In the realm of cognitive science, the quest to understand cognitive control has persisted for decades. Traditional notions of cognitive control have focused on inhibition through the prefrontal... Show moreIn the realm of cognitive science, the quest to understand cognitive control has persisted for decades. Traditional notions of cognitive control have focused on inhibition through the prefrontal cortex, but this dissertation challenges that perspective with a more comprehensive framework: The Metacontrol State Model (MSM). The MSM proposes that cognitive control emerges from the interplay between two opposing systems – one promoting flexibility and the other promoting persistence. These systems interact to shape our cognitive processing styles, thereby influencing our ability to effectively regulate our actions. This dissertation explores questions such as why individuals exhibit differences in cognitive control capacity and how state-related changes and trait-related predispositions impact cognitive control function. The overarching goal of this dissertation is to empirically test the MSM model and shed light on the factors that influence cognitive control. Through a series of experiments, it seeks to understand how altered states of consciousness, achieved through meditation techniques or serotonergic psychedelics, affect the balance between intentional and habitual processes. Additionally, it examines the extent to which individual trait biases serve as trans-diagnostic markers in various psychopathologies. This work comprises a literature review and six empirical articles. By integrating theory and empirical research, this dissertation takes us on a journey into the intricate world of cognitive control, shaping our understanding of how it influences our lives. Show less
Breeksema, J.J.; Kuin, B.W.; Kamphuis, J.; Brink, W. van den; Vermetten, E.; Schoevers, R.A. 2022
Introduction: Small-scale clinical studies with psychedelic drugs have shown promising results for the treatment of several mental disorders. Before psychedelics become registered medicines, it is... Show moreIntroduction: Small-scale clinical studies with psychedelic drugs have shown promising results for the treatment of several mental disorders. Before psychedelics become registered medicines, it is important to know the full range of adverse events (AEs) for making balanced treatment decisions. Objective: To systematically review the presence of AEs during and after administration of serotonergic psychedelics and 3,4-methyenedioxymethamphetamine (MDMA) in clinical studies. Methods: We systematically searched PubMed, PsycINFO, Embase, and ClinicalTrials.gov for clinical trials with psychedelics since 2000 describing the results of quantitative and qualitative studies. Results: We included 44 articles (34 quantitative + 10 qualitative), describing treatments with MDMA and serotonergic psychedelics (psilocybin, lysergic acid diethylamide, and ayahuasca) in 598 unique patients. In many studies, AEs were not systematically assessed. Despite this limitation, treatments seemed to be overall well tolerated. Nausea, headaches, and anxiety were commonly reported acute AEs across diagnoses and compounds. Late AEs included headaches (psilocybin, MDMA), fatigue, low mood, and anxiety (MDMA). One serious AE occurred during MDMA administration (increase in premature ventricular contractions requiring brief hospitalization); no other AEs required medical intervention. Qualitative studies suggested that psychologically challenging experiences may also be therapeutically beneficial. Except for ayahuasca, a large proportion of patients had prior experience with psychedelic drugs before entering studies. Conclusions: AEs are poorly defined in the context of psychedelic treatments and are probably underreported in the literature due to study design (lack of systematic assessment of AEs) and sample selection. Acute challenging experiences may be therapeutically meaningful, but a better understanding of AEs in the context of psychedelic treatments requires systematic and detailed reporting. Show less
Prochazkova, L.; Lippelt, D.P.; Colzato, L.S.; Kuchar, M.; Sjoerds, Z.; Hommel, B. 2018
IntroductionTaking microdoses (a mere fraction of normal doses) of psychedelic substances, such as truffles, recently gained popularity, as it allegedly has multiple beneficial effects including... Show moreIntroductionTaking microdoses (a mere fraction of normal doses) of psychedelic substances, such as truffles, recently gained popularity, as it allegedly has multiple beneficial effects including creativity and problem-solving performance, potentially through targeting serotonergic 5-HT2A receptors and promoting cognitive flexibility, crucial to creative thinking. Nevertheless, enhancing effects of microdosing remain anecdotal, and in the absence of quantitative research on microdosing psychedelics, it is impossible to draw definitive conclusions on that matter. Here, our main aim was to quantitatively explore the cognitive-enhancing potential of microdosing psychedelics in healthy adults.MethodsDuring a microdosing event organized by the Dutch Psychedelic Society, we examined the effects of psychedelic truffles (which were later analyzed to quantify active psychedelic alkaloids) on two creativity-related problem-solving tasks: the Picture Concept Task assessing convergent thinking and the Alternative Uses Task assessing divergent thinking. A short version of the Ravens Progressive Matrices task assessed potential changes in fluid intelligence. We tested once before taking a microdose and once while the effects were expected to be manifested.ResultsWe found that both convergent and divergent thinking performance was improved after a non-blinded microdose, whereas fluid intelligence was unaffected.ConclusionWhile this study provides quantitative support for the cognitive-enhancing properties of microdosing psychedelics, future research has to confirm these preliminary findings in more rigorous placebo-controlled study designs. Based on these preliminary results, we speculate that psychedelics might affect cognitive metacontrol policies by optimizing the balance between cognitive persistence and flexibility. We hope this study will motivate future microdosing studies with more controlled designs to test this hypothesis. Show less
