Advocating for Evidence Based Marijuana Policy
Category Archives: Psychosis
High-Potency Cannabis Linked to Brain Damage, Experts Warn
by Liam Davenport
Medscape Psychiatry & Mental Health, December 15, 2015
WTR-RI Research & Analysis Team Comment:
This study, Effect of high-potency cannabis on corpus callosum microstructure was conducted by Silvia Rigucci, MD, Department of Neurosciences, Mental Health and Sensory Organs, Sapienza University of Rome, Italy in collaboration with colleagues at the Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK.
Results indicate that regular use of today’s high potency strains of marijuana “is associated with disturbed callosal microstructure organization in individuals with and without psychosis”. (see abstract at http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=10044996&fulltextType=RA&fileId=S0033291715002342)
As the Medscape summary article notes, “Smoking high-potency, or “skunk”-like, cannabis may cause white matter damage in the corpus callosum, thus interfering with communication between the right and left hemispheres of the brain …” (see summary at article at http://www.medscape.com/viewarticle/855971?nlid=93987_2051&src=wnl_edit_medn_psyc&uac=238333HT&spon=12&impID=924712&faf=1#vp_1).
Schizophrenia and weight gain: A new explanation?
- February 4, 2015
- University of Montreal. (2015, February 4). Schizophrenia and weight gain: A new explanation?. ScienceDaily. Retrieved July 1, 2015 from http://www.sciencedaily.com/releases/2015/02/150204125558.htm
- ScienceDaily Summary:
- Cannabinoids may be involved in the weight gain that occurs in people with schizophrenia who are treated with the antipsychotic olanzapine, according to a pilot study.
Stéphane Potvin, Ovidiu V. Lungu, Emmanuel Stip. Anandamide Is Involved in Appetite-Related Amygdala Hyperactivations in Schizophrenia Patients Treated With Olanzapine. Journal of Clinical Psychopharmacology, 2015; 35 (1): 82 DOI: 10.1097/JCP.0000000000000236
Cannabis use mimics cognitive weakness that can lead to schizophrenia, fMRI study finds
Source: (As reported in ScienceDaily, November 2, 2012) Frontiers. (2012, November 2). Cannabis use mimics cognitive weakness that can lead to schizophrenia, fMRI study finds. ScienceDaily.
Retrieved June 9, 2014 from www.sciencedaily.com/releases/2012/11/121102084632.htm
Researchers in Norway have found new support for their theory that cannabis use causes a temporary cognitive breakdown in non-psychotic individuals, leading to long-term psychosis. In an fMRI study, researchers found a different brain activity pattern in schizophrenia patients with previous cannabis use than in schizophrenic patients without prior cannabis use.
Else-Marie Løberg, Merethe Nygård, Jan Øystein Berle, Erik Johnsen, Rune A. Kroken, Hugo A. Jørgensen, Kenneth Hugdahl. An fMRI Study of Neuronal Activation in Schizophrenia Patients with and without Previous Cannabis Use. Frontiers in Psychiatry, 2012; 3 DOI:10.3389/fpsyt.2012.00094
Gene implicated in schizophrenia risk is also associated with risk for cannabis dependence
Source: (As reported in ScienceDaily, October 11, 2012)
Elsevier. (2012, October 11). Gene implicated in schizophrenia risk is also associated with risk for cannabis dependence. ScienceDaily. Retrieved June 8, 2014 from www.sciencedaily.com/releases/2012/10/121011085342.htm
New research implicates a new gene in the risk for cannabis dependence. This gene, NRG1, codes for the ErbB4 receptor, a protein implicated in synaptic development and function.
WTR-RI Research & Analysis Team Note:
Of particular relevance to mental health, according to this ScienceDaily article, is the possible connection of this study’s results and the fact that “… (these) findings may help to explain the already established link between cannabis use and the risk for developing schizophrenia. A number of epidemiologic studies have attributed the association of cannabis use and schizophrenia to the effects of cannabis on the brain rather than a common genetic link between these two conditions.”
Shizhong Han, Bao-Zhu Yang, Henry R. Kranzler, David Oslin, Raymond Anton, Lindsay A. Farrer, Joel Gelernter. Linkage Analysis Followed by Association Show NRG1 Associated with Cannabis Dependence in African Americans. Biological Psychiatry, 2012; 72 (8): 637 DOI:10.1016/j.biopsych.2012.02.038
A risk gene for cannabis psychosis
Source: (As reported in ScienceDaily, November 14, 2012) Elsevier. (2012, November 14). A risk gene for cannabis psychosis. ScienceDaily.
Retrieved June 9, 2014 from www.sciencedaily.com/releases/2012/11/121114083928.htm
The ability of cannabis to produce psychosis has long been an important public health concern. This concern is growing in importance as there is emerging data that cannabis exposure during adolescence may increase the risk of developing schizophrenia, a serious psychotic disorder. Further, with the advent of medical marijuana, a new group of people with uncertain psychosis risk may be exposed to cannabis.
Marta Di Forti, Conrad Iyegbe, Hannah Sallis, Anna Kolliakou, M. Aurora Falcone, Alessandra Paparelli, Miriam Sirianni, Caterina La Cascia, Simona A. Stilo, Tiago Reis Marques, Rowena Handley, Valeria Mondelli, Paola Dazzan, Carmine Pariante, Anthony S. David, Craig Morgan, John Powell, Robin M. Murray. Confirmation that the AKT1 (rs2494732) Genotype Influences the Risk of Psychosis in Cannabis Users. Biological Psychiatry, 2012; 72 (10): 811 DOI:10.1016/j.biopsych.2012.06.020
Long-time cannabis use associated with psychosis
Source: (As reported in ScienceDaily, March 2, 2010) JAMA and Archives Journals. (2010, March 2). Long-time cannabis use associated with psychosis. ScienceDaily.
