Meningeal lymphatic vessel dysfunction driven by CGRP signaling causes migraine-like pain in mice.

Migraines are a type of headache that occur with other neurological symptoms, but the pathophysiology remains unclear. In this issue of the JCI, Nelson-Maney and authors used constitutive and inducible knockouts of the CGRP receptor components, elegantly demonstrating an essential function of CGRP in modulating meningeal lymphatic vessels (MLVs) in migraine. CGRP was shown to induce rearrangement of membrane-bound gap junction proteins in MLVs, resulting in a reduced CSF flux into cervical lymph nodes. The authors also provided evidence of a primary role for CGRP in modulating neuro-immune function. Finally, by showing that blocking CGRP signaling in MLVs attenuated pain behavior associated with acute migraine in rodents, the authors provided a target for pharmacological blockade of CGRP in relation to primary headache disorders.

Psychotropic Drugs Reemerging as Headache Medicines.

Scientific and public attention on the therapeutic effects of psychedelics and other psychoactive compounds in headache disorders has recently grown. The use and reported therapeutic effects of such treatments have long been reported, though formal clinical trials are only recently taking place. When considering how these substances might be further studied and eventually applied, it is important to consider the specific headache disorder, the particular drug, and the mode of use. No singular protocol will be applicable across all headache disorders and drugs. In this leading article, the nuance required to consider the value of classic psychedelics, ketamine, and cannabinoids as headache medicines is presented.

Managing Cluster Headache in Patients with Medical, Psychiatric, and Surgical Comorbidities.

PURPOSE OF REVIEW: What should a provider know about medications and other treatments in patients with cluster headache who have medical, psychiatric, and surgical comorbidities? What conversations should providers have with patients about living with and managing cluster headache? RECENT FINDINGS: While the number of treatments used in cluster headache is relatively small, numerous considerations were identified related to managing patients with comorbidities. Many of these touch on cardiac, cardiovascular, and cerebrovascular health, but full histories are needed to guide safe and effective treatment. Both older and newer treatments may be contraindicated in certain patients with cluster headache or should be considered carefully. In addition to incorporating medical, psychiatric, and surgical histories in the management plan, collaboration with other providers may be beneficial. Providers should also inquire about patient practices and discuss participation in clinical trials that might be a good fit for the individual.

Psilocybin pulse regimen reduces cluster headache attack frequency in the blinded extension phase of a randomized controlled trial.

BACKGROUND: In a recent randomized, double-blind, placebo-controlled study, we observed a nonsignificant reduction of attack frequency in cluster headache after pulse administration of psilocybin (10 mg/70 kg, 3 doses, 5 days apart each). We carried out a blinded extension phase to consider the safety and efficacy of repeating the pulse regimen. METHODS: Eligible participants returned to receive a psilocybin pulse at least 6 months after their first round of study participation. Participants kept headache diaries starting two weeks before and continuing through eight weeks after the first drug session. Ten participants completed the extension phase and all ten were included in the final analysis. RESULTS: In the three weeks after the start of the pulse, cluster attack frequency was significantly reduced from baseline (18.4 [95% confidence interval 8.4 to 28.4] to 9.8 [4.3 to 15.2] attacks/week; p = 0.013, d' = 0.97). A reduction of approximately 50% was seen regardless of individual response to psilocybin in the first round. Psilocybin was well-tolerated without any unexpected or serious adverse events. DISCUSSION: This study shows a significant reduction in cluster attack frequency in a repeat round of pulse psilocybin administration and suggests that prior response may not predict the effect of repeated treatment. To gauge the full potential of psilocybin as a viable medicine in cluster headache, future work should investigate the safety and therapeutic efficacy in larger, more representative samples over a longer time period, including repeating the treatment. CLINICAL TRIALS REGISTRATION: NCT02981173.

Adapting psychedelic medicine for headache and chronic pain disorders.

INTRODUCTION: While the majority of current research and development surrounds depression, demoralization, and substance use disorders, there are numerous reports of psychedelics having beneficial effects in other branches of medicine, including for headache disorders and chronic pain. AREAS COVERED: This perspective reviews conventional forms of treatment for headache and other chronic pain disorders and describes historical, recent, and ongoing investigations of the therapeutic effects of psychedelics in these disorders. The first two clinical trials of psilocybin in headache disorders and recent case reports of psilocybin mushroom self-administration in chronic pain patients are described. This perspective highlights several factors related to the application of psychedelics in chronic pain disorders, comparing this with the standard psychedelic-assisted psychotherapy model of treatment. EXPERT OPINION: When faced with a more constricted view of psychedelic medicine that features larger doses, underscores subjective effects in the mediation of therapeutic outcomes, and requires adjunctive psychotherapy to ensure safety and efficacy, the application of psychedelics in headache and chronic pain disorders may face challenges. It will be important to allow for flexibility and adaptation in protocols to evaluate different treatment paradigms, mechanisms of action, and the range of pharmacologic and extra-pharmacologic factors that affect psychedelic treatment outcomes.

The Potential of Psychedelics for the Treatment of Episodic Migraine.

PURPOSE OF REVIEW: This review presents the existing literature of and a framework for how psychedelic drugs might be applied as therapeutic agents in episodic migraine. RECENT FINDINGS: The therapeutic effects of psychedelics in headache disorders have been reported for decades and controlled investigations are now beginning. In the first and only clinical trial of a psychedelic drug in migraine, the single administration of low-dose psilocybin reduced weekly migraine days and pain intensity for the following 2 weeks in episodic subjects. These transitional effects, along with abortive effects in two subjects and additional findings in cluster headache, offer insight into the potential medicinal use of this and other psychedelic drugs in episodic migraine. The existing evidence supports the continued investigation of psilocybin and other psychedelics as transitional treatments in episodic migraine. Acute and preventive effects also exist, but the risks may outweigh benefits with these applications. Future research of psychedelics in episodic migraine should be tailored for this condition and not modeled after protocols used in other medical or psychiatric conditions.

Calcitonin Gene-Related Peptide Monoclonal Antibodies and Risk of SARS-CoV-2 Infection and Severe COVID-19 Outcomes Among Veterans With Migraine Disorder.

Importance: Calcitonin gene-related peptide (CGRP), a neuropeptide involved in migraine pathophysiology, is also a key neuroimmune modulator. CGRP antagonists may help mitigate the hyperinflammatory response observed in patients with COVID-19; however, findings from the literature are contradictory, and to date, no study has investigated the safety and effectiveness of CGRP antagonists against COVID-19. Objective: To evaluate the association between CGRP monoclonal antibody (mAb) treatment and risk of SARS-CoV-2 infection and sequela hospitalization, requiring supplemental oxygen, use of mechanical ventilation, or death. Design, Setting, and Participants: This retrospective cohort study analyzed the electronic health records of US veterans aged 18 to 65 years who were diagnosed with migraine disorder and were at risk of COVID-19 between January 20, 2020, and May 19, 2022. Exposure: Initiation of CGRP mAbs. Main Outcomes and Measures: The main outcome was cumulative incidence of SARS-CoV-2 infection. Odds of 30-day hospitalization, requiring supplemental oxygen, use of mechanical ventilation, or death were secondary outcomes. Results: Among 8 178 652 eligible person-trials (354 294 veterans), 9992 (mean [SD] age, 46.0 [9.5] years; 53.9% male) initiated CGRP mAbs and 8 168 660 (mean [SD] age, 46.6 [10.2] years; 65.7% male) did not initiate CGRP mAbs. Over a 28-month follow-up period, 1247 initiators (12.5%) and 780 575 noninitiators (9.6%) tested positive for SARS-CoV-2. After censoring persons who deviated from treatment, the incidence was 7.4 cases per 1000 person-months among initiators and 6.9 per 1000 person-months among noninitiators. The inverse probability-weighted observational analogs of intention-to-treat and per-protocol hazard ratios were 0.95 (95% CI, 0.89-1.01) and 0.93 (95% CI, 0.86-1.02), respectively. No significant differences in the likelihood of hospitalization (odds ratio [OR], 0.93; 95% CI, 0.62-1.41), requiring supplemental oxygen (OR, 0.77; 95% CI, 0.45-1.30), use of mechanical ventilation (OR, 0.85; 95% CI, 0.26-2.84), or death (OR, 0.67; 95% CI, 0.09-5.23) were observed between CGRP mAb initiators and noninitiators who tested positive for SARS-CoV-2. Conclusions and Relevance: In this cohort study, CGRP mAb treatment was not associated with positive SARS-CoV-2 test results or risk of severe COVID-19 outcomes, suggesting that CGRP mAbs may be used for migraine prevention during the COVID-19 pandemic. Given the few events of requiring supplemental oxygen, use of mechanical ventilation, and death, replication analysis in a larger sample of patients later in the course of disease is warranted.

Case report: Psychedelic-induced seizures captured by intracranial electrocorticography.

