Cannabis and young people

Studies have shown that if a young person uses cannabis early in life (before the age of 16 years) and for a prolonged period of time, it can lead to a number of significant problems.

While prevalence rates have markedly reduced over the past decade, cannabis is still widely used by young people, and the possible impacts on adolescent development remains an important issue.

How many young people use cannabis?

Cannabis is the illicit drug most likely to be used by young people. The 2011 Australian School Students Alcohol and Drug Survey found that 14.8% of Australian secondary school students aged between 12-17 years had used cannabis at some stage in their life. The use of cannabis increased with age, with 3.4% of 12 year olds reporting ever having used cannabis compared to 29.2% of 17 year olds.

While the proportion of students using cannabis decreased from 2005 2011 generally, use was still relatively widespread amongst secondary school students, particularly amongst older males. In 2011, more than 1 in 10 older students had used cannabis in the month before the survey and 6.6% had used it in the previous week.

In addition, according to the 2013 National Drug Strategy Household Survey, recent (past year) cannabis use was 17.3% for males compared to 12.0% for females.

What are the concerns about young people using cannabis?

Adolescence is a period when many developmental changes are occurring. It is a time when a young person’s intellectual capacities expand and their friends become increasingly influential.

Adolescent use of cannabis has been linked to a range of developmental and social problems. While there are serious concerns about the potential effects of cannabis use on memory and learning, it is unclear whether the use of cannabis causes lasting problems in this area.

A review of current literature suggests that the early initiation of cannabis use can have an impact on the following:

Memory, attention and learning

Early and continued use of cannabis can:

  • affect memory, attention and ability to think clearly, making it difficult to concentrate and learn new things
  • affect movement and balance whilst intoxicated
  • be associated with a moderate decrease in IQ in heavy, current cannabis users

These effects do not appear to continue once the person has stopped using cannabis.

Poorer school performance

While it is difficult to distinguish whether this is due to learning difficulties, lack of motivation or because cannabis users mix with peers who may be involved in a range of risk-taking behaviours, using cannabis at an early age is independently associated with:

  • poorer school performance
  • increased absent days
  • increasing the risk of leaving school without any qualifications

Problematic behaviours

Studies have shown that those who use cannabis from an early age are at risk of later developing problems, characterised by hardships, social disadvantage, behavioural difficulties and problematic peer affiliations. Using cannabis at an early age is also linked to higher risk-taking behaviour such as:

  • higher levels of leaving the family home early
  • immature sexual activity, which can result in unplanned pregnancy
  • higher levels of offending behaviour such as motor vehicle theft and break and enter offences to pay for their drug use

Increased risk of mental health issues

Cannabis use has been linked to a range of mental health problems such as psychosis, depression and anxiety. The potential for depression and anxiety is increased because cannabis use from an early age is associated with learning difficulties, poorer educational outcomes and problematic behaviour. Using cannabis from an early age places the person at risk of:

  • impaired emotional development
  • increased risk of becoming more dissatisfied with their life
  • increased likelihood of experiencing depression

Other concerns about early use of cannabis by young people

  • cannabis is illegal in Australia as it is in most countries around the world. It is an offence to cultivate, possess, use, sell or supply cannabis. Doing so could result in a caution, a criminal record or even imprisonment, depending on the type of offence and which state or territory it was committed in
  • cannabis can have short- and long-term consequences on health (see factsheet ‘what is cannabis?’)
  • cannabis use can increase the risk of psychotic episodes occurring or trigger a mental illness (see factsheet ‘cannabis and mental health’)
  • cannabis use can lead to dependence in young people who use cannabis regularly over a period of time (see factsheet ‘cannabis and dependance’)
  • relationships with family and other friends who don’t use cannabis may become problematic
  • using cannabis has been associated with a decrease in motivation (although the evidence is inconclusive if an amotivational syndrome actually exists), which can impact on school, work, family, friends and life in general (see factsheet ‘cannabis and motivation’)
  • the cost of using cannabis can result in financial difficulties

For more information please see the web page for ‘young people’ on the NCPIC website.

Factsheet published July 1, 2008. Updated August 2015.