Ketamine-assisted psychotherapy in a portuguese public hospital
Background: Ketamine is an N-methyl-d-aspartate antagonist which has emerged as a promising treatment option for several mental health conditions, such as addiction and depression. Research has shown that it causes an acute disruption of the brain's large-scale functional networks and a sub-acute increase in neuroplasticity. Ketamine has dose-dependent psychedelic effects and recent studies have suggested that higher-than-typical doses (0.75-1.0 mg/kg) may be more effective in treatment-resistant depression (TRD). It has also been reported that greater antidepressant response with ketamine was correlated with psychological experiences of unity and insight, an effect which has also been found when ketamine is used for the treatment of cocaine addiction. Using the predictive processing framework, we recently proposed that ketamine may cause a dose-dependent acute relaxation of overly precise beliefs about the narrative self (experienced as ego dissolution), entailing belief-updating and neuronal activity that drives activity-dependent plasticity (for which neuroplasticity plays a permissive role). This neurophysiological and psychological destabilization in order to break reinforced patterns of thought, emotion and behaviour provides a rationale for combining ketamine with a short-term psychotherapeutic intervention.
Methods: We will report the results of a case series of 12 patients with TRD who were treated with ketamine-assisted psychotherapy in a public hospital in Lisbon. Each patient completed 5 to 8 weekly ketamine sessions (mean=6 sessions; dose range 0,5-1,5 mg/kg IM) with psychotherapy on the following day. Depressive symptoms were assessed using the Beck Depression Inventory-2. The acute psychological effects of ketamine were assessed at the end of the drug administation sessions using the Ego Dissolution Inventory and by the Emotional Breakthrough Inventory. Insight at the end of treatment was assessed by the Psychological Insight Scale.
Results: At the end of treatment, we found a response rate of 67% and a remission rate of 58%. At 3-month follow-up, 50% of the sample maintained remission. We found a positive correlation between the intensity of ego dissolution at session 3 and reduction of depressive symptoms at the end of treatment. Ego dissolution at session 3 was correlated with psychological insight at the end of treatment. Finally, we found a correlation between psychological insight and reduction in depressive symptoms.
Conclusions: These results highlight the potential benefit of combining ketamine with a psychotherapeutic intervention to take full advantage of its properties.
