Call for Evidence on Cannabis - Royal College of Psychiatrists

About the Review

The Royal College of Psychiatrists is undertaking a review to develop a College position on:

  • cannabis use in the UK and how this relates to mental health, incorporating evidence on the biological, psychological and social effects of cannabis;
  • the use of medicinal cannabis in relation to mental illness.

About this Call for Evidence

We are asking those with expertise and personal experience of medicinal cannabis and cannabis for recreational use to contribute to its review by providing relevant evidence. Those who might wish to respond are:

  • Academics with experience in these fields;
  • patients/service users;
  • carers and family members;
  • members of staff in mental health services (NHS, independent, or voluntary);
  • providers of mental health services (NHS, independent, or voluntary);
  • charities or voluntary sector organisations with an interest in this area;
  • individuals or organisations working in the criminal justice system;
  • other relevant people, bodies or groups. 

Responses will be used to inform our areas of inquiry and final reports.

Submit a response

To submit your response to this call for evidence please complete the below form and return it to policy [at] rcpsych [dot] ac [dot] uk by 5 pm on Monday 10th June 2019.

Jose Luis Vazquez Martinez

Science and policy are often in tension with one another. Such is the case with the evolution of marijuana policy over the past several years as implemented by the states.

Jose Luis Vazquez Martinez

Harvard Medical School professor and one of the nation’s leading experts on marijuana, Dr. Bertha Madras visit Adlai E. Stevenson High School on September 13, 2016 to give a public talk. Dr.

Jose Luis Vazquez Martinez

Hear a fascinating presentation by Dr. Nora Volkow, Director of the National Institute on Drug Abuse, about the effects of marijuana use on the brain, body and behavior. Dr. Volkow's remarks were given on Feb. 4th at CADCA's 24th National Leadership Forum.

Cannabidiol (CBD) Content in Vaporized Cannabis does not Prevent Tetrahydrocannabinol (THC)-induced Impairment of Driving and Cognition



The main psychoactive component of cannabis, delta-9-tetrahydrocannabinol (THC), can impair driving performance. Cannabidiol (CBD), a non-intoxicating cannabis component, is thought to mitigate certain adverse effects of THC. It is possible then that cannabis containing equivalent CBD and THC will differentially affect driving and cognition relative to THC-dominant cannabis.


The present study investigated and compared the effects of THC-dominant and THC/CBD equivalent cannabis on simulated driving and cognitive performance.


In a randomized, double-blind, within-subjects crossover design, healthy volunteers (n = 14) with a history of light cannabis use attended three outpatient experimental test sessions in which simulated driving and cognitive performance were assessed at two timepoints (20–60 min and 200–240 min) following vaporization of 125 mg THC-dominant (11% THC; < 1% CBD), THC/CBD equivalent (11% THC, 11% CBD), or placebo (< 1% THC/CBD) cannabis.


Both active cannabis types increased lane weaving during a car-following task but had little effect on other driving performance measures. Active cannabis types impaired performance on the Digit Symbol Substitution Task (DSST), Divided Attention Task (DAT) and Paced Auditory Serial Addition Task (PASAT) with impairment on the latter two tasks worse with THC/CBD equivalent cannabis. Subjective drug effects (e.g., “stoned”) and confidence in driving ability did not vary with CBD content. Peak plasma THC concentrations were higher following THC/CBD equivalent cannabis relative to THC-dominant cannabis, suggesting a possible pharmacokinetic interaction.


Cannabis containing equivalent concentrations of CBD and THC appears no less impairing than THC-dominant cannabis, and in some circumstances, CBD may actually exacerbate THC-induced impairment.

Workplace Alcohol and Other Drug Factsheets

To assist workplaces to respond to alcohol and other drug-related harm in the workplace, The National Centre for Education and Training on Addiction, has produced a series of factsheets about commonly used drugs and their impact on safety and well-being of individual employees, and overall safety and productivity of the workplace. 

Fact sheets cover the following topics:

  1. Alcohol and Work
  2. Cannabis and Work
  3. Amphetamine and Work
  4. Ecstasy and Work
  5. Other Illicit Drugs and Work
  6. Prescription Drugs and Work 
  7. Tobacco and Work
Jose Luis Vazquez Martinez

The evidence linking cannabis use to schizophrenia is compelling. No one who is truly open-minded and rational can dismiss the possibility that cannabis exposure causes schizophrenia (or a schizophrenia-identical persisting psychotic disorder).

Jose Luis Vazquez Martinez

A short film with information about cannabis and the risk of psychosis.

Cannabis Policy and Legislation in the Nordic Countries

Cannabis is used throughout the Nordic countries, with a particular increase in use among young adults.

Markets and attitudes towards the drug have evolved, therefore there is a need to understand follow societies response to its use.

This report looks at the similarities and differences in legislation and the ways in which the law is enacted in legal practice, police work, and many other areas.

As well as providing a summary of the latest trends of cannabis use, the publication provides an overview of cannabis control, police registered drug offences, the illegal drug market and the penalty system in Denmark, Finland, Norway, Iceland and Sweden.

Jose Luis Vazquez Martinez

Conferencia transmitida el 2 de Mayo de 2018. La actual discusión sobre una posible legalización de la marihuana para uso recreativo nos obliga a buscar información sobre el tema, a fin de tomar una posición informada.

Jose Luis Vazquez Martinez

Presented by Denise Walker, PhD, Innovative Programs Research Group, University of Washington. How do you engage with clients who are using marijuana heavily, but not interested in treatment?

Jose Luis Vazquez Martinez

El Instituto de Atención y Prevención de las Adicciones de la Ciudad de México (IAPA) nos explica por qué la planta de la mariguana, en sí misma, no es una medicina.