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Large number of New Zealanders unclear on the health effects associated with cannabis use, new reports says

Ahead of next year’s cannabis referendum, a new report has highlighted the many unknowns New Zealanders face ahead of making an informed decision regarding cannabis use.

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Professor Giles Newton-Howes says children, pregnant women and those with mental health issues are most affected. Source: Breakfast

The report out today by the Royal Society Te Apārangi outlines the health impacts of cannabis, the benefits, harms and unknowns.

The referendum will take place at the 2020 General Election and voters will be asked: "Do you support the proposed Cannabis Legalisation and Control Bill?" Voters will have to give a yes or no answer.

An expert who contributed to the report, Professor Giles Newton-Howes says there are a host of unknowns around the impact of cannabis use.

“I think there is a lot to learn,” he says.

“We know a little bit about some things and not much about an awful lot of things, and so as a doctor that’s difficult when we are thinking about cannabis as a medicine,” he told TVNZ1’s Breakfast.

Professor Newton-Howes who works in the Department of Psychological Medicine at the University of Otago says there is reasonable and high-quality evidence that cannabis-based medicines are useful in two types of rare childhood epilepsies, as well as spasticity and muscle problems associated with multiple sclerosis.

Question to be asked in 2020 cannabis legalisation referendum revealed

He says there might be value in other areas such as nausea and vomiting in HIV and chronic pain conditions.

“But the evidence in these areas is much, much weaker and so it makes it much more difficult to know how do we translate that evidence and apply it to New Zealanders.”

He says because cannabis has been a banned substance for so long, it has been very difficult to research its effects.

Those at most risk from the effects of cannabis he says are people under the age of 25, pregnant women and those with mental health issues.

He says in those under the age of 25, clearly cannabis appears to change the way the brain develops and in pregnant women, cannabis crosses the placenta and will affect unborn babies.

“From a mental health perspective, if people under the age of 25 are taking cannabis, we increase the risk of problems like schizophrenia or psychosis,” he says.

“The real difficulty there is they can be very difficult to treat and so although that risk may only be a few people, it could be a massive problem for them and their whānau for a whole lifetime potentially.

“And it may have effects in some more common disorders like anxiety and depression – so there are real risks,” he says.

He says Kiwis need to think hard and be informed ahead of voting on the issue because once a decision has been made, “it’s pretty difficult to unwind it”.