A long term study conducted by the Canadian University of Montreal has evidenced that cannabis use during teenage years can cause brain damage that is long lasting; in some cases irreversible.

The study tracked and tested 3,800 teenage participants over a period of four years, with the youngest being aged 13. It is a well-documented fact that consuming alcohol and drugs during teenage years, whilst the brain is still developing, can cause developmental problems as well the onset of mental health illness.

Alcohol and cannabinoids are known to cause issues with cognitive abilities such as learning, decision making, concentration and memory retention. These alcohol and drug-related side effects impact directly on the academic ability of adolescent school-aged individuals.

Cannabis harmful effects are lasting unlike alcohol

This particular study’s findings strongly indicate that teenagers who use cannabinoids are causing long-term damage to their still-developing brains. Unlike alcohol where the effects are reversed once alcohol consumption has been stopped.

Teenagers from 31 different Canadian schools took part in the study, submitting details of their alcohol and drug taking over a period of 12 months. The participants’ brains were also tested yearly at school using computer-based cognitive tests. The details were submitted once a year for four years to Montreal University.

The collective data found that:

  • Cognitive problems increased as cannabis use increased.
  • There was a greater margin of cognitive errors in the teenagers that used cannabis, both whilst cannabis was being used and after the cannabis use had stopped.
  • Cannabis caused detrimental effects to the teenagers’ ability to reason, their working memory and their ability to control their own behaviour. These problems also continued once cannabis use had been ceased.

With alcohol, unless severely abused, the harmful effects do not remain. This led the study conductors to conclude that cannabis use is more harmful to teenagers than alcohol.

Teenagers should delay using cannabis

Professor Conrod who helped conduct the study, which was then published in the American Journal of Psychiatry, said:

“They (teenagers) should delay their use of cannabis for as long as they can”

She further added: “Their brains are still developing but cannabis is interfering with that”

This shows a sample case of a visual 3-D rendering of a baseline SPECT scan of a longstanding marijuana user compared to a healthy control subject. The marijuana user has multiple perfusion defects with lower perfusion shown as scalloping and gaps in perfusion of the temporal and parietal areas. The daily use of marijuana decreases blood flow to the user’s brain.

More cannabis prevention education is needed in schools

Considering the findings of the study, Professor Conrod highlighted the need for more drug prevention programmes in schools. PCP agrees that prevention through education is the way forward.

Addiction starts with repeated abuse of a certain mind and mood altering substance. Through repeated abuse of alcohol or a drug, the brain’s chemistry alters to firstly adapt then to compulsively seek and take the drug. Whilst cannabis is not proven to be physically addictive as such, our experience of treating addicted individuals proves otherwise.

Teenagers, in particular, are very vulnerable to developing an addiction as their brain is still not fully formed and is undergoing huge chemical changes as it matures into an adult brain. The human brain continues to form and evolve up until the age of 25.

Marijuana is mainly psychologically addictive, but once an individual’s brain becomes “hooked” there is a strong physical attachment element that will cause the onset of unpleasant withdrawal symptoms once the drug is stopped.

Cannabis withdrawal symptoms

If you are a regular cannabis user and want to stop, you may experience some difficulty in stopping cannabis if you have built a tolerance to it through regular use.

Cannabis addiction withdrawal symptoms can last for up to four weeks and include the following :

  • Mood swings
  • Anxiety
  • Difficulty sleeping
  • Sweating
  • Restlessness
  • Dysphoria
  • Cannabis cravings
  • Physical weakness

The severity of cannabis withdrawal symptoms vary from person to person and largely depend on how much cannabis you have been using.

Private cannabis addiction treatment

If you are unable to stop using cannabis and need help to achieve abstinence, then drug rehab provides an ideal solution. PCP treat many individuals suffering from cannabis addiction on a regular basis. We will provide you with a bespoke medical drug detox and rehabilitation programme.

Our cannabis treatment programme is designed to help you stop using cannabis for good. We heal the root causes of addiction with individualised therapy and provide our patients with the tools required to live a cannabis-free life.

For more information on our affordable cannabis rehabs, please complete our online self-assessment form or contact us directly to book a rehab admission.

Sources and references:




Addiction? Rehab today!