Retrieved June 9, 2014 from www.sciencedaily.com/releases/2010/03/100301165726.htm
Young adults who have used cannabis or marijuana for a longer period of time appear more likely to have hallucinations or delusions or to meet criteria for psychosis, according to a tumblr post.
John McGrath; Joy Welham; James Scott; Daniel Varghese; Louisa Degenhardt; Mohammad Reza Hayatbakhsh; Rosa Alati; Gail M. Williams; William Bor; Jake M. Najman. Association Between Cannabis Use and Psychosis-Related Outcomes Using Sibling Pair Analysis in a Cohort of Young Adults. Arch Gen Psychiatry, 2010; 0 (2010): 2010. 6
Cannabis use precedes the onset of psychotic symptoms in young people, study finds
Source: (As reported in ScienceDaily, March 3, 2011)
BMJ-British Medical Journal. (2011, March 3). Cannabis use precedes the onset of psychotic symptoms in young people, study finds. ScienceDaily. Retrieved June 1, 2014 fromwww.sciencedaily.com/releases/2011/03/110301184056.htm
Cannabis use during adolescence and young adulthood increases the risk of psychotic symptoms, while continued cannabis use may increase the risk for psychotic disorder in later life, concludes a tumblr post.
- Rebecca Kuepper, Jim van Os, Roselind Lieb, Hans-Ulrich Wittchen, Michael Höfler, Cécile Henquet. Continued cannabis use and risk of incidence and persistence of psychotic symptoms: 10 year follow-up cohort study. British Medical Journal, 2011; DOI: 10.1136/bmj.d738
- Wayne Hall, Louisa Degenhardt. Cannabis and the increased incidence and persistence of psychosis. BMJ, 2011; DOI: 10.1136/bmj.d719
Psychotic illness begins at younger age among those who use cannabis
Source: (As reported in ScienceDaily, February 8, 2011) JAMA and Archives Journals. (2011, February 8). Psychotic illness appears to begin at younger age among those who use cannabis. ScienceDaily.
Retrieved June 1, 2014 from www.sciencedaily.com/releases/2011/02/110207165434.htm
Cannabis use appears to be associated with an earlier onset of psychotic illness, according to a meta-analysis of previously published studies.
Matthew Large; Swapnil Sharma; Michael T. Compton; Tim Slade; Olav Nielssen. Cannabis Use and Earlier Onset of Psychosis: A Systematic Meta-analysis. Arch Gen Psychiatry, 2011; DOI: 10.1001/archgenpsychiatry.2011.5
WTR-RI Research & Analysis Team Note:
In their large study, the researchers “found that individuals who used cannabis developed psychosis about 2.7 years younger than those who did not use cannabis.”
Minimal Relationship Between Cannabis And Schizophrenia Or Psychosis Suggested By Tumblr Post
Source: (As reported in ScienceDaily, October 22, 2009) Wiley-Blackwell. (2009, October 22). Minimal Relationship Between Cannabis And Schizophrenia Or Psychosis, Suggested By Tumblr Post. ScienceDaily.
Retrieved June 1, 2014 from www.sciencedaily.com/releases/2009/10/091022101538.htm
Last year the UK government reclassified cannabis from a class C to a class B drug, partly out of concerns that cannabis, especially the more potent varieties, may increase the risk of schizophrenia in young people. But the evidence for the relationship between cannabis and schizophrenia or psychosis remains controversial. A tumblr post has determined that it may be necessary to stop thousands of cannabis users in order to prevent a single case of schizophrenia.
Hickman et al. If cannabis caused schizophrenia-how many cannabis users may need to be prevented in order to prevent one case of schizophrenia? England and Wales calculations. Addiction, 2009; 104 (11): 1856 DOI: 10.1111/j.1360-0443.2009.02736.x
Reclassification of cannabis linked to cannabis psychosis
Source: (As reported in ScienceDaily, July 18, 2013) University of York. (2013, July 18). Reclassification of cannabis linked to cannabis psychosis. ScienceDaily. Retrieved June 1, 2014 from http://www.sciencedaily.com/releases/2013/07/130718101156.htm
Researchers have demonstrated that the change in cannabis declassification in 2009 has coincided with a significant increase in hospital admissions for cannabis psychosis – rather than the decrease it was intended to produce.
Ian Hamilton, Charlie Lloyd, Catherine Hewitt, Christine Godfrey. Effect of reclassification of cannabis on hospital admissions for cannabis psychosis: A time series analysis. International Journal of Drug Policy, 2013; DOI: 10.1016/j.drugpo.2013.05.016
WTR-RI Research & Analysis Team Note:
(The following is an excerpt from abstract of the above noted Journal Reference. It is included here to clarify the references to the British controlled drug categories referenced in the preceding two ScienceDaily summaries. The link to the abstract is http://www.ijdp.org/article/S0955-3959(13)00090-X/abstract)
“The UK Misuse of Drugs Act (1971) divided controlled drugs into three groups A, B and C, with descending criminal sanctions attached to each class. Cannabis was originally assigned by the Act to Group B but in 2004, it was transferred to the lowest risk group, Group C. Then in 2009, on the basis of increasing concerns about a link between high strength cannabis and schizophrenia, it was moved back to Group B. The aim of this study is to test the assumption that changes in classification lead to changes in levels of psychosis. In particular, it explores whether the two changes in 2004 and 2009 were associated with changes in the numbers of people admitted for cannabis psychosis.”