET/DEX group, vehicle control (SV) and self-rated performance (visual analog scale), but not SDLP, was inversely associated with ketamine and norketamine blood concentrations (in nanograms per milliliter). Greater subjective effects were moderately associated with driving deficits. IMPLICATIONS/CONCLUSIONS Driving simulator performance is significantly compromised after coadministration of analgesic range doses of ketamine with dexmedetomidine but not fentanyl. An extended period of supervised driver abstinence is recommended after treatment, with completion of additional assessments to evaluate home readiness.
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Hayley AC, Green M, Downey LA, Keane M, Kenneally M, Adams M, Shehabi Y. Neurocognitive performance under combined regimens of ketamine-dexmedetomidine and ketamine-fentanyl in healthy adults: A randomised trial. Prog Neuropsychopharmacol Biol Psychiatry 2019; 94:109647. [PMID: 31095995 DOI: 10.1016/j.pnpbp.2019.109647] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 03/01/2019] [Accepted: 05/08/2019] [Indexed: 11/24/2022]
Abstract
Analgesic doses of ketamine affects neurocognition; however, deficits under co-administration regimens are unknown. This study evaluated the effects of ketamine, alone and in combination with dexmedetomidine or fentanyl on neurocognition. Using a randomised, within-subjects gender stratified design, 39 participants (mean age = 28.4, SD ± 5.8) received a ketamine bolus of 0.3 mg/kg followed by 0.15 mg/kg/h infusion of ketamine (3 h duration). At 1.5 h post-ketamine infusion commencement, participants received either: i) 0.7 μg/kg/h infusion of dexmedetomidine (n = 19) (KET/DEX) or (ii) three 25 μg fentanyl injections over 1.5 h (n = 20) (KET/FENT). Reaction and Movement time (RTI, Simple and 5Choice), Visuospatial Working Memory (SWM) and Verbal Recognition Memory (VRM) were assessed using the Cambridge Neuropsychological Test Automated Battery (CANTAB). Whole blood drug concentrations were determined during ketamine-only infusion, at co-administration (KET/DEX or KET/FENT) and at 2-h post-treatment. Ketamine-only administration impaired psychomotor response speed (Simple and 5Choice) and impaired memory (all p < .001), however did not alter executive function abilities. Independent of sedation, co-administration of dexmedetomidine produced synergistic performance and memory deficits which persisted at post-treatment (KET/DEX) (all p < .001), and were comparatively greater than for KET/FENT (all p < .05). Ketamine, norketamine and dexmedetomidine concentrations were modestly associated with reduced psychomotor speed and accuracy (all p < .05), and an inverse relationship was found between blood concentrations of ketamine, norketamine and dexmedetomidine and performance on memory tasks. Co-administration of ketamine with dexmedetomidine but not with fentanyl exerts synergistic effects on psychomotor performance and memory without executive dysfunction. Assessment of these effects in clinical groups is warranted.
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Affiliation(s)
- Amie C Hayley
- Centre for Human Psychopharmacology, Swinburne University of Technology, Hawthorn, Australia; Institute for Breathing and Sleep, Austin Hospital, Melbourne, Australia.
| | - Maja Green
- Critical Care and Perioperative Medicine, School of Clinical Sciences, Monash University, Melbourne, South Australia, Australia; Department of Oncology, Monash Health Translation Precinct, Monash University, Clayton, Australia
| | - Luke A Downey
- Centre for Human Psychopharmacology, Swinburne University of Technology, Hawthorn, Australia; Institute for Breathing and Sleep, Austin Hospital, Melbourne, Australia
| | - Michael Keane
- Centre for Human Psychopharmacology, Swinburne University of Technology, Hawthorn, Australia; Critical Care and Perioperative Medicine, School of Clinical Sciences, Monash University, Melbourne, South Australia, Australia
| | | | - Mark Adams
- Critical Care and Perioperative Medicine, School of Clinical Sciences, Monash University, Melbourne, South Australia, Australia
| | - Yahya Shehabi
- Critical Care and Perioperative Medicine, School of Clinical Sciences, Monash University, Melbourne, South Australia, Australia
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Enomoto T, Ikeda K. [Translational behavioral research using common marmosets in the psychiatric field]. Nihon Yakurigaku Zasshi 2019; 153:28-34. [PMID: 30643089 DOI: 10.1254/fpj.153.28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The drug discovery activities for novel compounds with the superior efficacies to current drugs have been largely unsuccessful in the psychiatric field. One of the main reasons is the lack of appropriate behavioral assays and animal models for psychiatric disorders. Since the prefrontal cortex has great roles in their pathophysiology, non-human primate common marmosets with the well-developed prefrontal cortex would be useful as experimental animals in the future translational research. To measure objectively and quantitatively the psychiatric symptoms like motivational deficits, negative affective bias and cognitive impairments in patients with schizophrenia or major depressive disorder, the clinical laboratory tasks have been developed. The development of marmoset behavioral paradigms, which may correspond to the clinical laboratory tasks, have been progressed for the translational research. On the other hand, there are still limitations to develop the marmoset models resembling the pathophysiology of psychiatric disorders. We review the current state and future perspective of translational behavioral research using marmosets.
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Affiliation(s)
- Takeshi Enomoto
- Higher Brain Function Research, Drug Research Division, Sumitomo Dainippon Pharma Co., Ltd
| | - Kazuhito Ikeda
- Higher Brain Function Research, Drug Research Division, Sumitomo Dainippon Pharma Co., Ltd
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The acute and residual effects of escalating, analgesic-range doses of ketamine on driving performance: A simulator study. Prog Neuropsychopharmacol Biol Psychiatry 2018; 86:83-88. [PMID: 29782960 DOI: 10.1016/j.pnpbp.2018.05.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 05/17/2018] [Accepted: 05/17/2018] [Indexed: 10/16/2022]
Abstract
Ketamine hydrochloride elicits potent psychotomimetic and neurobehavioural effects which make it incompatible with driving; however, the direct effect on driving performance is yet to be assessed. Using an open label, within-subjects protocol, 15 males and 5 females (mean age = 30.8 years) were administered three fixed, stepwise increasing sub-anaesthetic doses of intravenous (IV) ketamine solution [(i) 8 mg/h IV infusion plus 30 mg bolus, (ii) 12 mg/h IV infusion and (iii) 20 mg/h infusion]. Whole blood ketamine and norketamine concentrations were determined at each treatment step and at 2 h post-infusion. Driving performance was assessed at baseline, at each treatment step and at 2 h post-treatment using a validated computerised driving simulator. Standard Deviation of Lateral Position (SDLP) and Steering Variability (SV) were assessed. Linear Fixed Effect Modelling indicated a main effect for time (dose) for SDLP (F[4,72] = 33.22, p < 0.0001) and SV (F[4,72] = 4.65, p < 0.002). Post-hoc analyses revealed significant differences from baseline at each treatment step for SDLP (all p < 0.001), and for 12 mg/h treatment step for SV (p = 0.049). Post-treatment driving performance returned to baseline levels. Weak positive linear associations were observed between SDLP and whole blood ketamine concentrations (R2 = 0.11, β = 29.96, p = 0.001) and norketamine (R2 = 0.09, β = 28.87, p = 0.003). These findings suggest that even under highly controlled conditions, ketamine intoxication significantly alters simulated driving performance. At the highest dose, ketamine produced changes to SDLP considered incompatible with safe driving, highlighting how ketamine consumption may translate to an increased risk of road trauma.
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