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Psychiatry

How AI and language can help predict psychedelic treatment outcomes

Language is increasingly being used as a diagnostic tool in biomedical research and has recently begun to be leveraged in psychedelic research. It turns out analysing language through machine learning can help increase diagnostic accuracy and predict psychedelic treatment outcomes, which will play an important role in the future of psychedelic research.

Author: Maxim Siegel
Illustration: Anna Temczuk

Language as a diagnostic tool

Sigmund Freud and Carl Jung are arguably the most influential figures of the 20th century when it comes to psychological functioning and the human mind. Although their theories about the psyche eventually differed, they both considered language as a manifestation of the unconscious. Indeed, Freudian psychoanalysis proposed free association as a way of gaining access to unconscious processes, while Jungian psychology considered every act of speech as a psychic event, with each word carrying particular archetypal energies. Fast forward 100 years, innovations in biomedical science and technology have transformed language into a diagnostic tool for both affective and degenerative neuropathology, and language is increasingly being used as such in psychedelic research. 

Natural Language Processing, also known as NLP, is a field combining linguistics, computer science, and artificial intelligence. It applies computational techniques to the analysis and synthesis of natural language. One of the problems with natural language is that it often contains ambiguities in meaning, also known as semantic ambiguities, which are easily detectable by humans but not so much by computers. Luckily, models such as distributional semantics, count vectorisation and encoder-decoder modeling help decipher semantic ambiguities. Since its development, NLP has predominantly been used as an automation tool for google searches, spam email categorisation, voice recognition, and translations, but it is increasingly being used as a diagnostic tool in medicine. 

A few years ago, a team of researchers in Canada were able to identify linguistic features within narrative speech that were specific to Alzheimer’s Disease. Semantic impairment, acoustic abnormality, and syntactic impairment were all factors enabling the accurate identification of Alzheimer’s, based on patients’ short descriptions of a picture.

This led to the realisation that beyond its unconscious, psyche-revealing properties, natural language might also possess neuropathology-revealing properties. So what if language could be used as a biomarker for psychosis or affective disorders? More importantly, what if language could be used as a predictor of treatment outcome? It turns out these tools have already begun to be leveraged in psychedelic research.

Around four years ago, a team of researchers from Buenos Aires University’s Applied Artificial Intelligence Lab and Imperial College London’s Psychedelic Research Group decided to test a combination of NLP and machine learning. They tested this combination both as a diagnostic tool for patients suffering from treatment-resistant depression, and as a predictor of treatment outcome following a psilocybin challenge. 

Participants first underwent a psychological interview known as an Autobiographical Memory Test, an interview used to assess the degree of specificity of autobiographical memory. This interview was analysed using an NLP method known as Emotional Analysis, which quantifies the emotional content of spoken or written text. The NLP output was then fed as input into a machine learning algorithm, known as a classifier, trained at recognising depressed patients. 

On the basis of emotional analysis and specifically the use of positive words, which were less frequently used in depressed patients compared to healthy controls, the classifier was able to differentiate between depressed patients and healthy controls with a mean accuracy of 82.85%, close to 15% better than the mean accuracy of general practitioners unassisted by screening tests.  

Accurate Predictions

Perhaps more impressive than its ability to differentiate between depressed patients and healthy controls, was the classifier’s ability to differentiate between treatment responders and non-responders. Based on the same parameters it had previously used to diagnose depressed patients (NLP output and positive word frequency), the classifier was able to predict which patients would respond to a psilocybin challenge and which would not. 

Only the patients identified as “responders” were given the psilocybin challenge, whereas the “non-responders” were removed from the treatment arm. This manoeuvre had the effect of improving overall treatment response by 34% compared to the original experiment.  

Last year, a team at Johns Hopkins University used a similar approach to predict changes in substance use following a psychedelic challenge. They recruited individuals who reported quitting or reducing a number of addictive drugs following a psychedelic experience, and asked them for a verbal narrative of the experience.

They used an NLP method known as Latent Semantic Analysis, which analyses the relationship between semantic structures across different texts, to derive topic models that described the psychedelic narratives. These topic models were fed as input into three different machine learning algorithms to predict long-term drug reduction. The machine learning algorithms had an average predictive accuracy of 65%, and additional analyses revealed between-group differences in psychedelic experience narratives based on the derived topic models.

John Hopkins’ semantic analysis of psychedelic narratives and Buenos Aires University’s use of machine learning to identify patients suffering from depression, are two early but powerful examples of the ways in which language can be leveraged in psychedelic research through new technology.

