Johannes G Ramaekers

Johannes G Ramaekers
Maastricht University | UM · Department of Neuropsychology and Psychopharmacology

Prof dr

About

328
Publications
89,348
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
9,688
Citations

Publications

Publications (328)
Article
Full-text available
Although several studies and reports have shown the potential analgesic use of serotonergic psychedelics in cancer pain, phantom limb pain and cluster headache, evidence supporting their use for chronic pain is still limited. The past years have seen a considerable renewal of interest toward the therapeutic use of these compounds for mood disorders...
Article
Full-text available
Anxiety disorders are the most common type of psychiatric disorders among Western countries. Evidence-based treatment modalities including pharmacological and cognitive-behavioral therapy result in deficient treatment responses. Historical and recent research suggests psychedelic drugs may be efficacious in alleviating anxiety-related symptoms amon...
Article
Full-text available
Recent studies have recognized the importance of non-pharmacological factors such as setting to induce or promote mystical experiences or challenging experiences among ayahuasca users. This study aimed to evaluate the association between the setting in which ayahuasca is consumed and the intensity of mystical and challenging experiences considering...
Article
Full-text available
Modern clinical research on psychedelics is generating interesting outcomes in a wide array of clinical conditions when psychedelic-assisted psychotherapy is delivered to appropriately screened participants and in controlled settings. Still, a number of patients relapse or are less responsive to such treatments. Individual and contextual factors (i...
Article
Full-text available
Rationale Studies have suggested mental health improvements following the use of the psychotropic plant concoction ayahuasca in non-clinical and clinical samples. Objectives The present observational study assessed depressive symptomatology in 20 clinically depressed patients (symptom score > 13 on the Beck’s Depression Inventory) before attendanc...
Article
Full-text available
Background Novel psychedelics (NPs) are an expanding set of compounds, presenting new challenges for drug policy and opportunities for clinical research. Unlike their classical derivatives, little is known regarding their use profiles or their subjective effects. Aims The purpose of this study was to compile usage patterns and adverse event rates...
Article
Objective: To evaluate the impact of solriamfetol, a dopamine and norepinephrine reuptake inhibitor, on on-the-road driving in participants with excessive daytime sleepiness (EDS) associated with obstructive sleep apnoea (OSA). Methods: Eligible participants were aged 21-75 years with OSA and EDS (Maintenance of Wakefulness Test mean sleep laten...
Article
Full-text available
Background Synthetic cannabinoids (SCs) are the largest class of novel psychoactive substances (NPS) and are associated with an increased risk of overdosing and adverse events such as psychosis. JWH-018 is one of the earliest SCs and still widely available in large parts of the world. Controlled studies to assess the safety and behavioural profiles...
Article
Clinical research into serotonergic psychedelics is expanding rapidly, showing promising efficacy across myriad disorders. Resting-state functional magnetic resonance imaging (rs-fMRI) is a commonly used strategy to identify psychedelic-induced changes in neural pathways in clinical and healthy populations. Here we, a large group of psychedelic ima...
Article
Full-text available
Currently, the assessment of the neurobehavioral consequences of repeated cannabis use is restricted to studies in which brain function of chronic cannabis users is compared to that of non-cannabis using controls. The assumption of such studies is that changes in brain function of chronic users are caused by repeated and prolonged exposure to acute...
Article
Full-text available
There has been a renewed interest in the potential use of psychedelics for the treatment of psychiatric conditions. Nevertheless, little is known about the mechanism of action and molecular pathways influenced by ayahuasca use in humans. Therefore, for the first time, our study aims to investigate the human metabolomics signature after consumption...
Preprint
Anxiety disorders are the most common type of psychiatric disorders among Western countries. Evidence-based treatment modalities including pharmacological and cognitive-behavioral therapy result in relatively low response rates (average range: 51 - 58%). Historical and recent research suggests psychedelic drugs may be efficacious in alleviating anx...
Article
Full-text available
Resting state fMRI has been employed to identify alterations in functional connectivity within or between brain regions following acute and chronic exposure to Δ9-tetrahydrocannabinol (THC), the psychoactive component in cannabis. Most studies focused a priori on a limited number of local brain areas or circuits, without considering the impact of c...
Article
The entactogen 3,4-Methylenedioxymethamphetamine (MDMA) is increasingly being recognized for its therapeutic potential but is also widespread in nightlife settings where it may co-occur with crime. Since previous research detected impaired verbal memory during acute MDMA intoxication, understanding the drug's ramifications in an applied legal conte...
