What meth can do to the brains of addicts

The long-term effects on the brain after taking meth are still not completely understood, despite decades of study.

What is known, is that longterm use leads to considerable changes in brain structure and function, with flow-on effects into other aspects of life.

Associate professor of University of Otago’s school of pharmacy Dr Bruce Russell said that while the high from taking meth never completely went away, it decreased over time, to the point that ‘‘most people continue to take the drug to alleviate the symptoms of withdrawal, and getting high is just a bonus’’.

‘‘If people use meth and they become addicted to it, it’s very hard to walk away from.

‘‘If you take another drug, like cigarettes, over 95 per cent of people who try to quit smoking fail within a year. When you have a more addictive substance like meth, it’s even harder,’’ he said.

The addictive aspect of methamphetamine is its chemical similarity to a natural chemical produced by the brain called dopamine.

This chemical is a key component in any stimulus that makes people feel good, and the chemical structure of meth leads to excessive amounts of dopamine in the brain.

This similarity also underlies the reputation of people becoming aggressive while on meth: an overabundance of dopamine is one of the underlying causes of the psy- way, if they were addicted themselves or through family or friends.

‘‘Nobody who starts using methamphetamine is thinking ‘gee I hope I become addicted’. Most people think that they won’t, but one in six people will become addicted and the question is: is it you?’’

Addiction is listed as a brain disease by the American Psychiatric Association (APA), with symptoms including ‘‘distorted thinking, behaviour and body functions’’.

The APA also quoted brainimaging studies finding long-term drug-use leads to ‘‘changes in the areas of the brain that relate to judgment, decision making, learning, memory and behaviour control’’.

Schenk said addiction was not yet well-understood enough to have effective medical treatment, though she was ‘‘optimistic’’ about developing treatment in the future.

Schenk said use of meth changed the brain ‘‘markedly in a lot of different systems’’.

‘‘Part of the reason we don’t have an effective treatment is because we don’t completely understand how the brain has changed,’’ she said. But even the incomplete understanding so far paints a fairly bleak picture.

‘‘Addiction is a brain disease brought on by the use of substances ... and it renders certain systems in the brain entirely dysfunctional,’’ Schenk said.

The dysfunction is at least twopronged: firstly, the homeostasis, or balance, of the brain and body adjusts to the presence of the drug, and creates a ‘‘driving force’’ to obtain more of the drug.

‘‘The whole homeostatic system has shifted, so now the drug has to be on board just to feel normal.

‘‘People are not experiencing that same euphoria that they felt when they first took the drug, it now has become an issue of maintaining the drug and maintaining normalcy,’’ Schenk said.

On top of this, ‘‘the systems [in the brain] that allow you to say ‘no’, so the ones that give you that kind of control about what you do and what you don’t do, those become completely dysfunctional.’’

Not everyone will become addicted, but regardless of the substance, about 15 per cent of recreational users will become addicted, Schenk said.

‘‘It’s a process. It doesn’t happen immediately, it happens to some people faster than others, and it won’t happen at all if you never take the drug, even if you’re predisposed to it.’’

For those fifteen per cent of users who become addicted, ‘‘normal positive effects that you get from eating really good food or having good sex or jumping off a bungee jump – all the things that generally make you happy no longer make you happy.’’

The initial euphoria induced by the drug decreases with each use, but addicts feel compelled to take more to achieve the same initial effect.

‘‘Dependency is not about achieving euphoria, because most drug addicts are quite a dysphoric group,’’ Schenk said.

‘‘People who are dependent on or addicted to methamphetamine are not happy people; but they have this compulsion to continue to take the drug because their brain has changed so markedly.’’

Any person who takes methamphetamine is taking a real chance on whether or not they will become addicted.

‘‘This is a dangerous drug, it changes your brain, it changes your behaviour.

‘‘Go bungee jumping.’’