Classic psychedelics are currently re-emerging as therapeutic agents with unique clinical benefits; however, it is also important to recognize the adverse effects of this drug class. While the risk of seizures with this drug class is known, the literature is lacking in detail. We present a case of psychedelic mushroom-induced seizures in a person with refractory right temporal lobe epilepsy implanted with a responsive neurostimulation (RNS) system. A large increase in typical seizure frequency coincided with the ingestion of a large dose of the mushrooms. This is the first reported case of electrographically confirmed seizures associated with classic psychedelic drug use. With the surge of research and movements toward the clinical application of classic psychedelic compounds, the risk for drug-induced seizures should be considered, including factors such as a history of epilepsy and drug doses and regimens.

Understanding headache classification coding within the veterans health administration using ICD-9-CM and ICD-10-CM in fiscal years 2014-2017.

OBJECTIVES: Understand the continuity and changes in headache not-otherwise-specified (NOS), migraine, and post-traumatic headache (PTH) diagnoses after the transition from ICD-9-CM to ICD-10-CM in the Veterans Health Administration (VHA). BACKGROUND: Headache is one of the most commonly diagnosed chronic conditions managed within primary and specialty care clinics. The VHA transitioned from ICD-9-CM to ICD-10-CM on October-1-2015. The effect transitioning on coding of specific headache diagnoses is unknown. Accuracy of headache diagnosis is important since different headache types respond to different treatments. METHODS: We mapped headache diagnoses from ICD-9-CM (FY 2014/2015) onto ICD-10-CM (FY 2016/2017) and computed coding proportions two years before/after the transition in VHA. We used queries to determine the change in transition pathways. We report the odds of ICD-10-CM coding associated with ICD-9-CM controlling for provider type, and patient age, sex, and race/ethnicity. RESULTS: Only 37%, 58% and 34% of patients with ICD-9-CM coding of NOS, migraine, and PTH respectively had an ICD-10-CM headache diagnosis. Of those with an ICD-10-CM diagnosis, 73-79% had a single headache diagnosis. The odds ratios for receiving the same code in both ICD-9-CM and ICD-10-CM after adjustment for ICD-9-CM and ICD-10-CM headache comorbidities and sociodemographic factors were high (range 6-26) and statistically significant. Specifically, 75% of patients with headache NOS had received one headache diagnoses (Adjusted headache NOS-ICD-9-CM OR for headache NOS-ICD-10-CM = 6.1, 95% CI 5.89-6.32. 79% of migraineurs had one headache diagnoses, mostly migraine (Adjusted migraine-ICD-9-CM OR for migraine-ICD-10-CM = 26.43, 95% CI 25.51-27.38). The same held true for PTH (Adjusted PTH-ICD-9-CM OR for PTH-ICD-10-CM = 22.92, 95% CI: 18.97-27.68). These strong associations remained after adjustment for specialist care in ICD-10-CM follow-up period. DISCUSSION: The majority of people with ICD-9-CM headache diagnoses did not have an ICD-10-CM headache diagnosis. However, a given diagnosis in ICD-9-CM by a primary care provider (PCP) was significantly predictive of its assignment in ICD-10-CM as was seeing either a neurologist or physiatrist (compared to a generalist) for an ICD-10-CM headache diagnosis. CONCLUSION: When a veteran had a specific diagnosis in ICD-9-CM, the odds of being coded with the same diagnosis in ICD-10-CM were significantly higher. Specialist visit during the ICD-10-CM period was independently associated with all three ICD-10-CM headaches.

The therapeutic potential of psychedelics.

The development of psychedelics as medicines faces several challenges.

Exploratory investigation of a patient-informed low-dose psilocybin pulse regimen in the suppression of cluster headache: Results from a randomized, double-blind, placebo-controlled trial.

