Views on Using Psychoactive Substances to Self-Manage Functional Neurological Disorder: Online Patient Survey Results

Functional neurological disorder (FND) encompasses motor and/or sensory symptoms—such as seizures, movement disorders, weakness, and sensory abnormalities—that are not explained by other neurological diseases but instead reflect altered access to voluntary movement control and/or normal sensory perception. Disability in FND can be severe and long-standing. Psychological and physical therapies are the principal evidence-based treatments, yet high-quality evidence is limited, access is often poor, and many patients continue to experience persistent or worsening symptoms despite best-practice care. Pharmacological options are similarly sparse, although specific cases (for example, therapeutic sedation for functional dystonia) suggest some potential utility. Because effective and accessible treatments are lacking, some people with FND may seek alternative self-management strategies, including legal and illicit psychoactive substances. Earlier research and case reports suggest such substances are used in other neuropsychiatric conditions and that there is renewed clinical interest in agents such as ketamine, MDMA, cannabis compounds, and classical psychedelics. Butler and colleagues therefore conducted a large online survey to characterise the prevalence and subjective effectiveness of legal and illicit psychoactive substance use for FND self-management and to assess patient views on medically supervised psychedelic therapy as a potential novel treatment avenue.

This cross-sectional, observational study used an online questionnaire open for approximately one month (September–October 2019). Respondents were recruited internationally via social media (Twitter, Facebook) and patient support groups (for example, FND Hope, FND Action). Inclusion required self-report of a formal FND diagnosis from a doctor; diagnoses were not clinically verified. The survey comprised plain-English items developed with input from the charity FND Hope and included multiple-choice checkboxes, visual analogue scales (VAS), and free-text fields. Key topics were lifetime use of legal substances (for example, caffeine, alcohol, cannabidiol/CBD, nicotine) and illicit substances (for example, cannabis, ketamine, psychedelics), rating of subjective effectiveness on 0–100 VAS anchors, complications or sequelae experienced after use, and willingness to try medically supervised psychedelic therapy if shown to be safe and effective (also rated on a 0–100 VAS). Mutually incompatible multiple responses were removed when applicable. Analyses were descriptive, using IBM SPSS Statistics v26 for frequencies, proportions, measures of central tendency and dispersion, and chi-square tests for between-group frequency comparisons. Kernel density estimates were constructed using custom scripts in RStudio. The study received ethical approval from King's College London Research Ethics Committee and conformed to the Declaration of Helsinki.

Respondent characteristics: A total of 1,162 people from 16 countries completed the survey; most respondents resided in the United Kingdom. After excluding those who did not report a formal diagnosis, 1,048 respondents were included for analysis. The sample was 86% female (N=903), with a mean age of 42.5 years (SD 12.7). Mean duration from first FND symptom to survey was 8.7 years (SD 9.4) and mean time from first symptom to diagnosis was 5.4 years (SD 8.6). Response rates varied slightly across items. Legal psychoactive substances: Of 980 respondents who answered the relevant item, 451 (46%) reported having tried legal substances to manage their FND symptoms. Median VAS effectiveness scores (0–100) were reported as cannabidiol (CBD) 52.0 (N=196), caffeine 34.0 (N=87), alcohol 32.5 (N=68), tobacco 22.0 (N=51) and nicotine 18.0 (N=30). For CBD, 22% of respondents rated it as extremely effective (above 75/100). Use of caffeine was more commonly reported among those currently taking prescription medication, while CBD use was unrelated to medication status. Illicit and non-prescribed medicines: Eighty-nine respondents (79/979, 8%) indicated use of prescription medication obtained without a prescription, and 329/978 (34%) had considered illicit substances for symptom relief but had not used them because of illegality or safety concerns. Eight respondents reported being legally prescribed medical cannabis for FND. A total of 151/978 (15%) reported having used illicit substances to self-manage symptoms; some reported multiple substances. Most who used illicit substances reported either no or minimal physical (90%) and psychological (95%) sequelae, although a few respondents reported severe physical (N=5) or psychological (N=3) complications after using cannabis, cocaine, or MDMA. Effectiveness of illicit substances: Median VAS effectiveness scores (0–100) reported for substances with adequate respondent numbers were: cannabis 73.0 (N=142), ketamine 72.0 (N=7), amphetamines 69.0 (N=9), cocaine 67.0 (N=13), MDMA 61.0 (N=7), and psychedelics 54.0 (N=10). The authors caution that sample sizes were small for most illicit substances and there was substantial interindividual variation. Willingness to consider psychedelic therapy: Respondents' willingness to try medically supervised psychedelic therapy (if shown to be safe and effective) was split: 46% were classified as willing (VAS >67), 35% unwilling (VAS <34), and 19% ambivalent (VAS 34–67). The distribution was skewed toward extreme responses, with many indicating they were completely willing.

Butler and colleagues interpret the findings as indicating that a substantial minority of people with FND attempt to self-manage symptoms using legal and illicit psychoactive substances. Legal substances were generally rated as having modest benefit, with CBD receiving the highest median effectiveness among legal agents. Cannabis was the most frequently reported illicit substance and received a greater-than-moderate median effectiveness rating, alongside a generally favourable self-reported side-effect profile among users. The authors emphasise limitations in drawing causal inferences from these self-report data: the survey was not designed to determine whether substances affected core FND features versus associated symptoms (for example, sleep or fatigue), and the placebo/expectation effect may be a prominent contributor to perceived benefit given known placebo responsivity in FND and overlapping neural circuitry. Safety concerns are noted: although most users reported minimal sequelae, a small number of respondents reported severe adverse physical or psychological effects after use of cannabis, cocaine, or MDMA. Illicit supply, adulterants, and lack of clinical supervision complicate interpretation of harms reported outside medical settings. Regarding potential therapeutic research priorities, the authors discuss candidate agents reported in the survey and in the literature: cannabis compounds (particularly where pain is comorbid), amphetamines for fatigue-dominant presentations, MDMA as an adjunct to psychotherapy in trauma-related cases, ketamine given its dissociative/antidepressant profile, and classical psychedelics because of mechanistic hypotheses (for example, serotonin 2A receptor effects on self-representation networks). They note small historic and case-report data in FND and reassure that early-phase safety data for psychedelics in other disorders are encouraging. However, they stress that most illicit-substance findings in this survey rest on small Ns and substantial heterogeneity and therefore should be interpreted with extreme caution. Strengths and limitations are reiterated: the large international sample (over 1,000 respondents) increases the breadth of perspectives captured, but selection bias toward English-speaking, internet-active participants and reliance on self-reported diagnosis limit generalisability. The survey did not capture whether substances worsened symptoms, pain comorbidity, medication intolerances, or objective verification of outcomes. Sensitive questions about illicit use may have led to underreporting. The authors frame the study as descriptive rather than evidence of efficacy.

The investigators conclude that many people with FND attempt to manage symptoms with both legal and illicit psychoactive substances and that some substances reported modest or greater subjective benefit. Given precedent from clinical trials of substances such as ketamine, MDMA, and psilocybin in other neuropsychiatric disorders, together with tolerability signals in this survey and reasonable patient acceptability for psychedelic therapy, the authors suggest that FND could be considered as a target for future clinical research. Specifically, they propose that a pilot trial of psilocybin for FND may be a justifiable option for further investigation.