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Shona Neehoff

Department of Psychological Medicine, University of Otago, Dunedin, New Zealand.

9 papers in the library · 217 citations · publishing 2017-2026

Papers

Effects of ketamine in patients with treatment-refractory generalized anxiety and social anxiety disorders: Exploratory double-blind psychoactive-controlled replication study

Journal of Psychopharmacology March 1, 2020 P. Glue, Shona Neehoff, A. Sabadel et al. 97 citations

In a double-blind, psychoactive-controlled study, 12 patients with treatment-resistant generalized anxiety and social anxiety disorders who were not currently depressed received ascending doses of ketamine (0.25, 0.5, 1 mg/kg) at weekly intervals, with midazolam 0.01 mg/kg randomly inserted as a control. Improvements in anxiety ratings occurred within an hour of ketamine dosing and persisted for up to one week. A dose-response profile was noted for anxiolytic effects, dissociative side effects, and changes in blood pressure and heart rate. Midazolam had minor brief effects on anxiety ratings. Ketamine was safe and well tolerated. Ketamine may be a potential therapeutic option for these patients.

Safety and efficacy of extended release ketamine tablets in patients with treatment-resistant depression and anxiety: open label pilot study

Therapeutic Advances in Psychopharmacology January 1, 2020 P. Glue, N. Medlicott, Shona Neehoff et al. 43 citations

An extended-release oral ketamine tablet was tested in seven patients with treatment-resistant depression and anxiety who had previously responded to subcutaneous ketamine. Over 96 hours, all patients showed more than 50% improvement in mood ratings, with gradual reductions in anxiety and depression. The tablet was safe and well tolerated, with no changes in vital signs and only one brief report of dissociation. The ratio of norketamine to ketamine increased over time, suggesting ketamine may induce its own metabolism. Serum BDNF concentrations did not change. The findings suggest extended-release oral ketamine may improve safety and tolerability while offering a slightly delayed onset of mood improvement compared to injected forms.

Effect of ketamine dose on self-rated dissociation in patients with treatment refractory anxiety disorders

Journal of Psychopharmacology October 1, 2017 Cameron Castle, Andrew Gray, Shona Neehoff et al. 20 citations

Ketamine produces dose-dependent dissociative symptoms in patients with treatment-resistant anxiety, while midazolam does not. The Clinician-Administered Dissociative States Scale (CADSS) shows high internal consistency (Cronbach alpha = 0.937) for measuring these symptoms, though it does not capture thought disorder. Individual items varied in their sensitivity to ketamine dose and magnitude of change. Removing items did not meaningfully improve the scale's reliability, and acceptable consistency remained even after excluding items unresponsive at lower doses. The CADSS is an internally consistent tool for assessing ketamine-induced dissociation in clinical trials for anxiety.

Six weeks open-label oral ketamine for patients with treatment-resistant depression, post-traumatic stress disorder, or obsessive-compulsive disorder.

Journal of psychopharmacology (Oxford, England) June 5, 2025 Ben Beaglehole, Paul Glue, Shona Neehoff et al. 19 citations

In an open-label extension of a prior crossover trial, oral ketamine was given for six weeks to people with treatment-resistant depression, post-traumatic stress disorder, or obsessive-compulsive disorder. Doses started at 1-1.5 mg/kg and increased to 1.5-2.5 mg/kg, taken one to three times per week. Symptom scores remained low throughout the six weeks, and the oral formulation was well tolerated with few side effects. The findings suggest that oral ketamine can sustain improvements in these treatment-resistant conditions and offers a practical alternative for maintenance therapy.

Anxiolytic effects of acute and maintenance ketamine, as assessed by the Fear Questionnaire subscales and the Spielberger State Anxiety Rating Scale.

Journal of psychopharmacology (Oxford, England) February 1, 2021 Dylan Truppman Lattie, Hayley Nehoff, Shona Neehoff et al. 13 citations

Ketamine produced rapid, dose-related reductions in fear and anxiety among patients with treatment-resistant anxiety disorders. In a study of 24 patients receiving short-term ascending subcutaneous doses followed by a 3-month maintenance phase, scores on all three Fear Questionnaire subscales (agoraphobia, social phobia, blood-injury phobia) and the Spielberger State Anxiety Inventory decreased quickly after acute dosing and continued to decline progressively during maintenance therapy. Ketamine appears to have broad, dose-related anti-phobic effects, suggesting potential for treating other phobic conditions.

Ketamine for treatment-resistant obsessive-compulsive disorder: Double-blind active-controlled crossover study.

Journal of psychopharmacology (Oxford, England) January 1, 2025 Ben Beaglehole, Paul Glue, Shona Neehoff et al. 12 citations

Ketamine reduces obsessive-compulsive symptoms more than a psychoactive control (fentanyl) in people with severe, treatment-resistant OCD. In a small double-blind trial, participants received a single intramuscular dose of either 0.5 mg/kg ketamine, 1.0 mg/kg ketamine, or 50 µg fentanyl. Both ketamine doses produced greater and dose-related reductions on the Yale-Brown Obsessive-Compulsive Scale, with effects separating from fentanyl within 1–2 hours and persisting for up to 168 hours. Ketamine caused short-term dissociative and cardiovascular effects; two of twelve participants dropped out due to not tolerating dissociation. The findings provide preliminary evidence for ketamine's efficacy and tolerability in an outpatient cohort.

Ketamine for treatment-resistant post-traumatic stress disorder: double-blind active-controlled randomised crossover study

BJPsych Open October 1, 2025 Ben Beaglehole, Paul Glue, Shona Neehoff et al. 5 citations

Intramuscular ketamine shows preliminary effectiveness and is well tolerated by people with posttraumatic stress disorder in a community setting. The findings are encouraging given the known limitations of existing treatments, but more research is needed to determine the best dosing schedule and long-term role of ketamine for PTSD.

Ketamine effects on EEG and their links to therapy differ across treatment-resistant major depression, post-traumatic stress disorder, and obsessive-compulsive disorder

The International Journal of Neuropsychopharmacology July 6, 2026 Shabah M. Shadli, Neda Nasrollahi, Calvin K. Young et al.

Ketamine at low doses (0.5-1.0 mg/kg I.M.) quickly reduces symptoms in treatment-resistant major depressive disorder (TR-MDD), post-traumatic stress disorder (TR-PTSD), and obsessive-compulsive disorder (TR-OCD), but its neural effects differ by diagnosis. EEG recordings of resting frontal activity before and after ketamine or fentanyl showed that TR-PTSD patients had dose- and band-frequency-dependent power changes (especially alpha at 0.5 mg/kg), while TR-MDD patients showed no such changes. TR-OCD responses differed qualitatively from both. Correlations between EEG power changes and symptom scale improvements varied by band and electrode across different disorder-specific scales. Ketamine's effects and their therapeutic links vary by brain site and frequency band depending on the DSM diagnosis, suggesting disorder-specific systems require a ketamine-sensitive factor to generate the disorder.