Article
Background: Controversy surrounds psychedelics and their potential to boost creativity. To date, psychedelic studies lack a uniform conceptualization of creativity and methodologically rigorous designs. Aims: This study aimed at addressing previous issues by examining the effects of lysergic acid diethylamide (LSD) on creativity using multimodal...
Article
Full-text available
5‐methoxy‐N,N‐dimethyltryptamine (5‐MeO‐DMT) is a naturally occurring tryptamine that primarily acts as an agonist at the 5‐HT1A and 5‐HT2A receptors, whereby affinity for the 5‐HT1A subtype is highest. Subjective effects following 5‐MeO‐DMT administration include distortions in auditory and time perception, amplification of emotional states and fe...
Article
The use of alcohol among road users injured in road traffic crashes and admitted to three major hospitals in Cameroon was studied. Alcohol use was measured using breathalyzers, and data on age, gender, education level, religion, type of road user, time of the crash, crash characteristics, and injury severity were recorded using a questionnaire. Of...
Article
Full-text available
Some evidence suggests that males and females may differ in their responses to acute cannabis effects, including subjective drug effects and behavioural effects, and cannabinoid pharmacokinetics. This is significant given current changes to cannabis-related policies and, in consequence, increased cannabis accessibility. The present study combines d...
Article
Full-text available
5-Methoxy-N,N-Dimethyltryptamine (5-MeO-DMT) is a tryptamine with ultra-rapid onset and short duration of psychedelic effects. Prospective studies for other tryptamines have suggested beneficial effects on mental health outcomes. In preparation for a study in patients with depression, the present study GH001-HV-101 aimed to assess the impact of fou...
Article
Full-text available
Background: Naturalistic and placebo-controlled studies have suggested that ayahuasca, a traditional Amazonian beverage, could be helpful in the treatment of psychopathologies like depression and anxiety disorders by changing otherwise disturbed cognitive and emotional processes. To better understand its full therapeutic potential, one way is to st...
Article
Full-text available
Fatigue poses an important safety risk to civil and military aviation. In addition to decreasing performance in-flight (chronic) fatigue has negative long-term health effects. Possible causes of fatigue include sleep loss, extended time awake, circadian phase irregularities and work load. Despite regulations limiting flight time and enabling optima...
Article
Full-text available
Background and aims There is a growing body of evidence suggesting that the psychedelic plant tea, ayahuasca, holds therapeutic potential. Uthaug et al. (2018) demonstrated that a single dose of ayahuasca improved mental health sub-acutely and 4-weeks post-ceremony in healthy participants. The present study aimed to replicate and extend these findi...
Article
Full-text available
Ayahuasca is a plant concoction containing N,N-dimethyltryptamine (DMT) and certain β-carboline alkaloids from South America. Previous research in naturalistic settings has suggested that ingestion of ayahuasca can improve mental health and well-being; however, these studies were not placebo controlled and did not control for the possibility of exp...
Article
Full-text available
Introduction Kratom (Mitragyna speciosa) is a tropical plant traditionally used as an ethnomedicinal remedy for several conditions in South East Asia. Despite the increased interest in its therapeutical benefits in Western countries, little scientific evidence is available to support such claims, and existing data remain limited to kratom's chronic...
Article
Full-text available
The growing interest in research on psychedelic consumption in naturalistic contexts and their possible medical and therapeutic benefits requires assessment of the relationships between the substance and the individual who consumes it (set) and its context of use (setting). This study provides a novel measurement scale for the setting of Ayahuasca...
Article
Full-text available
Objective: This study aimed to assess the prevalence of drinking and driving on roadways in urban areas and highways in Cameroon, and to determine the associations between drinking and driving and socio-demographic factors. Methods: A cross-sectional study of motor vehicle drivers was performed on Fridays, Saturdays, and Sundays between May and...
Article
Full-text available
Background: Mescaline is a naturally occurring psychoactive phenethylamine found in several cacti and historically used ceremonially by Indigenous and Latin American populations. Broader recognition of its possible therapeutic value in Western science began in the 1950s; however, knowledge of the safety profile of mescaline and the extent of its u...
Article
Acute cannabis intoxication may induce neurocognitive impairment and is a possible cause of human error, injury and psychological distress. One of the major concerns raised about increasing cannabis legalization and the therapeutic use of cannabis is that it will increase cannabis‐related harm. However, the impairing effect of cannabis during intox...
