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.
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.