Background : Psychotic experiences (PEs) are common in the general population, and can be an early sign of psychotic disorders, which can have a large impact on people’s lives. Understanding the causes and consequences of PEs is therefore important, both for identifying potential causal risk factors for PEs and for exploring how PEs may subsequently affect people’s beliefs and behaviours. To...
medRxivMay 29, 2025Paul B. Fitzgerald, Sara Webb, Nigel Christopher Denning et al.2 citations
preprint
Abstract Objective Despite many decades of experimental studies and clinical trials involving a variety of psychedelic agents, we still lack a comprehensive understanding of the effects of these substances on psychological experiences. As such, we designed and conducted a study to comprehensively characterise the effects of both psilocybin and 3,4-Methylenedioxymethamphetamine (MDMA) on a range...
INTRODUCTION: While evidence strongly supports a causal effect of cannabis on psychosis, it is less clear whether the symptom pattern, clinical course, and outcomes differ in cases of schizophrenia with and without a background of cannabis use. METHODS: Analysis of medical records from a longitudinal follow-up of Swedish conscripts with data on cannabis use in adolescence and subsequent...
Associations between cannabis use and psychotic outcomes are consistently reported, but establishing causality from observational designs can be problematic. We review the evidence from longitudinal studies that have examined this relationship and discuss the epidemiologic evidence for and against interpreting the findings as causal. We also review the evidence identifying groups at...
BACKGROUND: Sleep disturbances are commonly reported in the psychosis prodrome, but rarely explored in relation to psychotic experiences. AIMS: To investigate the relationship between specific parasomnias (nightmares, night terrors and sleepwalking) in childhood and later adolescent psychotic experiences. METHOD: The sample comprised 4720 individuals from a UK birth cohort. Mothers reported on...
Study objectives: To examine associations between specific parasomnias and psychotic experiences in childhood. Design: Birth cohort study. Information on the presence of frequent nightmares in children was obtained prospectively from mothers during multiple assessments conducted when children were aged between 2.5 and 9 y. Children were interviewed at age 12 y about nightmares, night terrors,...
This chapter updates our knowledge of the short- and long-term effects of cannabis on cognition based on integrating evidence from the most recent literature on this topic. Numerous studies have examined the acute effects of cannabis on human cognition. Cannabis induces perceptual distortions and impairs memory and concentration during acute intoxication. Studies of long-term and heavy cannabis...
BACKGROUND: It is unclear if research findings support clinical opinion that cannabis use leads to worse outcomes in people with psychosis, or whether this impression is confounded by other factors. AIMS: To systematically review the evidence pertaining to whether cannabis affects outcome of psychotic disorders. METHOD: We searched 10 relevant databases (to November 2006), reference lists of...
BACKGROUND: Non-clinical psychotic symptoms appear common in children, but it is possible that a proportion of reported symptoms result from misinterpretation. There is a well-established association between pre-morbid low IQ score and schizophrenia. Psychosis-like symptoms in children may also be a risk factor for psychotic disorder but their relationship with IQ is unclear. AIMS: To...
Evidence for an association between cannabis use and psychosis continues to accumulate. A number of population-based longitudinal studies have found that cannabis use is associated with the later development of psychotic symptoms or psychotic diagnoses [1–6]. Studies of subjects with schizophrenia show associations between cannabis use and increased levels of positive symptoms [7,8] as well as...