Study reveals brain shrinkage after meth use

Noteable differences have been discovered in the brains of recovering methamphetamine addicts, compared to those of non-users.

A research team based at the not-for-profit Mātai Medical Research Institute in Gisborne used MRI scans to study the brains of 13 people who had used meth for an average of 15 years and had recently stopped using the drug.

A new paper describes numerous differences in the brains of meth users, compared with a control group of healthy people.

Chronic meth use can cause widespread brain damage, impairing memory, emotional regulation and executive function, say the medical imaging experts for the Methamphetamine Recovery Project, Associate Professor Miriam Scadeng, from the University of Auckland Centre for Brain Research, and Mātai Senior Research Fellow Dr Maryam Tayebi.

Lead author of the paper, neuroscience PhD student Ben Bristow, says they found reduced volume of the cortex – the outer layer of grey matter – across six brain regions in meth users.

The longer people had used meth, the more shrinkage was seen across multiple areas of the brain.

Meth users had significantly reduced volume in the front of the brain, which is the decision-making hub.

“That area is called the right superior frontal cortex and it’s also responsible for impulse control and inhibition,” says Bristow.

“Meth is such a powerful drug. The changes it causes in the brain affecting motivation, reward processing and impulse control make it particularly challenging to abstain.”

The study found meth users had less volume in two parts of the brain region responsible for visual processing, which enables us to recognise shapes and objects.

“One interesting finding was the damage was mainly focused on visual regions of the brain – in the occipital cortex.

“We’re very visual animals, so a lot of the back of the brain is taken up by visual processing,” Bristow says.

A cognitive test was used to assess planning and problem-solving skills.

On average, meth users took longer to formulate and carry out actions, had fewer correct answers on their first attempt to solve a problem, and had more attempts to answer questions correctly.

Heart health was also impaired in meth users, who had more thickening of their heart walls than non-users.

Bristow says the differences found in the brains and hearts of meth users could reflect drug-related effects, but some differences could pre-date meth use – potentially shaped by factors such as trauma, neurological conditions, or previous head injuries and illnesses.

“For example, studies have shown ADHD is more common among people with meth addiction.

“ADHD involves dopamine dysfunction, while meth floods the brain with dopamine.

“Just as methadone is used for opioid addiction, stimulant medication is showing promise in helping with both meth withdrawal and ADHD symptoms,” he says.

The paper offers a snapshot of the brains of people who had been taking meth daily or weekly, within 30 days of stopping using the drug.

The next phase of the project, called the Hīkoi programme, is a longer-term study of brain and heart recovery during abstinence, with multifaceted treatment and support provided to participants.

The study will analyse four Magnetic Resonance Imaging (MRI) scans of meth users’ brains over 12 months.

This is expected to reveal more about whether the brains of meth users begin to recover as they abstain from the drug for a year.

“Early results suggest some brain changes may begin to improve within nine months after stopping meth use, though this can differ from person to person,” says Tayebi, who has funding from the Hugh Green Foundation.

The Mātai team aims to boost the chances of people kicking meth addiction by better understanding how the drug affects their brain and heart and what occurs in these organs as they recover. Therapies could then be developed to target those changes, says Scadeng, who is Director of University of Auckland’s Medical Imaging Research Centre.

Bristow says meth damages the brain through processes called “neurotoxic cascades”.

“Basically, the brain gets over-worked and doesn’t get a break.

“There’s a massive release of dopamine, which is not recycled normally.

“Eventually, that dopamine is broken down into harmful molecules.”

Bristow’s interest in researching the impacts of meth on the brain was fuelled by growing up in Gisborne, which has one of the worst rates of P addiction in New Zealand.

“Even as I went through school, I saw people dropping out and becoming tangled up with meth.

“Doing this research fills my cup. You see people come through, and as they abstain, they change.

“When you see them after a year being clean, it’s inspiring, it’s heartwarming.”

The team’s ultimate goal is to build a model that boosts people’s chances of beating meth addiction through a combination of advanced MRI assessment, psychiatric care including stimulant medication, mātauranga Māori, and reconnecting participants with their cultural identity, says Tayebi.

The Hīkoi programme is funded by the Fred Lewis Foundation. Its community arm is led by Māori researcher Wendy Mohi, while neuropsychiatry is led by Dr Gil Newburn, both from the Mātai Institute.