Although cannabis is less harmful to health than tobacco and alcohol and not in the same league as other drugs such as cocaine and heroin, regular use, over time, is associated with significant health risks.1 To date the discussions around cannabis have focused, rather unhelpfully, on whether or not cannabis should be legalised, or which Class (of the Misuse of Drugs Act, 1971) cannabis should be placed. At the end of January this year cannabis was reclassified by the government from a Class C to a Class B drug. This debate has served as a distraction to the real issue of how to help people understand the risks they face when they use the drug and ways that they can minimise these risks.
There are a significant number of studies (animal and human) that confirm that regular cannabis use can cause serious lung disease (for example, bullous emphysema, bronchitis, and lung cancer); problems with concentration (increasing the risk of vehicle accident and other accidents); amotivation (leading to scholastic failure); mental health problems (anxiety, paranoia, and panic disorder); and dependence (around 5–10% of users become psychologically dependent). Larger amounts of cannabis can produce psychotic states lasting several days. Cannabis use has been linked to schizophrenia, with a recent study showing an increased risk of psychosis with estimates that some cannabis users (those with a genetic disposition) have, on average, a 41% greater risk of developing psychosis than non-users.2
Most cannabis use is intermittent and self-limiting, with individuals stopping in their mid-twenties. However, for a significant minority, use becomes continuous and problematic: around 10% of people who use cannabis become daily users and around 20% weekly. The risks associated with cannabis vary depending on the route of use (smoking is more harmful than oral use); length of use (many of the effects are dose related); concomitant use with tobacco; age of use (use at young teens is thought to increase the risk of later psychosis than starting at a later age);2 and genetic predisposition. The type of cannabis used also affects the risk of harmful effects. People who smoke the more powerful kind of cannabis known as skunk are at greatest risk. The potency of cannabis has increased over the past 10 years, with more concentrated forms now on sale.
THE ROLE OF THE GP AND REDUCING RISK
Given the prevalence of cannabis use (being the third most widely used drug in the UK, and the most widely used illegal drug), GPs can expect to have individuals consulting with them who use the drug. Uniquely among health professionals, GPs are ideally placed to counsel patients about the risks and harms they may face and ways of reducing these.1 GPs have an important role in providing accurate information about cannabis (as well as other common drugs) to users, potential users, and families of users. The Care Services Improvement Partnership (CSIP) have produced a number of toolkits to support GPs in delivering the mental health messages across to their patients.3
The paper in this issue of the Journal4 has shown that a similar technique can be used with cannabis users. This paper and like its predecessors shows again the important role that GPs can have in improving the health of their patients.
Put simply, the harm reduction and health improvement messages that GPs need to get across are:
Cannabis can cause harm in much the same way that smoking cigarettes can harm. The habit of inhaling deeply and holding the smoke is thought to increase the risk of lung disease.
Cannabis can cause dependence and anyone using on a regular basis or heavy users should consider seeking help.
There appears to be a link between cannabis use and psychosis, especially apparent where the individual begins to smoke the drug at an early age (under 18 years), therefore avoid using at all if you are under 18 years of age.
That smoking cannabis and driving increases the risks of accidents, therefore NEVER use cannabis and drive or operate machinery.
Reduce or avoid using cannabis with alcohol as this can enhance the negative and risky effects of both substances.
Address tobacco addiction.
BRIEF INTERVENTIONS
For a number of decades now we have known how effective a few minutes (sometimes as little as 2 minutes) spent talking to a patient about risky lifestyle behaviour5 (smoking, alcohol,6 and obesity) can influence that behaviour.7
Brief and minimal intervention fits within the 10 minute consultation. The components can be summarised by the acronym FRAMES.
Feedback of personal risk based on symptoms presented, results of tests, and behaviour.
Responsibility of the patient to change their behaviour.
Advice — giving explicit advice to the patient about why they should stop/reduce their use of the substance.
Menu of strategies to stop/reduce risk behaviour, including setting targets, recognising high risk situations, planning ahead, and giving self-help information. It is helpful to have cannabis information leaflets available, or suggest web-based information sites such as http://www.talktofrank.com.
Empathy.
Self-efficacy: encouraging the patient to use their own resources to bring about change, being optimistic about their ability. Keeping a diary of use (including where, when, and with whom) can be useful in identifying patterns.
- © British Journal of General Practice, 2009.