A groundbreaking study of alcohol-related harm looks into the lived experience of Māori whānau. Video / Whakaata Māori
A new New Zealand-specific study shows that 60% of those using cannabis and alcohol say the former leads to them drinking less.
Māori, men, and young adults aged 21-25 are more likely to be among those whose cannabis use results in less drinking
Cannabis is considered to be, on average, less harmful than alcohol, so the substitution effect could be the basis for practical harm-reduction strategies
Would legalising cannabis lead to an overall reduction in substance-related harm?
This is the “tantalising” prospect teased in a new study into whether cannabis is a substitute or complement for alcohol: 60% of those using both said their cannabis use resulted in drinking less on a“typical occasion”, and also drinking less frequently.
The demographic groups more likely to be among this group include Māori (19% more likely than non-Māori), men (14% more likely), and adults older than 21 (28% more likely for the 21-25 age group, compared to the control group of those aged 35+).
A significant proportion also substituted cannabis for methamphetamine: 40% of co-users said using cannabis led to less meth consumption.
These are the first such New Zealand-specific findings, which could have major implications for how to reduce drug-related harm. Alcohol and methamphetamine topped the list of New Zealand’s most harmful substances in a recent research paper, while cannabis was ninth after tobacco and various opiates.
The speculative teaser is that legalising recreational cannabis might reduce overall drug harm, as people replace more harmful drinking with less harmful cannabis use.
“If cannabis was legal, it wouldn’t stop people drinking. But if they reduced the quantity of alcohol they drank, that would be quite a considerable public health gain,” said Massey University Associate Professor Chris Wilkins, co-author of the paper Exploring the substitution of cannabis for alcohol and other drugs.
“The paper shows the real possibility that there could be an improvement. It’s certainly a tantalising prospect. This could be the most critical factor in any decision to legalise cannabis, because that effect could be massive.
“If it did result in less hazardous drinking, the benefit would completely swamp any of the costs related to legalising cannabis because there’s so many more alcohol users than cannabis.”
An estimated 200,000 New Zealanders use cannabis weekly, with 600,000 who used it in the past year. This is a fraction of the 3.2 million New Zealanders who drank alcohol in the past year, with about 670,000 people thought to be “hazardous drinkers”.
“Even if people didn’t necessarily stop their meth use but they reduced the frequency and amount of meth they use, that could be huge,” Wilkins said.
He’s quick to stress that it’s much more complicated than simply legalising cannabis and then welcoming less overall drug harm.
The paper didn’t measure hazardous drug use, so it sheds no light on how much the substitution effect might reduce the most harmful alcohol or methamphetamine use. Nor does it have any insight into any potential increase in harmful cannabis use, which many US states are now grappling with following legalisation.
The substitution effect is also far from universal. In the 16-20 age group, for example, some said their cannabis use led to less drinking, while for others it led to more.
The study shows 40% of users of both cannabis and methamphetamine said using the former led to them using less of the latter. Photo / Mike Scott
“It’s not a one-size-fits-all solution,” Wilkins said.
“You might say that if we legalise cannabis, we’re going to get less alcohol use. This paper says, ‘that depends’. If I’m an older adult and want to reduce my alcohol use, this could help. But in other groups, it’s going to have the opposite effect.”
Nor is cannabis universally less harmful than alcohol, or methamphetamine. A lot depends on an individual’s genetics, physiology, and circumstances.
“Say I’ve got pre-existing mental health problems, or delinquency in adolescence, then this is not going to help me at all,” Wilkins said.
“It’s quite tricky to realise those benefits, depending on people’s different life stages, different lifestyles, and different ethnicities. It’s hard to legalise cannabis for some people and not for others, or try and control unintended side effects.”
The paper is also about current cannabis users, so it says nothing about how new cannabis users might behave in a new legal recreational market.
A big question mark, then, hovers over whether and to what extent the paper’s findings would play out in a legal recreational market.
A strong substitution effect between cannabis and alcohol has been shown in a New Zealand-specific study. Photo / Hayden Woodward
Complementary vs very different neurological effects
The paper is based on a 2020 online survey of 23,500 people (26,000 minus 2500 following a quality audit) interested in activities associated with drug use, including drinking.