The combination of NLP and machine learning as methods to analyse language have reliably shown their value as both diagnostic and predictive tools, and can be used to optimise clinical trials. They allow for a more personalised treatment, whereby non-responders are spared the emotional rollercoaster of an acute psychedelic experience. 

Freudian psychoanalysis, Jungian psychology and NLP share the conception that hidden semantic structures within language are associated with underlying processes, whether psychological, social, or physiological. A century ago, language was the glass through which Freud saw the unconscious mind. Today, language analysed by machine learning may very well be one of the prisms through which we can come to understand the psychedelic experience.

References:

1. N.B. This is different from “Neuro-linguistic programming” (NLP), which is a form of psychotherapy developed in California in the 1970s, mainly used as a method of personal development by promoting skills including communication.

2. Fraser, K. C., Meltzer, J. A., & Rudzicz, F. (2016). Linguistic Features Identify Alzheimer’s Disease in Narrative Speech. Journal of Alzheimer’s disease : JAD, 49(2), 407–422. https://doi.org/10.3233/JAD-150520

3. Carrillo, F., Sigman, M., Fernández Slezak, D., Ashton, P., Fitzgerald, L., Stroud, J., Nutt, D. J., & Carhart-Harris, R. L. (2018). Natural speech algorithm applied to baseline interview data can predict which patients will respond to psilocybin for treatment-resistant depression. Journal of affective disorders, 230, 84–86. https://doi.org/10.1016/j.jad.2018.01.006

4. Carey, M., Jones, K., Meadows, G., Sanson-Fisher, R., D’Este, C., Inder, K., Yoong, S. L., & Russell, G. (2014). Accuracy of general practitioner unassisted detection of depression. The Australian and New Zealand journal of psychiatry, 48(6), 571–578.

5. The original experiment consisted of a combination of psychotherapy and pharmacological treatment with psilocybin that resulted in 41% treatment response. By differentiating between treatment responders and non-responders this experiment resulted in 75% treatment response.

6. Cox, D. J., Garcia-Romeu, A., & Johnson, M. W. (2021). Predicting changes in substance use following psychedelic experiences: natural language processing of psychedelic session narratives. The American journal of drug and alcohol abuse, 47(4), 444–454. https://doi.org/10.1080/00952990.2021.1910830

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Safety of ibogaine administration in detoxification of opioid-dependent individuals: a descriptive open-label observational study

Abstract

Background and aims: Ibogaine is an indole alkaloid used in rituals of the African Bwiti tribe. It is also used in non-medical settings to treat addiction. However, ibogaine has been linked to several deaths, mainly due to cardiac events called torsades des pointes preceded by QTc prolongation as well as other safety concerns. This study aimed to evaluate the cardiac, cerebellar and psychomimetic safety of ibogaine in patients with opioid use disorder.

Design: A descriptive open-label observational study.

Setting: Department of psychiatry in a university medical center, the Netherlands.

Participants: Patients with opioid use disorder (n = 14) on opioid maintenance treatment with a lasting wish for abstinence, who failed to reach abstinence with standard care.

Intervention and measurements: After conversion to morphine-sulphate, a single dose of ibogaine-HCl 10 mg/kg was administered and patients were monitored at regular intervals for at least 24 hours assessing QTc, blood pressure and heart rate, scale for the assessment and rating of ataxia (SARA) to assess cerebellar side effects and the delirium observation scale (DOS) to assess psychomimetic effects.

Findings: The maximum QTc (Fridericia) prolongation was on average 95ms (range 29-146ms). Fifty percent of subjects reached a QTc of over 500ms during the observation period. In six out 14 subjects prolongation above 450ms lasted beyond 24 hours after ingestion of ibogaine. No torsades des pointes were observed. Severe transient ataxia with inability to walk without support was seen in all patients. Withdrawal and psychomimetic effects were mostly well-tolerated and manageable (11/14 did not return to morphine within 24 hours, DOS scores remained below threshold).

Conclusions: This open-label observational study found that ibogaine treatment of patients with opioid use disorder can induce a clinically relevant but reversible QTc prolongation, bradycardia, and severe ataxia.

