Dr. Robin Carhart-Harris is a faculty member in the Department of Medicine at Imperial College London and the head of the Imperial Psychedelic Research Group. His research interests center on understanding the effects psychedelic drugs have on the mind and their therapeutic uses.
Dr. Carhart-Harris was inspired to study psychedelics while in graduate school after reading Stanislav Grof’s Realms of the Human Unconscious: Observations from LSD Research. Because of this experience, he contacted Dr. David Nutt, then head of the psychopharmacology unit at the University of Bristol. He joined Nutt’s research team to pursue his PhD studying MDMA (3,4-Methyl enedioxy methamphetamine). He received his doctorate from the University of Bristol in 2009.
Visualizing the Brain
The psychedelics LSD and psilocybin are the primary focus of Dr. Carhart-Harris’s research. His work with LSD1–5 is highlighted by a pioneering 2016 study that looked at the human brain in real time under the influence of LSD.5 Using multimodal neural imaging techniques, the study found marked changes in electrical activity, blood flow, and communication patterns in the brain. The study also found a strong relationship between changes in brain function and the subject’s reporting of “ego dissolution” and “altered meaning.”
In 2012, Dr. Carhart-Harris did a similar study using functional magnetic resonance imaging (fMRI) to look at the effects of psilocybin on the human brain.6 The subjects in this study experienced profound changes in consciousness. The fMRI revealed their subjective experiences were accompanied by decreased activity and connectivity in the key connector hubs of the brain. These areas included the prefrontal cortex, thalamus, and the anterior and posterior cingulate cortex. This gave the subjects what the researchers described as “a state of unconstrained cognition.”
Using Psilocybin for Treatment-Resistant Depression
Over the years, Dr. Carhart-Harris has worked extensively with psilocybin. 7–16 He has recently focused on investigating its therapeutic capabilities for treatment-resistant depression (TRD). The work began with a feasibility study in 2016.8 Psilocybin was well-tolerated by all study subjects and they experienced no adverse or unexpected events. Subjects felt the effects 30-60 minutes after dosing. The effects peaked at 2-3 hours and subsided after 6 hours. The results showed their depression was markedly reduced at 1 week and 3 months of high dose (25 mg) treatment. The subjects also experienced long-lasting improvement in their depressive symptoms and their ability to enjoy life.
In 2017, additional studies using psilocybin for TRD showed patients experienced more ‘connectedness’ to the world and other people and emotional ‘acceptance’ than when they used traditional medications and treatments for depression.15 Using fMRI scans, Dr. Carhart-Harris also discovered using psilocybin-assisted therapy in people with TRD revives their ability to connect with their emotions.17 This effect was seen on the fMRIs as increased activity in the amygdala. The participants in the study also showed “rapid and enduring improvements in depressive symptoms post psilocybin” which correlated with increased activity in the amygdala.
Another fMRI study done in 2017 was the first of its kind to look at the after-treatment effects of psilocybin on the brains of people with TRD.14 One week after treatment, the fMRI scans found decreased cerebral blood flow in the temporal cortex and amygdala. This correlated with reduced depressive symptoms reported by the subjects. There was also an increase in the resting-state functional connectivity of the subject’s brains within an area called the default-mode network (DMN). These after-treatment findings differ from the changes seen in the brain while TRD patients are under the influence of psilocybin. The researchers propose psilocybin causes a therapeutic ‘reset’ in the brain.
In 2018, more work by Dr. Carhart-Harris gives additional insights into psilocybin-assisted therapy for TRD. One study found the quality of the psilocybin psychedelic experience can predict how effective the patient’s therapy and long-term mental health changes will be.16 Another study suggests psilocybin-assisted therapy may change a person’s attitudes and beliefs in the long-term.18
In 2016, Dr. Carhart-Harris made a popular TEDx talk called Psychedelics: Lifting the veil.