Psilocybin-Assisted Therapy for Depression Increases Amygdala Reactivity After Therapy, While Reducing Symptoms
Leor Roseman, M.Sc.
Objective: In recent years psychedelic-assisted therapy is experiencing a revival. Depressed subjects are known to have a hyperactive amygdala to fearful faces that is attenuated with SSRIs (Ma, 2015, Molecular psychiatry). We hypothesised that psilocybin-assisted therapy would change amygdala response to fearful faces after the therapy.
Methods: In this open-label study, 19 subjects, diagnosed with moderate to severe, treatment resistance depression, underwent psilocybin-assisted therapy with psychological support before, during and after these sessions. Subjects underwent fMRI scans before the first session and one day after second session. Neutral, fearful and happy faces were presented during the fMRI session and changes were measured in the amygdala.
Results: Right amygdala showed increased response to fearful and happy faces. Increased response for fearful compared to neutral faces in right amygdala was related to the improved therapeutic outcome 1-week after therapy.
Conclusion: While treatment-response was robust, the effect on right amygdala responsivity was in the opposite direction to effects of SSRI in the literature. Long-term antidepressant treatment leads to blunting of amygdala responses in the same emotional recognition task, where our psilocybin-assisted therapy enhanced amygdala responsivity. This difference might be related to the difference in the approach of both treatments: while the former attempts to ease negative emotions, the later attempts to confront and work through them. As the patients in this study showed rapid remission of symptoms, this suggests that blunting of emotional responsivity may not be necessary for therapeutic efficacy. Psychedelic-assisted therapy may provide a treatment avenue that preserves, and potentially even enhances emotional receptiveness.
Leor Roseman, M.Sc., studied Neuroscience at Tel Aviv University. Since June 2013, he is a Ph.D. student in neuroscience in the Beckley-Imperial Research Program under the supervision of Prof. David Nutt and Dr. Robin Carhart-Harris. Leor specializes in fMRI analysis techniques and his main research focus is neural correlates of psychedelic visual imagery and psilocybin-assisted therapy for treatment resistant depression.