OBJECTIVE: Using a patient-informed regimen, we conducted an exploratory randomized, double-blind, placebo-controlled study to systematically investigate the effects of psilocybin in cluster headache. BACKGROUND: Sustained reductions in cluster headache burden after limited quantities of psilocybin-containing mushrooms are anecdotally reported, although to date there are no controlled studies investigating these effects. METHODS: Participants were randomized to receive psilocybin (0.143 mg/kg) or placebo (microcrystalline cellulose) in a pulse of three doses, each ~5 days apart. Participants maintained headache diaries starting 2 weeks before and continuing through 8 weeks after the first drug session. A total of 16 participants were randomized to receive experimental drug and 14 were included in the final analysis. RESULTS: In the 3 weeks after the start of the pulse regimen, the change in cluster attack frequency was 0.03 (95% confidence interval [CI] -2.6 to 2.6) attacks/week with placebo (baseline 8.9 [95% CI 3.8 to 14.0]) and -3.2 (95% CI -8.3 to 1.9) attacks/week with psilocybin (baseline 9.6 [95% CI 5.6 to 13.6]; p = 0.251). Group difference in change from baseline had a moderate effect size (d = 0.69). The effect size was small in episodic participants (d = 0.35) but large in chronic participants (d = 1.25), which remained over the entire 8-week period measured (d = 0.81). Changes in cluster attack frequency were not correlated with the intensity of acute psychotropic effects during psilocybin administration. Psilocybin was well-tolerated without any unexpected or serious adverse events. CONCLUSIONS: Findings from this initial, exploratory study provide valuable information for the development of larger, more definitive studies. Efficacy outcomes were negative, owing in part to the small number of participants. The separation of acute psychotropic effects and lasting therapeutic effects underscores the need for further investigation into the mechanism(s) of action of psilocybin in headache disorders.

Characteristics and Gender Differences of Headache in the Veterans Health Administration: A National Cohort Study, Fiscal Year 2008-2019.

BACKGROUND AND OBJECTIVES: - To determine gender differences in headache types diagnosed, sociodemographic characteristics, military campaign and exposures, and healthcare utilization among United States (U.S.) Veterans in the Veterans Health Administration (VHA). METHODS: - This study employed a retrospective cohort design to examine VHA Electronic Health Record (EHR) data. This cohort includes Veterans who had at least one visit for any headache between fiscal years 2008 and 2019. Headache diagnoses were classified into eight categories using International Classification of Disease, Clinical Modification codes. Demographics, military-related exposures, comorbidities, and type of provider(s) consulted were extracted from the EHR, and compared by gender. Age-adjusted incidence and prevalence rates of medically diagnosed headache disorders were calculated separately for each type of headache. RESULTS: - Of the 1,524,960 Veterans with headache diagnoses included in the cohort, 82.8% were men. Compared with women, men were more often white (70.4% vs 56.7%), older (52.0±16.8 vs 41.9±13.0 years), with higher rates of traumatic brain injury (2.9% vs 1.1%) and post-traumatic stress disorder (23.7% vs 21.7%), and lower rates of military sexual trauma (3.2% vs 33.7%; p<0.001 for all). Age adjusted incidence rate of headache of any type was higher among women. Migraine and trigeminal autonomic cephalalgias rates were most stable over time. Men were more likely than women to be diagnosed with headache not-otherwise-specified (77.4% vs 67.7%) and have higher incidence rates of headaches related to trauma (3.4% vs 1.9% [post-traumatic]; 5.5% vs 5.1% [post-whiplash]; p <0.001 for all). Men also had fewer headache types diagnosed (mean ± standard deviation; 1.3 ± 0.6 vs 1.5 ± 0.7), had fewer encounters for headache/year (0.8 ± 1.2 vs 1.2 ± 1.6) and fewer visits to headache specialists (20.8% vs 27.4% p <0.001 for all), compared to women. Emergency Department utilization for headache care was high for both genders and higher for women compared to men (20.3% vs 22.9%; p<0.001). DISCUSSION: - Among Veterans with headache diagnoses, important gender differences exist for men and women Veterans receiving headache care within VHA regarding sociodemographic characteristics, headache diagnoses, military exposure, and headache healthcare utilization. The findings have potential implications for providers and the healthcare system caring for Veterans living with headache.

Self-Reported Efficacy of Treatments in Cluster Headache: a Systematic Review of Survey Studies.

PURPOSE OF REVIEW: The use and efficacy of various substances in the treatment of CH have been studied in several retrospective surveys. The aim of the study is to systematically review published survey studies to evaluate the reported efficacies of both established and unconventional substances in abortive and prophylactic treatment of both episodic and chronic CH, specifically assessing the consistency of the results. RECENT FINDINGS: No systematic review have been conducted of these studies previously. A systematic literature search with a set of search terms was conducted on PubMed. Retrospective surveys that quantified the self-reported efficacy of two or more CH treatments, published in English during 2000-2020, were included. Several key characteristics and results of the studies were extracted. A total of 994 articles were identified of which 9 were found to be eligible based on the selection criteria. In total, 5419 respondents were included. Oxygen and subcutaneous triptan injections were most reported as effective abortive treatments, while psilocybin and lysergic acid diethylamide were most commonly reported as effective prophylactic treatments. The reported efficacy of most substances was consistent across different studies, and there were marked differences in the reported efficacies of different substances. The reported order of efficacy is generally in agreement with clinical studies. The findings suggest that retrospective surveys can be used to obtain supporting information on the effects of various substances used in the treatment of CH and to form hypotheses about novel treatment methods. The consistently reported efficacy of psilocybin and LSD in prophylactic treatment indicates need for clinical studies.

Psychedelics as preventive treatment in headache and chronic pain disorders.

The effects of psychedelic drugs in headache and chronic pain disorders have been reported for several decades, and now controlled studies are emerging. The existing evidence supports a lasting therapeutic benefit after limited dosing, a unique feature of the drug class that distinguishes it from conventional treatment. This commentary summarizes these reports of preventive effects of psychedelic drugs in headache and chronic pain disorders. The recently published controlled trial of psilocybin in migraine is reviewed, including its limitations. Several neurobiological targets of psychedelics that are related to headache and chronic pain are highlighted, though a clear separation of acute and lasting effects is key in uncovering the unique clinical effects of this drug class. Considerable investigation is required before the effects, safety, and mechanism of action of psychedelics in headache and chronic pain disorders can be known.

Psychedelics in the Treatment of Headache and Chronic Pain Disorders.

The therapeutic potential of psychedelics in headache and chronic pain disorders is documented over decades of anecdotal and early investigational reports, which have paved the way for the first controlled studies of psilocybin and lysergic acid diethylamide (LSD) in these disorders. The reported lasting clinical effects after limited dosing with psychedelics present a novel means for disease management, but considerable further study will be required to address disease-specific treatments, uncover mechanism(s) of action, and verify safety. In this chapter, these topics are reviewed with particular attention to the neurobiological systems that offer potential sources of psychedelics' unique clinical effects in headache and pain.

Recent advances in the diagnosis and management of cluster headache.

Cluster headache, a primary headache disorder, consists of short (15-180 minutes), frequent (up to eight a day), unilateral attacks of facial pain with associated ipsilateral autonomic features and restlessness. The attacks are suspected to be one of the most painful human experiences, and the disorder is associated with a high rate of suicidal ideation. Proper diagnosis is key, as some of the most effective treatments, such as high flow oxygen gas, are rarely used in other headache disorders. Yet diagnostic delay is typically years for this disorder, as it is often confused with migraine and trigeminal neuralgia, and secondary causes may be overlooked. This review covers the clinical, pathophysiologic, and therapeutic features of cluster headache. Recent updates in diagnosis include the redefinition of chronic cluster headache (remission periods lasting less than three months instead of the previous one month), and recent advances in management include new treatments for episodic cluster headache (galcanezumab and non-invasive vagus nerve stimulation).

Cluster Headache: Clinical Characteristics and Opportunities to Enhance Quality of Life.

PURPOSE OF REVIEW: Cluster headache is a highly disabling primary headache disorder characterized by severe pain and autonomic features. We present the existing body of literature on psychological factors associated with cluster headache and recommendations to address gaps in current clinical care with regards to psychological treatments for cluster headache. RECENT FINDINGS: People with cluster headache often endorse depressive symptoms, are more likely than the general population to report suicidal ideation and behaviors, and experience significantly decreased quality of life. Psychological treatments such as Acceptance and Commitment Therapy may be particularly valuable for patients with cluster headache given that they are transdiagnostic in nature and can therefore simultaneously address the disease burden and common psychiatric comorbidities that present. Greater understanding of the debilitating nature of cluster headache and behavioral interventions that seek to reduce the burden of the disease and improve the quality of life of people with cluster headache is paramount.

Demoralization predicts suicidality in patients with cluster headache.