Knuijver, T., Schellekens, A., Belgers, M., Donders, R., van Oosteren, T., Kramers, K., & Verkes, R. (2022). Safety of ibogaine administration in detoxification of opioid-dependent individuals: a descriptive open-label observational study. Addiction (Abingdon, England), 117(1), 118–128. https://doi.org/10.1111/add.15448

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Risk assessment of ayahuasca use in a religious context: self-reported risk factors and adverse effects

Abstract

Objective: Whether for spiritual, recreational, or potential therapeutic use, interest in ayahuasca has grown remarkably. Ayahuasca’s main active substances are N,N-dimethyltryptamine and certain monoamine oxidase inhibitor β-carbolines. Possible drug interactions are a major concern, and research is lacking in this area. The objective of this study was to evaluate the safety of ritual ayahuasca use regarding adverse effects and risk factors.

Methods: In this cross-sectional study, ayahuasca users from a religious institution answered an online questionnaire about its safety. Adverse effects, safety measures, and possible risk factors (psychiatric diagnosis and medications) were investigated.

Results: The most frequent adverse effects among the 614 participants were transient gastrointestinal effects (nausea and vomiting). Fifty participants self-reported a psychiatric diagnosis (depression and anxiety were the most prevalent), and these participants experienced adverse effects more frequently. Psychiatric medication use was reported by 31 participants. No indication of increased adverse effects due to drug-drug interactions was found.

Conclusion: A minority of participants reported being very negatively affected by persistent adverse effects. Psychiatric medication use while participating in ayahuasca rituals was not associated with increased adverse effects. For the most part, the institution’s practices seem sufficient to prevent exacerbated reactions. Future studies may focus on negatively affected users.

Durante, Í., Dos Santos, R. G., Bouso, J. C., & Hallak, J. E. (2021). Risk assessment of ayahuasca use in a religious context: self-reported risk factors and adverse effects. Revista brasileira de psiquiatria (Sao Paulo, Brazil : 1999), 43(4), 362–369. https://doi.org/10.1590/1516-4446-2020-0913

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Effects of Psilocybin-Assisted Therapy on Major Depressive Disorder: A Randomized Clinical Trial

Abstract

Importance: Major depressive disorder (MDD) is a substantial public health burden, but current treatments have limited effectiveness and adherence. Recent evidence suggests that 1 or 2 administrations of psilocybin with psychological support produces antidepressant effects in patients with cancer and in those with treatment-resistant depression.

Objective: To investigate the effect of psilocybin therapy in patients with MDD.

Design, setting, and participants: This randomized, waiting list-controlled clinical trial was conducted at the Center for Psychedelic and Consciousness Research at Johns Hopkins Bayview Medical Center in Baltimore, Maryland. Adults aged 21 to 75 years with an MDD diagnosis, not currently using antidepressant medications, and without histories of psychotic disorder, serious suicide attempt, or hospitalization were eligible to participate. Enrollment occurred between August 2017 and April 2019, and the 4-week primary outcome assessments were completed in July 2019. A total of 27 participants were randomized to an immediate treatment condition group (n = 15) or delayed treatment condition group (waiting list control condition; n = 12). Data analysis was conducted from July 1, 2019, to July 31, 2020, and included participants who completed the intervention (evaluable population).

Interventions: Two psilocybin sessions (session 1: 20 mg/70 kg; session 2: 30 mg/70 kg) were given (administered in opaque gelatin capsules with approximately 100 mL of water) in the context of supportive psychotherapy (approximately 11 hours). Participants were randomized to begin treatment immediately or after an 8-week delay.

Main outcomes and measures: The primary outcome, depression severity was assessed with the GRID-Hamilton Depression Rating Scale (GRID-HAMD) scores at baseline (score of ≥17 required for enrollment) and weeks 5 and 8 after enrollment for the delayed treatment group, which corresponded to weeks 1 and 4 after the intervention for the immediate treatment group. Secondary outcomes included the Quick Inventory of Depressive Symptomatology-Self Rated (QIDS-SR).

Results: Of the randomized participants, 24 of 27 (89%) completed the intervention and the week 1 and week 4 postsession assessments. This population had a mean (SD) age of 39.8 (12.2) years, was composed of 16 women (67%), and had a mean (SD) baseline GRID-HAMD score of 22.8 (3.9). The mean (SD) GRID-HAMD scores at weeks 1 and 4 (8.0 [7.1] and 8.5 [5.7]) in the immediate treatment group were statistically significantly lower than the scores at the comparable time points of weeks 5 and 8 (23.8 [5.4] and 23.5 [6.0]) in the delayed treatment group. The effect sizes were large at week 5 (Cohen d = 2.5; 95% CI, 1.4-3.5; P < .001) and week 8 (Cohen d = 2.6; 95% CI, 1.5-3.7; P < .001). The QIDS-SR documented a rapid decrease in mean (SD) depression score from baseline to day 1 after session 1 (16.7 [3.5] vs 6.3 [4.4]; Cohen d = 2.6; 95% CI, 1.8-3.5; P < .001), which remained statistically significantly reduced through the week 4 follow-up (6.0 [5.7]; Cohen d = 2.3; 95% CI, 1.5-3.0; P < .001). In the overall sample, 17 participants (71%) at week 1 and 17 (71%) at week 4 had a clinically significant response to the intervention (≥50% reduction in GRID-HAMD score), and 14 participants (58%) at week 1 and 13 participants (54%) at week 4 were in remission (≤7 GRID-HAMD score).