Article
Full-text available
Creativity is an essential cognitive ability linked to all areas of our everyday functioning. Thus, finding a way to enhance it is of broad interest. A large number of anecdotal reports suggest that the consumption of psychedelic drugs can enhance creative thinking; however, scientific evidence is lacking. Following a double-blind, placebo-controll...
Article
In Reply Our recent investigation¹ about the effects of CBD and THC on driving offers relevant insights for research and policy. This study confirmed previous findings from on-road and driving simulator studies² showing that THC produces modest but clinically relevant driving impairment similar to that seen in drivers with a blood alcohol concentra...
Article
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...
Preprint
Full-text available
Resting state fMRI has been employed to identify alterations in functional connectivity within or between brain regions following acute and chronic exposure to Δ9-tetrahydrocannabinol (THC), the psychoactive component in cannabis. Most studies focused a priori on a limited number of local brain areas or circuits, without considering the impact of c...
Article
Kratom (Mitragyna speciosa) is a tree native to Southeast Asia with long history of traditional medicinal use. The aim of this study was to investigate the nature of self-reported exported experiences as shared on YouTube™ videos. A total of 500 videos with 19,478,180 views and 134, 863 comments emerged from the data scrape extracted via the YouTub...
Article
Full-text available
Objective: Previous research reported cognitive and psychomotor impairments in long-term users of benzodiazepine receptor agonists (BZRAs). This article explores the role of acute intoxication and clinical complaints. Methods: Neurocognitive and on-road driving performance of 19 long-term (≥6 months) regular (≥twice weekly) BZRA users with estim...
Article
Full-text available
Introduction Excessive Daytime Sleepiness is a core symptom of narcolepsy and idiopathic hypersomnia, which impairs driving performance. Adequate treatment improves daytime alertness, but it is unclear whether driving performance completely normalizes. This study compares driving performance of patients with narcolepsy and idiopathic hypersomnia re...
Article
Full-text available
Background: Ecstasy (3,4-methylenedioxymethamphetamine (MDMA)) has a relatively low harm and low dependence liability but is scheduled on List I of the Dutch Opium Act ('hard drugs'). Concerns surrounding increasing MDMA-related criminality coupled with the possibly inappropriate scheduling of MDMA initiated a debate to revise the current Dutch ec...
Article
Background Smoking mixtures containing synthetic cannabinoids (SCs) have become very popular over the last years but pose a serious risk for public health. Limited knowledge is, however, available regarding the acute effects of SCs on cognition and psychomotor performance. Earlier we demonstrated signs of impairment in healthy volunteers after admi...
Article
Full-text available
Importance Cannabis use has been associated with increased crash risk, but the effect of cannabidiol (CBD) on driving is unclear. Objective To determine the driving impairment caused by vaporized cannabis containing Δ⁹-tetrahydrocannabinol (THC) and CBD. Design, Setting, and Participants A double-blind, within-participants, randomized clinical tr...
Article
The assessment of cannabinoid concentrations in blood with regard to psychoactive effects is particularly important in traffic offences. A direct correlation is not established, but Huestis et al. have established calculation models for estimating the time of consumption (J Anal Toxicol 16, 283 ff). However, in view of recent studies on abstinence...
Preprint
Background: MDMA (ecstasy, 3,4-methylenedioxymethamphetamine) has a relatively low harm and low dependence liability but is scheduled on List I of the Dutch Opium Act together (“hard drugs”). Concerns surrounding increasing MDMA-related criminality coupled with the possibly inappropriate scheduling of MDMA initiated a debate to revise the current D...
Article
Over the last two decades, misuse of 4-fluoroamphetamine (4-FA) became an emerging issue in many European countries. Stimulating effects last for 4-6 hours and can impact psychomotor performance. The metabolism of amphetamine-type stimulants is stereoselective and quantification of (R)- and (S)-enantiomers has been suggested for assessing time of u...
Article
Full-text available
Objective: To assess driving performance and neurocognitive skills of long-term users of sedating antidepressants, in comparison to healthy controls. Methods: Thirty-eight long-term (>6 months) users of amitriptyline (n = 13) and mirtazapine (n = 25) were compared to 65 healthy controls. Driving performance was assessed using a 1-h standardised...
Article
Full-text available
There is a popular interest in microdosing with psychedelics such as LSD. This practice of using one-tenth of a full psychedelic dose according to a specific dosing schedule, anecdotally enhances mood and performance. Nonetheless, controlled research on the efficacy of microdosing is scarce. The main objective of the present dose-finding study was...