OBJECTIVE: To determine the frequency of suicidal ideation and assess suicide risk in cluster headache (CH) patients compared to matched controls without CH in this observational case-control study. BACKGROUND: CH is characterized by recurrent intolerable attacks of unilateral retro-orbital pain, which can cause disability, depression, and desperation. CH has been linked to suicide since its early descriptions by B.T. Horton; however, there is relatively little empiric data showing the association between suicidality and CH, especially in the context of other psychological phenomena, such as depression and demoralization. METHODS: CH and control participants were recruited through community and CH patient group advertisements. CH diagnosis was confirmed using the International Classification of Headache Disorders, 3rd edition diagnostic criteria for CH. Lifetime suicidal ideation and suicide risk were assessed using the Suicidal Behavior Questionnaire-revised and the Columbia Suicide Severity Rating Scale. The Brief Lifetime Depression Scale evaluated lifetime depression. Demoralization was assessed using the Diagnostic Criteria for use in Psychosomatic Research - Demoralization and the Kissane Demoralization Scale. Forward stepwise logistic regression determined the odds of suicidal ideation. RESULTS: One hundred CH and 135 control participants were comparable for age, sex, race, income, and marital status. Significantly more CH than control participants had lifetime active suicidal ideation (47.0% vs. 26.7%; p = 0.001), high suicide risk (38.0% vs. 18.5%; p = 0.0009), lifetime depression history (67.0%% vs. 32.6%; p < 0.00001), and demoralization (28.0% vs. 15.6%; p = 0.02). The odds of lifetime suicidal ideation were higher in those with CH (odds [95% confidence interval]; 2.04 [1.08,3.85]), even after accounting for depression and demoralization. In CH, suicidal ideation was associated with demoralization (6.66 [1.56,28.49]) but not depression (1.89 [0.66,5.46]). CONCLUSIONS: Lifetime suicidal ideation and high suicide risk are prevalent in CH sufferers, and its likelihood is dependent on the presence of demoralization.

"You will eat shoe polish if you think it would help"-Familiar and lesser-known themes identified from mixed-methods analysis of a cluster headache survey.

OBJECTIVE: To characterize patient-reported ideas and concerns about cluster headache, treatment options, and management strategies. BACKGROUND: Cluster headache patients experience severe pain and often suffer additional consequences from their disease. Patients have identified methods to cope with and combat cluster headache that are not widely known. METHODS: Secondary analysis was performed using deidentified data from the online Clusterbusters Medication Use survey, wherein 10 questions allowed for freely written comments. Using mixed-methods techniques, neurologists with expertise in headache medicine identified themes from these comments. Subgroup analysis sought to identify variables associated with specific themes. RESULTS: Among 2274 free-text responses from 493 adult participants, 23 themes were identified. Themes commonly discussed in the literature included such topics as "nothing worked" (24.7%, 122/493), "side effects" (12.8%, 63/493), and difficulties with "access/cost" (2.4%, 12/493). Less widely recognized themes included the use of "illicit substances" (35.5%, 175/493) and "vitamins/supplements" (12.2%, 60/493) in disease management. Lesser-known themes included "coffee" (5.3%, 26/493) and "exercise/physical activity" (4.7%, 23/493). Using strict significance criteria, no subgroup was associated with any theme. Several poignant quotes highlighted patient thoughts and experiences. CONCLUSIONS: This mixed-methods analysis identified challenges endured by cluster headache patients, as well as a variety of patient-directed disease management approaches. The volunteered information spotlights pharmacological, physiological, and psychological aspects of cluster headache that warrant further exploratory and interventional investigation.

Exploratory Controlled Study of the Migraine-Suppressing Effects of Psilocybin.

While anecdotal evidence suggests that select 5-hydroxytryptamine 2A (5-HT2A) receptor ligands, including psilocybin, may have long-lasting therapeutic effects after limited dosing in headache disorders, controlled investigations are lacking. In an exploratory double-blind, placebo-controlled, cross-over study, adults with migraine received oral placebo and psilocybin (0.143 mg/kg) in 2 test sessions spaced 2 weeks apart. Subjects maintained headache diaries starting 2 weeks before the first session until 2 weeks after the second session. Physiological and psychological drug effects were monitored during sessions and several follow-up contacts with subjects were carried out to assure safety of study procedures. Ten subjects were included in the final analysis. Over the 2-week period measured after single administration, the reduction in weekly migraine days from baseline was significantly greater after psilocybin (mean, - 1.65 (95% CI: - 2.53 to - 0.77) days/week) than after placebo (- 0.15 (- 1.13 to 0.83) days/week; p = 0.003, t(9) = 4.11). Changes in migraine frequency in the 2 weeks after psilocybin were not correlated with the intensity of acute psychotropic effects during drug administration. Psilocybin was well-tolerated; there were no unexpected or serious adverse events or withdrawals due to adverse events. This exploratory study suggests there is an enduring therapeutic effect in migraine headache after a single administration of psilocybin. The separation of acute psychotropic effects and lasting therapeutic effects is an important finding, urging further investigation into the mechanism underlying the clinical effects of select 5-HT2A receptor compounds in migraine, as well as other neuropsychiatric conditions. Clinicaltrials.gov : NCT03341689.