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Drug dependency: cannabis

Information Services

Alcohol and Other Drugs

Drug dependency: cannabis

Cannabis use can worsen the effects of a brain injury and is connected to a wide range of cognitive and emotional issues.

People smoke cannabis for a number of reasons. Some of these include stress relief, coping with difficult feelings, boredom or to gain acceptance within a social circle. The term 'cannabis' is used interchangeably with marijuana, pot and hash.


Using cannabis can become the main way to deal with difficult feelings, which prevents a person from learning new skills to effectively cope with day to day stresses. This can eventually lead to problems with mental health, employment and relationships.

The active chemical in cannabis gives a 'high' feeling although it is technically also a depressant - it slows down the central nervous system causing a relaxed feeling throughout the body. 


General effects include:

  • loss of coordination
  • low blood pressure and faintness
  • blurred vision
  • poor judgement
  • reduced attention
  • changes in mood


Heavy use is associated with:

  • paranoia
  • anxiety
  • confusion
  • poor memory
  • concentration.


The effects of cannabis are associated with a number of risks - the short-term risks include injury due to falls, risks-taking behaviors and car accidents. Long-term risks include lung cancer, increased susceptibility to mental or psychotic illness and problems with employment and relationships.


Cannabis use after a brain injury

After a brain injury a person may become more sensitive to the effects of drugs including cannabis. It is generally recommended that people avoid drug use after a brain injury, including alcohol.


Cannabis can magnify the existing effects of a brain injury including poor memory and attention, impulsivity, poor muscle coordination and speech difficulties.

Long-term use has lasting effects on memory and attention skills on top of damage already sustained through Acquired Brain Injury. These problems worsen the longer cannabis use continues.

Cannabis use can interfere with recovery and participation in community programs following an Acquired Brain Injury.

In a person with a brain injury cannabis use is more likely to produce adverse effects, including decline in memory, attention and confusion.

References and further information

Helpful Contacts

[1] Hall, W., L. Degenhardt, and M. Lynskey, The health and psychological effects of cannabis use. National Drug Strategy Monograph Series. Vol. 44. 2001, Canberra: Commonwealth Department of Health and Ageing.


[3] Australian Institute of Health and Welfare, 2008 National Drug Strategy Household Survey: first results. Drug Statistics Series number 20. Cat. no. PHE 98, AIHW: Canberra.

[4] Australian Institute of Health and Welfare, 2004 National Drug Strategy Household Survey: Detailed findings. AIHW cat. no. PHE 66. 2005, AIHW: Canberra

[5] National Cannabis prevention and information centre 2008 "Population trends in cannabis use and first results of a study on cannabis-related emergency department presentations" (accessed 5 September 2008)



[8] Department of Health and Aging. (2008). Cannabis and Mental Health: Put in Context. National Drug Strategy, Monograph Series no. 68


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