The link between the use of cannabis and mental health problems is an issue that receives a great deal of attention in the research and general media. Although severe illnesses such as schizophrenia have received a large portion of this attention, there is also debate about whether the use of cannabis can lead to more common psychiatric disorders such as depression and anxiety.
There have been a number of studies that have explored the link between cannabis use and mental health symptoms. Strong associations are often found but this is not the same as a causal link (i.e. one causes the other).
Does smoking cannabis cause schizophrenia?
Psychosis refers to a number of mental illnesses where people experience difficulty in telling what is real and what is not. Someone suffering from a psychosis might hear voices that are not really there (hallucinations), or believe things that are not true (delusions). Schizophrenia is a form of psychosis.
Hallucinations and delusions can also be accompanied by muddled thinking and speech, making it difficult for other people to understand the person.
There have been reports of people experiencing these psychotic symptoms after smoking a lot of cannabis or more cannabis than they are used to. This is rare and the symptoms, although frightening at the time, usually go away if use of cannabis is stopped. Cannabis has been shown to make psychotic symptoms worse in those who already have a psychotic disorder such as schizophrenia.
Some claim that cannabis can cause schizophrenia. Evidence suggests that cannabis may somehow trigger schizophrenia in those who are already at risk of developing the disorder. Those with a vulnerability to develop schizophrenia, such as having a family history of the illness, should be strongly advised against using cannabis for this reason.
Does smoking cannabis cause depression or anxiety?
The link between cannabis and other more common mental health disorders such as depression and anxiety is confusing, because often cannabis is used to relieve symptoms of depression and anxiety.
Cannabis may seem to help ease depression before the effects of the drug wear off; however after that, smoking cannabis may make depression worse. Those who use cannabis have been shown to have higher levels of depression and depressive symptoms than those who do not use cannabis. Although results are mixed, there is a substantial amount of evidence to suggest that cannabis use, particularly frequent or heavy use, predicts depression later in life. Young women appear to be more likely to experience this effect.
Cannabis can lead to symptoms of anxiety, such as panic, in the short-term, but there is a lack of evidence pointing to cannabis as an important risk factor for chronic anxiety disorders.
Are some people more at risk than others?
Generally speaking, those who start smoking cannabis earlier (early adolescence) and smoke heavily are more likely to experience negative consequences. This may in turn lead to mental health problems, but also lead to more general life problems, like conflict at home or school / work, financial problems and memory problems.
Again, if someone has a genetic vulnerability or has an existing mental health issues, cannabis should be avoided.
What help is available?
Drug and alcohol services and mental health services are available in most areas of Australia and ideally, a coordinated approach that will tackle both issues at the sample time can be arranged. Often medication is available to assist with symptoms and this can be managed by a skilled general practitioner. Additionally there are some psychologists and social workers who may have specific training in this area.
