Cannabis Use and Abuse

Synonyms (Street names): Marijuana, hashish, ganja, weed, dope, pot, grass.

• Cannabis is from the flowering plant Cannabis and is made from the subspecies Cannabis sativa L.
• Cannabis is a drug that produces euphoria and reduces anxiety.
• It can cause dependence but addiction as shown by increasing use and inability to discontinue use is uncommon.
• The drug can be used occasionally without causing significant social or mental problems. Withdrawal may cause anxiety and disturbed sleep in heavy users.

• Cannabis can be smoked or ingested e.g. herbal tea, butterpaste.
• When cannabis is ingested it results in cannabinoids which results in its psychological and physical affects.
• The most active of these is tetrahydrocannabinol (THC).

• It is estimated that 4% of the worlds population use cannabis - with rates of up to 10-30% in Europe.
• The number of cannabis smokers is on the increase.
• In 2002-2003, of 11% of the British population reported use in the previous year - this was highest in the youngest age group (16-24 year olds).
• Estimated that 3.2 million people in Britain smoke cannabis.

• Cannabis induces a relaxed state characterised by a series of disconnected thoughts.
• There may also be:
  Psychological affects
  • Relaxation
  • Euphoria
  • Alteration in perception of time, colour and space
  • Short term memory loss
  • Irritability
  Physical affects
  • Dry mouth
  • Dry eyes
  • Bloodshot eyes
  • Increased heart rate
• Effects are prolonged for 2-3 hours after smoking with no clear evidence of hangover or lasting effect
• Ability to drive and operate machinery is impaired due to effects on motor skills and depth perception
• Symptoms of schizophrenia may be worsened

Schizophrenia

• Cannabis use is associated with an increased risk of schizophrenia symptoms not related to a pre-existing psychosis.²
• Early cannabis use (<15 years) brings greater risk for schizophrenia than use by 18 years.
• Risk is specific to cannabis and not other drugs.
• Although most young people use cannabis without problems, a minority has harmful results 1 in 10 cannabis users by age 15 developed schizophreniform disorder by age 26 compared with 3% of rest.

Dependence

• For some years the general feeling was that cannabis does not produce dependence.
• However dependence is common and difficult to treat.³
• Animals exhibit a withdrawal syndrome and a similar problem is being recognised in humans.⁴

Respiratory

Regular high dose users develop episodes of acute bronchitis, wheezing and coughing with changes in pulmonary function. These changes in lung function can be long-term. It is unclear whether these effects are related to the concurrent use of tobacco or cocaine or cannabis directly. Furthermore, tobacco smoking and smoking marijuana is associated with increased respiratory illness amongst other symptoms.⁵

Cognitive function

Some tests have shown a reduction in cognitive function in long-term regular users but this has to be confirmed.⁶

See also Therapeutic Uses of Cannabis.
There have been studies looking at the beneficial effects of cannabis in cancer, AIDS, depression, nausea when using chemotherapy and various neurological diseases e.g. multiple sclerosis.⁷ However, the efficacy is unclear at present and there are concerns regarding its safety.