Article
Full-text available
"Microdoses" of lysergic acid diethylamide (LSD) are used recreationally to enhance mood and cognition. Increasing interest has also been seen in developing LSD into a medication. Therefore, we performed a pharmacokinetic-pharmacodynamic study using very low doses of LSD. Single doses of LSD base (5, 10, and 20 µg) and placebo were administered in...
Article
Introduction Ecstasy (MDMA) is a popular recreational drug, but its illegal production and trade in the Netherlands have developed into a serious public order and ecological problem which endanger and question the harm reduction approach of the Dutch ecstasy policy. Methods The market characteristics, adverse health effects, risk profile, and link...
Article
Despite preclinical evidence for psychedelic-induced neuroplasticity, confirmation in humans is grossly lacking. Given the increased interest in using low doses of psychedelics for psychiatric indications, and the importance of neuroplasticity in the therapeutic response, this placebo-controlled within-subject study investigated the effect of singl...
Article
Full-text available
Background Lysergic acid diethylamide (LSD) is an ergot alkaloid derivative with psychedelic properties that has been implicated in the management of persistent pain. Clinical studies in the 1960s and 1970s have demonstrated profound analgesic effects of full doses of LSD in terminally ill patients, but this line of research evaporated after LSD wa...
Article
Full-text available
Objective The influence of psychoactive substances on driving performance and traffic safety has been extensively studied. Research on the influence of alcohol at the control level of behaviour (i.e. automated processes) has been well established and has shown that the ability to operate a vehicle decreases with rising alcohol levels. However, resu...
Article
Introduction Excessive daytime sleepiness (EDS) in patients with obstructive sleep apnea (OSA) is associated with an increased risk of driving accidents. Solriamfetol, a dopamine/norepinephrine reuptake inhibitor, is approved in the US (Sunosi®) for EDS associated with OSA (37.5-150 mg/day). This study evaluated solriamfetol’s effects on on-road dr...
Article
Introduction Patients with narcolepsy have an increased risk of automobile accidents. Solriamfetol, a dopamine/norepinephrine reuptake inhibitor, is approved in the US (Sunosi®) for adults with excessive daytime sleepiness (EDS) associated with narcolepsy (75-150 mg/day). This study evaluated the effects of solriamfetol on on-road driving performan...
Article
Full-text available
Aims 22q11.2 deletion syndrome (22q11.2DS) is associated with impaired cognitive functioning. Glutamatergic pathways have been linked with cognition and are hypothesized to be disrupted in 22q11.2DS patients, possibly ‘shifting’ the excitatory (glutamate)/inhibitory (GABA) balance. Hence, the glutamate/GABA balance may constitute a target for pharm...
Article
Full-text available
There is growing interest in the therapeutic utility of psychedelic substances, like psilocybin, for disorders characterized by distortions of the self-experience, like depression. Accumulating preclinical evidence emphasizes the role of the glutamate system in the acute action of the drug on brain and behavior; however this has never been tested i...
Article
Introduction Cerumen was found to be a promising alternative specimen for the detection of drugs. In a pilot study, drugs of abuse were identified at a high detection rate and a longer detection window for abused drugs than in urine. In the present study, cerumen from subjects was analyzed after controlled oral ingestion of the designer stimulant 4...
Article
Full-text available
Background: Previous research suggests a therapeutic potential of 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT). However, online anecdotal reports have described a phenomenon following cessation of the acute effects of 5-MeO-DMT use which has been termed reactivation (i.e., re-experiencing [“flashback”]). To date, no research has investigated whethe...
Article
The rapid proliferation of new synthetic cannabinoid receptor agonists (SCRAs) has initiated considerable interest in the development of so-called “untargeted” screening strategies. One of these new screening technologies involves the activity-based detection of SCRAs. In this study, we evaluated whether (synthetic) cannabinoid activity can be dete...
Article
Full-text available
2,5-Dimethoxy-4-ethylphenethylamine (2C-E) is psychedelic phenylethylamine, with a chemical structure similar to mescaline, used as new psychoactive substance (NPS). It inhibits norepinephrine and serotonin uptake and, more relevant, acts as a partial agonist of the serotonin 2A (5-HT2A), 2B (5-HT2B), and (5-HT2C) receptors. Consumers have reported...
Article
Full-text available
Rationale 5-methoxy-N,N-dimethyltryptamine is a psychotropic substance found in various plant and animal species and is synthetically produced. 5-methoxy-N,N-dimethyltryptamine is used in naturalistic settings for spiritual exploration, recreation, or to address negative affect and mood problems. However, scientific knowledge on the effects of 5-me...