They were asked about their drug use on a typical occasion for substances including cannabis (in joints, grams or cones), alcohol (in standard drinks), tobacco (in cigarettes per day), meth (in points), MDMA (in pills), and LSD (in tabs).
The most prevalent drug used by respondents in the previous six months was alcohol (87% of respondents), followed by cannabis (68%), tobacco (57%), MDMA (45%), LSD (26%), cocaine (12%), methamphetamine (7%), morphine (2%) and synthetic cannabinoids (1%).
Co-users were then asked if their cannabis use meant they used less, the same, or more of each of the other drugs:
60% said they used less alcohol because of their cannabis use;
60% said they used less synthetic cannabinoids;
44% said they used less morphine;
40% said they used less methamphetamine, 53% said their methamphetamine use was the same;
35% said they used less tobacco, though 22% said they used more. This shows cannabis is far more complementary to tobacco than to the other drugs;
A majority said their cannabis use had no impact on their LSD (73%), cocaine (70%) or MDMA (68%) consumption.
Substitution question results for co-users of cannabis and other drugs. Does using the former result in using less, the same, or more of the latter? Source: Exploring the substitution of cannabis for alcohol and other drugs.
“The substitution of legal cannabis for alcohol may reflect the similar neurological effects of each substance, similar social acceptability among young people, and comparable price,” the paper said.
Conversely, different neurological effects could explain the lower substitution effect for MDMA, cocaine or LSD, whose higher prices compared to cannabis could also be a factor.
Cannabis is a depressant that facilitates introspection and relaxation, while LSD typically offers an immersive psychedelic experience, and MDMA enhances energy and empathy.
Methamphetamine also enhances energy, but researchers speculated that its higher substitution effect by cannabis could be because of the latter having “fewer negative side effects and withdrawal impacts”.
Dr Chris Wilkins, a drug policy researcher at Massey University. Photo / Doug Sherring, File
‘Colonisation and exploitation’
Māori were not only more likely to drink less because of their cannabis use, but also to use less tobacco, methamphetamine, MDMA, and LSD.
“This suggests that Māori may be more likely to consider cannabis to be the preferred substitute for many other drug types,” the paper said.
“This may reflect a more positive cultural perception of cannabis among Māori and other colonised indigenous and ethnic groups (eg, Jamaicans) as an anti-establishment drug compared to alcohol and tobacco, which have been historically associated with colonialisation and exploitation.”
Those aged 16 to 20 were overall less likely to have their cannabis use result in lower levels of alcohol, tobacco, methamphetamine, MDMA, and LSD use.
This cohort includes those leaving home for the first time, who are more likely to be in an experimental, novelty-seeking phase. That includes cannabis and alcohol, rather than cannabis or alcohol.
“But the next age cohort – 21 to 25 – was more likely to say using cannabis resulted in less alcohol,” Wilkins said.
“It’s slightly beyond that initial phase of hedonistic partying. They’ve had some bad experiences, and they’re starting to think more holistically about their substance use and saying, ‘If I use cannabis, I won’t drink as much.’”
But the findings of the paper could be useful in other ways, Wilkins said.
“You could try some experiments where you allowed people to get a prescription for medicinal cannabis, if it meant reducing the use of other more harmful drugs like methamphetamine, alcohol, opiates.
“It’s easy to say and probably really difficult to implement. But that would be one way you could try and possibly open it up.”
Several studies have looked into medicinal cannabis and alcohol, with substitution rates ranging from 25% to 51.7%.
“Our study suggests cultural groups with an existing positive cultural affinity for cannabis may be particularly engaged to use cannabis in this role to support lower risk drug use or treatment options,” the paper said.
“Harm-reduction initiatives could include peer and community-run programmes offering free or low-cost cannabis to disadvantaged people experiencing substance use issues, as has been trialled in Vancouver.”
Derek Cheng is a senior journalist who started at the Herald in 2004. He has worked several stints in the Press Gallery team and is a former deputy political editor.
