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Full-Text Articles in Social and Behavioral Sciences

Cannabis-Induced Psychosis-Like Experiences Are Associated With High Schizotypy, Emma Barkus, John Stirling, Richard Hopkins, Shon Lewis Dec 2011

Cannabis-Induced Psychosis-Like Experiences Are Associated With High Schizotypy, Emma Barkus, John Stirling, Richard Hopkins, Shon Lewis

Emma Barkus

OBJECTIVE: Recent studies have suggested that cannabis use is a risk factor for developing schizophrenia. We tested the hypothesis that cannabis use increases the likelihood of psychosis-like experiences in non-clinical participants who scored highly on a measure of schizotypy. METHOD: The psychological effects of cannabis were assessed in 137 healthy individuals (76% female, mean age 22 years) using a newly developed questionnaire concerned with subjective experiences of the drug: the Cannabis Experiences Questionnaire. The questionnaire has three subscales: Pleasurable Experiences, Psychosis-Like Experiences and After-Effects. Respondents also completed the brief Schizotypal Personality Questionnaire. RESULTS: Cannabis use was reported by 72% of …


Cannabis-Induced Psychotic-Like Experiences Are Predicted By High Schizotypy. Confirmation Of Preliminary Results In A Large Cohort., John Stirling, Emma Barkus, L Nabosi, S Irshad, G Roemer, B Schreudergoidheijt, Shon Lewis Dec 2011

Cannabis-Induced Psychotic-Like Experiences Are Predicted By High Schizotypy. Confirmation Of Preliminary Results In A Large Cohort., John Stirling, Emma Barkus, L Nabosi, S Irshad, G Roemer, B Schreudergoidheijt, Shon Lewis

Emma Barkus

Background: Cannabis use has been identified as a possible risk factor for developing schizophrenia. In a previous paper we reported preliminary evidence that cannabis use increases the likelihood of psychosis-like experiences in non-clinical respondents who scored highly on a measure of schizotypy. We now present findings from pooled data from 3 new follow-up studies comprising a sample of 477 respondents, of whom 332 reported using cannabis at least once. Sampling and Methods: As in our previous study, the psychological effects of cannabis were assessed with the Cannabis Experiences Questionnaire, from which 3 subscales can be derived; encompassing pleasurable experiences, psychosis-like …


Schizotypy And Psychosis-Like Experiences From Recreational Cannabis In A Non-Clinical Sample, Emma Barkus, Shon Lewis Dec 2011

Schizotypy And Psychosis-Like Experiences From Recreational Cannabis In A Non-Clinical Sample, Emma Barkus, Shon Lewis

Emma Barkus

Background. The relationship between cannabis use and psychosis is still a matter for debate. Accounting for the individual differences in subjective experiences to recreational cannabis use in the general population may hold some clues to the aetiological relationship between cannabis and psychotic symptoms. We hypothesized that schizotypy would account for the individual differences in subjective experiences after cannabis use but not in patterns of use. Method. In a sample of 532 young people who had used cannabis at least once, we examined the relationship between the Cannabis Experiences Questionnaire (CEQ) and the Schizotypal Personality Questionnaire (SPQ). Additionally, we examined the …


Personality And Cannabis Use, Emma Barkus Dec 2011

Personality And Cannabis Use, Emma Barkus

Emma Barkus

Cannabis is one of the most widely used illegal substances in the world. Its use has been reported to be over-represented in many psychiatric conditions and has frequently been found to predate the onset of psychiatric symptoms. However, cannabis may also have detrimental effects on the general population. Factors that predict the onset of use are receiving increased attention to aid in identifying groups of young people who may be more prone to consume cannabis. Personality traits may be one such factor as they are readily identifiable and offer information that can be used for improved targeting of educational material …


Cerebellar White-Matter Changes In Cannabis Users With And Without Schizophrenia, N Solowij, M Yucel, C Respondek, S Whittle, E Lindsay, C Pantelis, D I. Lubman Jan 2011

Cerebellar White-Matter Changes In Cannabis Users With And Without Schizophrenia, N Solowij, M Yucel, C Respondek, S Whittle, E Lindsay, C Pantelis, D I. Lubman

Faculty of Health and Behavioural Sciences - Papers (Archive)

Background. The cerebellum is rich in cannabinoid receptors and implicated in the neuropathology of schizophrenia. Long-term cannabis use is associated with functional and structural brain changes similar to those evident in schizophrenia, yet its impact on cerebellar structure has not been determined. We examined cerebellar grey and white matter in cannabis users with and without schizophrenia. Method. Seventeen patients with schizophrenia and 31 healthy controls were recruited ; 48% of the healthy group and 47% of the patients were long-term heavy cannabis users (mean 19.7 and 17.9 years near daily use respectively). Cerebellar measures were extracted from structural 3-T magnetic …


Verbal Learning And Memory In Adolescent Cannabis Users, Alcohol Users And Non-Users, Nadia Solowij, Katy A. Jones, Megan E. Rozman, Sasha M. Davis, Joseph Ciarrochi, Patrick C. L Heaven, Dan I. Lubman, Murat Yucel Jan 2011

Verbal Learning And Memory In Adolescent Cannabis Users, Alcohol Users And Non-Users, Nadia Solowij, Katy A. Jones, Megan E. Rozman, Sasha M. Davis, Joseph Ciarrochi, Patrick C. L Heaven, Dan I. Lubman, Murat Yucel

Faculty of Health and Behavioural Sciences - Papers (Archive)

Rationale Long-term heavy cannabis use can result in memory impairment. Adolescent users may be especially vulnerable to the adverse neurocognitive effects of cannabis. Objectives and methods In a cross-sectional and prospective neuropsychological study of 181 adolescents aged 16–20 (mean 18.3 years), we compared performance indices from one of the most widely used measures of learning and memory—the Rey Auditory Verbal Learning Test—between cannabis users (n=52; mean 2.4 years of use, 14 days/month, median abstinence 20.3 h), alcohol users (n=67) and non-user controls (n=62) matched for age, education and premorbid intellectual ability (assessed prospectively), and alcohol consumption for cannabis and alcohol …


Cannabis And Cognition: Short- And Long-Term Effects, Nadia Solowij, Nicole Pesa Jan 2011

Cannabis And Cognition: Short- And Long-Term Effects, Nadia Solowij, Nicole Pesa

Faculty of Health and Behavioural Sciences - Papers (Archive)

Twenty years ago cannabis was generally perceived to be a benign drug with few significant adverse effects. As outlined elsewhere in this book, evidence has since mounted in the scientific literature for a range of harms associated with the use of cannabis, including the development of dependence and health-related harms (see also Hall and Solowij, 1998; Hall and Degenhardt, 2009). As the overall theme of this book indicates, an association between cannabis use and the development of psychotic symptoms or overt psychosis has grown to be recognized as a significant potential harm, and investigating the mechanisms by which cannabis may …