Conclusions and relevance: Findings suggest that psilocybin with therapy is efficacious in treating MDD, thus extending the results of previous studies of this intervention in patients with cancer and depression and of a nonrandomized study in patients with treatment-resistant depression.

Trial registration: ClinicalTrials.gov Identifier: NCT03181529.

Davis, A. K., Barrett, F. S., May, D. G., Cosimano, M. P., Sepeda, N. D., Johnson, M. W., Finan, P. H., & Griffiths, R. R. (2021). Effects of Psilocybin-Assisted Therapy on Major Depressive Disorder: A Randomized Clinical Trial. JAMA psychiatry, 78(5), 481–489. https://doi.org/10.1001/jamapsychiatry.2020.3285

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Naturalistic Use of Mescaline Is Associated with Self-Reported Psychiatric Improvements and Enduring Positive Life Changes

Abstract

Mescaline is a naturally occurring psychoactive alkaloid that has been used as a sacrament by Indigenous populations in spiritual ritual and healing ceremonies for millennia. Despite promising early preliminary research and favorable anecdotal reports, there is limited research investigating mescaline’s psychotherapeutic potential. We administered an anonymous online questionnaire to adults (N = 452) reporting use of mescaline in naturalistic settings about mental health benefits attributed to mescaline. We assessed respondents’ self-reported improvements in depression, anxiety, post-traumatic stress disorder (PTSD), and alcohol and drug use disorders (AUD and DUD). Of the respondents reporting histories of these clinical conditions, most (68-86%) reported subjective improvement following their most memorable mescaline experience. Respondents who reported an improvement in their psychiatric conditions reported significantly higher ratings of acute psychological factors including mystical-type, psychological insight, and ego dissolution effects compared to those who did not report improvements (Cohen’s d range 0.7 – 1.5). Many respondents (35-50%) rated the mescaline experience as the single or top five most spiritually significant or meaningful experience(s) of their lives. Acute experiences of psychological insight during their mescaline experience were associated with increased odds of reporting improvement in depression, anxiety, AUD and DUD. Additional research is needed to corroborate these preliminary findings and to rigorously examine the efficacy of mescaline for psychiatric treatment in controlled, longitudinal clinical trials.

Agin-Liebes, G., Haas, T. F., Lancelotta, R., Uthaug, M. V., Ramaekers, J. G., & Davis, A. K. (2021). Naturalistic Use of Mescaline Is Associated with Self-Reported Psychiatric Improvements and Enduring Positive Life Changes. ACS pharmacology & translational science, 4(2), 543–552. https://doi.org/10.1021/acsptsci.1c00018

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Acute and Sustained Reductions in Loss of Meaning and Suicidal Ideation Following Psilocybin-Assisted Psychotherapy for Psychiatric and Existential Distress in Life-Threatening Cancer

Abstract

People with advanced cancer are at heightened risk of desire for hastened death (DHD), suicidal ideation (SI), and completed suicide. Loss of Meaning (LoM), a component of demoralization, can be elevated by a cancer diagnosis and predicts DHD and SI in this population. We completed a randomized controlled trial in which psilocybin-assisted psychotherapy (PAP) produced rapid and sustained improvements in depression, demoralization, and hopelessness in people with cancer. Converging epidemiologic and clinical trial findings suggests a potential antisuicidal effect of this treatment. To probe our hypothesis that PAP relieves SI through its beneficial impacts on depression and demoralization (LoM in particular), we performed secondary analyses assessing within- and between-group differences with regard to LoM and an SI composite score. Among participants with elevated SI at baseline, PAP was associated with within-group reductions in SI that were apparent as early as 8 h and persisted for 6.5 months postdosing. PAP also produced large reductions in LoM from baseline that were apparent 2 weeks after treatment and remained significant and robust at the 6.5 month and 3.2 and 4.5 year follow-ups. Exploratory analyses support our hypothesis and suggest that PAP may be an effective antisuicidal intervention following a cancer diagnosis due to its positive impact on hopelessness and demoralization and its effects on meaning-making in particular. These preliminary results implicate psilocybin treatment as a potentially effective alternative to existing antidepressant medications in patients with cancer that are also suicidal, and warrant further investigation in participants with elevated levels of depression and suicidality.

