A new study, drawing on longitudinal data from 1000 Kiwis born in 1977, suggests there may be some predictive risk factors – even in childhood - for people using meth. Photo / Getty Images
Can we predict – or even prevent – those likely to become tomorrow’s meth users?
A new study, drawing on longitudinal data from 1000 Kiwis born in 1977, suggests there may be some predictive risk factors – even in childhood - for people using the dangerous and highly-addictive drug.
And it’s hoped the findings, just published in the journal Addictive Behaviours, will help inform intervention efforts.
In 2020, Otago University researchers published findings indicating that nearly a third of Kiwis now aged in their 40s had tried meth at least once – and that those who’d used the drug at least weekly were between two and five times more likely to be involved in violence.
The latest study – carried out as part of agreement with the NZ Police – traversed similar ground and used the same rich resource: the ongoing, 45-year-old Christchurch Health and Development Study (CHDS).
CHDS director Professor Joe Boden said the study’s now middle-aged cohort members had been quizzed on their use of a range of drugs – including methamphetamine - since they were in their mid-teens.
After analysing links between various individual, social and family factors in the participants’ lives up to the time they turned 16, and any or regular meth use in adolescence and adulthood, the researchers began to home in on some potential predictive factors.
“We started with a long list of things that appeared to be related to meth use, and through statistical analyses we narrowed those down to a much smaller list,” Boden said.
“We also looked at contemporaneous predictors of meth use – or things that were linked to meth use and measured at the same time - including mental health, use of other substances, and life stress and unemployment.”
What stood out?
Perhaps unsurprisingly, a parental history of illicit drug use, having deviant peers and “conduct problems” in middle childhood – like antagonistic and violent behaviour – were among the predictive factors.
But these also included being raised under “maladaptive” or controlling parental behaviour and having a high level of novelty-seeking, along with being male.
“In adulthood, the contemporaneous predictors of meth use included unemployment, life stress, and problems with the use of alcohol, cannabis, and nicotine,” Boden said.
“These findings reflect those of a number of studies, but again those generally did not follow people over the life course, or did not use a general population sample.”
Boden said the research could be used to identify those most at risk of methamphetamine use and regular use – something likely to lead to addiction – if one were to undertake a comprehensive assessment of children who were born to at-risk families.
“We know that young people who exhibit early risk factors such as conduct disorder have a high risk of being poly-substance users at an early age, and our research shows that meth is part of this,” he said.
“Interventions at the individual level with at-risk children could focus on preventing or at least delaying experimentation with substance use.
“Family-level interventions could include programmes aimed at improving parenting, and reducing illicit drug use among those who are parents.”
He added that the findings did come with some caveats: namely that the study cohort happened to have a higher rate of substance abuse than those born into later generations.
There were also some data limitations around those regular meth users.
“While there was a high percentage of people who used methamphetamine – 29 per cent - the percentage of those who used it regularly was much smaller, at six per cent,” he said.
“This is what is usually observed in a population cohort – we see what the ‘average person’ does, so we do not have many cases of people who are high level users.”
In the earlier-published studies, Boden and colleagues found those who used meth at least weekly were more than twice as likely to be the victim of intimate partner victimisation; and almost five times more likely to be the perpetrators of violence.
Harm from the drug had increased in step with global supply networks broadening their reach out of Asia and trafficking in more pure crystalline forms of meth.
“It has long been suggested that amphetamines increase the risk of violence perpetration and victimisation, but evidence thus far has shown only evidence of association, rather than a direct causal link,” Boden said at the time.
There was a need for robust evidence on the link between meth and violence in our New Zealand communities.
The study also suggested meth was the third most common illicit drug in New Zealand, after cannabis and ecstasy.
“Some violence is likely associated with involvement in the drug trade, but our study findings indicate that reducing rates of methamphetamine use in the population overall would result in decreased incidence of violent assaults.”
Meanwhile, another study has suggested living in “healthier” communities could indeed be linked to better mental health for our youth – even when considering the raft of other factors at play.
Academics have been tracking rising rates of youth depression in New Zealand – something one 2020 report dubbed a “silent pandemic of mental morbidity” - with the national Youth19 survey showing only about 69 per cent reporting good emotional wellbeing.
More recently, a major Herald investigation highlighted how the Covid-19 pandemic accelerated rises in anxiety, depression, self-harm, eating disorders and other conditions among children and adolescents, overwhelming the specialist services that treat them.
As the University of Canterbury’s Dr Matt Hobbs explained, mental health conditions often arose during adolescence.
The environment a young person grows up in is associated with their mental health: nationwide geospatial study using the integrated data infrastructurehttps://t.co/oAolZwtQgU
— Dr Matthew Hobbs🏃 (@hobbs_PA) April 14, 2023
“Depression is also one of the leading causes of illness and disability among adolescents, and suicide is the third leading cause of death in adolescents aged 15 to 19 years,” said Hobbs, of the university’s GeoHealth Laboratory.
“Moreover, we know that mental health conditions often begin in young people and persist to adulthood.”
While there happened to be many individual influences – not least a person’s genetics and the home and social environments they grew up within – there were other wider ones that also needed to be considered, he said.
It was even possible that peoples’ very neighbourhoods could be making things worse – but how?
In earlier work, Hobbs and colleagues developed a nationwide geographical measure to assess that factor, based on access to a set of five “health-promoting” features – like green spaces and fruit and vegetables stores – as well as five “health-constraining” elements, like liquor stores and gambling venues.
“We wanted to investigate how our healthy location index was related to mental health in young people,” he said.
“Importantly, researchers often only focus on liquor stores or greenspace, but our measure includes a more holistic picture of a healthy neighbourhood.”
That index was used alongside detailed socio-demographic and mental health information on some 917,000 young Kiwis, captured by a Stats NZ-run repository called the Integrated Data Infrastructure (IDI).
Around 68 per cent of the study cohort were European or “other”, with roughly a quarter Māori, while a similar proportion lived in the most deprived quintile and just over half lived in major urban areas.
There was also a relatively even split between sexes and age groups included, covering those aged 10 to 24 years.
“By using the IDI, we were able to examine a wider range of mental health conditions which included emotional, behavioural, substance problems, and self-harm,” he said.
“Overall, there was evidence of a relationship between the environment a young person resided in and their mental health.”
Young people residing in unhealthier environments had higher likelihoods of any mental health condition and any emotional condition, while those in “health-promoting” environments had lower likelihood of substance problems.
At the same time, they found no significant effects on behavioural conditions.
“The findings provide some support to the hypothesis that the environment a child grows up in,” the study authors concluded, “especially the combined influence of multiple environmental facets, may contribute to their mental health condition”.
Hobbs said that, while the study’s observed effects were small, it underlined a need for policymakers to consider all factors that could influence peoples’ wellbeing – and how these happened to “co-occur”.
“Indeed, previous international and New Zealand research has documented that environmental features often cluster together,” he said.
“For instance, alcohol outlets may collocate in areas where gaming venues or indeed even more health-promoting venues such as physical activity facilities may also locate due to customer demand, land-use patterns or planning regulations.”
The findings also offered some evidence to support recommendations from 2018′s He Ara Oranga: Report of the Government Inquiry into Mental Health and Addiction.
“Overall, policymakers could use the Healthy Location Index and evidence from this paper to help justify a focus on the environmental determinants of mental health,” Hobbs said.
“That includes access to and the quality of our neighbourhoods to create a more holistic vision of what a healthy place or neighbourhood could be, rather than focusing on environmental features in isolation.”
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