Regular use of cannabis doubles the risk of psychotic symptoms including schizophrenia and is closely associated with anxiety disorders, depression and psychosis, says official advice to the Morrison government triggered by the passage of new laws in the ACT.  The briefing paper prepared for Health Minister Greg Hunt reveals extensive links between cannabis use and adverse mental health affects, which have increased as marijuana is decriminalised.  In the 3 page brief the Health Department lists five “key issues” to consider after the ACT Legislative Assembly passed a private member’s bill allowing adults to possess 50gm of cannabis and grow two plants.

The department notes there has been a sizeable body of work analysing the adverse physio­logical and mental health effects of recreational cannabis use, despite marijuana being decriminalised only in a small number of jurisdictions.  It points to research from the US state of Colorado that found daily or near-daily cannabis use was associated with the development of a psychotic disorder.  The review of medical literature also examined Australian research, which concluded that regular cannabis users doubled their risk of experiencing psychotic symptoms, including schizophrenia, and were at an increased risk of screening positively for psychosis.

“The evidence base regarding adverse health effects linked to cannabis use has broadened considerably since the gradual decriminalisation, and in some cases legalisation, of the substance in certain international jurisdictions,” the department says.  “Adverse health outcomes as a result of regular cannabis use are not limited to mental health and psychotic symptoms.”  The department advised that a 2018 Canadian Medical Association Journal report found an overwhelming volume of evidence outlining the biological harm of cannabis use, including brain changes, adverse cognitive outcomes, negative pregnancy outcomes and testicular cancer.

The briefing also says a psycho­active component in cannabis called tetrahydrocannabinol, the main chemical responsible for the drug’s psychological effects, increased by almost 30% throughout the late 1990s and early 2000s.  This was linked to exacerbated symptoms of anxiety, depression and psychotic symptoms in “naive” users and increased psychotic symptoms and dependence in “experienced” users. In Colorado, the first US state to legalise marijuana, emergency department visits due to cannabis increased slightly while the acute effects of THC, including hallucinations, paranoia and delusional beliefs, markedly increased with higher doses.

Government sources said the departmental advice was a “devastating confirmation” of the health and mental health effects of recreational cannabis and urged ACT Chief Minister Andrew Barr to explain what health advice he received before supporting the legislation.  The federal government also wanted to know whether the territory government was aware of any studies that contradicted the broad global evidence of real and significant mental health effects from cannabis use.  Mr Hunt said he was “deeply concerned about the very real risks cannabis can pose to physical health and, in particular, to mental health”.

“This is why cannabis is a highly regulated drug,” Hunt said.  “Legalising recreational cannabis is dangerous and medically irresponsible.” A spokeswoman said the ACT government consulted experts on the health impacts that might arise from legalising cannabis and stressed that the laws related to personal cultivation and use of cannabis.  “It does not allow for the sale of cannabis or large-scale commercialisation and development as has been seen elsewhere, particularly in the US,” she said.  Therefore, direct comparisons between the ACT legislation and that of other countries should be treated cautiously, she said.

“The government is not anticipating a significant long-term increase in usage of cannabis in the ACT.  “This is based on examining legalisation and decriminalisation internationally where no clear causal link between the legal status of cannabis and usage patterns was observed” the Government spokeswoman said.  Attorney-General Christian Porter is awaiting a copy of the final version of the ACT bill before deciding whether the federal government should override the territory legislation.  He has warned Canberrans that owning any amount of the drug was an offence under commonwealth law.  The ACT law is due to take effect from January 31.

Source: Compiled by APN from media reports

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