Ross, S., Agin-Liebes, G., Lo, S., Zeifman, R. J., Ghazal, L., Benville, J., Franco Corso, S., Bjerre Real, C., Guss, J., Bossis, A., & Mennenga, S. E. (2021). Acute and Sustained Reductions in Loss of Meaning and Suicidal Ideation Following Psilocybin-Assisted Psychotherapy for Psychiatric and Existential Distress in Life-Threatening Cancer. ACS pharmacology & translational science, 4(2), 553–562. https://doi.org/10.1021/acsptsci.1c00020

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On the Relationship between Classic Psychedelics and Suicidality: A Systematic Review

Abstract

Use of classic psychedelics (e.g., psilocybin, ayahuasca, and lysergic acid diethylamide) is increasing, and psychedelic therapy is receiving growing attention as a novel mental health intervention. Suicidality remains a potential safety concern associated with classic psychedelics and is, concurrently, a mental health concern that psychedelic therapy may show promise in targeting. Accordingly, further understanding of the relationship between classic psychedelics and suicidality is needed. Therefore, we conducted a systematic review of the relationship between classic psychedelics (both non-clinical psychedelic use and psychedelic therapy) and suicidality. We identified a total of 64 articles, including 41 articles on the association between non-clinical classic psychedelic use and suicidality and 23 articles on the effects of psychedelic therapy on suicidality. Findings on the association between lifetime classic psychedelic use and suicidality were mixed, with studies finding positive, negative, and no significant association. A small number of reports of suicide and decreased suicidality following non-clinical classic psychedelic use were identified. Several cases of suicide in early psychedelic therapy were identified; however, it was unclear whether this was due to psychedelic therapy itself. In recent psychedelic therapy clinical trials, we found no reports of increased suicidality and preliminary evidence for acute and sustained decreases in suicidality following treatment. We identify some remaining questions and provide suggestions for future research on the association between classic psychedelics and suicidality.

Zeifman, R. J., Singhal, N., Breslow, L., & Weissman, C. R. (2021). On the Relationship between Classic Psychedelics and Suicidality: A Systematic Review. ACS pharmacology & translational science, 4(2), 436–451. https://doi.org/10.1021/acsptsci.1c00024

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Clinical and biological predictors of psychedelic response in the treatment of psychiatric and addictive disorders: A systematic review

Abstract

Background: The use of psychedelic treatments has shown very promising results in some psychiatric and addictive disorders, but not all patients achieved a response.

Aim: The aim of this review is to explore the clinical and biological factors which could predict the response to psychedelics in psychiatric and addictive disorders.

Methods: A systematic research was performed on MEDLINE, PsycInfo, Web of science, and Scopus databases from January 1990 to May 2020. All studies investigating the predictive factors of response to psychedelics regardless of psychiatric or addictive disorders, were included.

Results: Twenty studies investigating addictive disorder, treatment-resistant depression, obsessive-compulsive disorder and depressive and anxiety symptoms in patients with life-threatening cancer were included in this review. We found that, in all indications, the main predictive factor of response to psychedelics is the intensity of the acute psychedelic experience. Indeed, we found this factor for alcohol and tobacco use disorders, treatment-resistant depression, and anxiety and depressive symptoms in patients with life-threatening cancer, but not for obsessive-compulsive disorder.

Conclusion: The intensity of the acute psychedelic experience was the main predicting factor of response. The action mechanism of this experience was not clear, but some hypotheses could be made, such as a modulation of serotoninergic system by 5-HT2A receptors agonism, a modulation of the default mode network (DMN) with an acute modular disintegration of the DMN followed by a re-integration of this network with a normal functioning, or an anti-inflammatory effect of this treatment.

Romeo, B., Hermand, M., Pétillion, A., Karila, L., & Benyamina, A. (2021). Clinical and biological predictors of psychedelic response in the treatment of psychiatric and addictive disorders: A systematic review. Journal of psychiatric research, 137, 273–282. https://doi.org/10.1016/j.jpsychires.2021.03.002

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