Featured Research

from universities, journals, and other organizations

Minimal Relationship Between Cannabis And Schizophrenia Or Psychosis, Suggested By New Study

Date:
October 22, 2009
Source:
Wiley-Blackwell
Summary:
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 new study has determined that it may be necessary to stop thousands of cannabis users in order to prevent a single case of schizophrenia.

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 new study has determined that it may be necessary to stop thousands of cannabis users in order to prevent a single case of schizophrenia.

Scientists from Bristol, Cambridge and the London School of Hygiene and Tropical Medicine took the latest information on numbers of cannabis users, the risk of developing schizophrenia, and the risk that cannabis use causes schizophrenia to estimate how many cannabis users may need to be stopped to prevent one case of schizophrenia. The study found it would be necessary to stop 2800 heavy cannabis users in young men and over 5000 heavy cannabis users in young women to prevent a single case of schizophrenia. Among light cannabis users, those numbers rise to over 10,000 young men and nearly 30,000 young women to prevent one case of schizophrenia.

That's just part of the story. Interventions to prevent cannabis use typically do not succeed for every person who is treated. Depending on how effective an intervention is at preventing cannabis use, it would be necessary to treat even higher numbers of users to achieve the thousands of successful results necessary to prevent a very few cases of schizophrenia.

Matt Hickman, one of the authors of the report recently published in the journal Addiction, said that "preventing cannabis use is important for many reasons -- including reducing tobacco and drug dependence and improving school performance. But our evidence suggests that focusing on schizophrenia may have been misguided. Our research cannot resolve the question whether cannabis causes schizophrenia, but does show that many people need to give up cannabis in order to have an impact on the number of people with schizophrenia. The likely impact of re-classifying cannabis in the UK on schizophrenia or psychosis incidence is very uncertain."


Story Source:

The above story is based on materials provided by Wiley-Blackwell. Note: Materials may be edited for content and length.


Journal Reference:

  1. 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

Cite This Page:

Wiley-Blackwell. "Minimal Relationship Between Cannabis And Schizophrenia Or Psychosis, Suggested By New Study." ScienceDaily. ScienceDaily, 22 October 2009. <www.sciencedaily.com/releases/2009/10/091022101538.htm>.
Wiley-Blackwell. (2009, October 22). Minimal Relationship Between Cannabis And Schizophrenia Or Psychosis, Suggested By New Study. ScienceDaily. Retrieved April 19, 2014 from www.sciencedaily.com/releases/2009/10/091022101538.htm
Wiley-Blackwell. "Minimal Relationship Between Cannabis And Schizophrenia Or Psychosis, Suggested By New Study." ScienceDaily. www.sciencedaily.com/releases/2009/10/091022101538.htm (accessed April 19, 2014).

Share This



More Mind & Brain News

Saturday, April 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Study On Artists' Brain Shows They're 'Structurally Unique'

Study On Artists' Brain Shows They're 'Structurally Unique'

Newsy (Apr. 17, 2014) The brains of artists aren't really left-brain or right-brain, but rather have extra neural matter in visual and motor control areas. Video provided by Newsy
Powered by NewsLook.com
Is Apathy A Sign Of A Shrinking Brain?

Is Apathy A Sign Of A Shrinking Brain?

Newsy (Apr. 17, 2014) A recent study links apathetic feelings to a smaller brain. Researchers say the results indicate a need for apathy screening for at-risk seniors. Video provided by Newsy
Powered by NewsLook.com
Are School Dress Codes Too Strict?

Are School Dress Codes Too Strict?

AP (Apr. 16, 2014) Pushing the limits on style and self-expression is a rite of passage for teens and even younger kids. How far should schools go with their dress codes? The courts have sided with schools in an era when school safety is paramount. (April 16) Video provided by AP
Powered by NewsLook.com
Could Even Casual Marijuana Use Alter Your Brain?

Could Even Casual Marijuana Use Alter Your Brain?

Newsy (Apr. 16, 2014) A new study conducted by researchers at Northwestern and Harvard suggests even casual marijuana use can alter your brain. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins