The Illegal Drug "Ice" Can Have Severe, Long-term Effects On Users' Brains

THE initial rush, or "flash", has been described as better than sex, a feeling of invincible euphoria.  But the high that methamphetamine hydrochloride - "ice" - provides the Saturday-night user has repercussions on Monday, with a comedown that ranges from sleeplessness and anxiety to lethargy and depression. 

Beaver Hudson, an emergency psychiatry nurse consultant in the emergency department at St Vincent's Hospital in Darlinghurst, is well versed in the effects of ice, having seen more than 500 cases of methamphetamine intoxication in the past two years. 

"We get all types of people turning up," Hudson says. 

At the Australasian Amphetamine Conference in Sydney tomorrow - the first national conference on amphetamine use - Hudson will describe cases that range from agitated patients to a patient who attemptedsurgery on his genitals. 

"He developed an abscess from injecting ice into his penis," Hudson says.  "We almost had to amputate it. 

"Users can move rapidly from oral ingestion to intravenous injecting, to get the same hit."

In some cases the high can bring on a psychotic episode, including hearing voices and hallucinations, lasting from a few hours to days. 

Hudson says the drug can have bizzare and sometimes violent effects on behaviour as a result of decreased inhibition - from patients complaining of shooting pains throughout their body, to patients arriving at the emergency department naked and threatening suicide. 

At St Vincent's there are two rooms for behavioural emergencies - with reinforced walls and beds with no sharp edges - where patients suffering paranoia or psychosis are put until the effects of the drug wear off. 

"About 90 per cent of methamphetamine presentations are handled in the behavioural emergency rooms," Hudson says. 

Varieties of methamphetamine range from "speed" or "base", which has purity of about 10 to 20 per cent, to crystal methamphetamine, known as "ice" or "crystal", which is about 80 per cent pure. 

While speed is usually swallowed or snorted, ice is more commonly injected or smoked through a glass pipe, giving the user a much stronger high along with bigger "comedowns" and a greater risk of addiction. 

Professor Iain McGregor, from the psychopharmacology laboratory at the University of Sydney, says while snorting takes about two minutes to take effect on the brain, smoking or injecting takes a matter of seconds. 

Faster absorption of the vapours produced when the drug is smoked, combined with greater purity, produces the "rush."

"Not only is the drug stronger, it also produces an immediate rush which is one of the reasons it is addictive," says McGregor, who will present findings from methamphetamine studies on animals at the conference tomorrow. 

When methamphetamine enters the brain it works to boost levels of the neurotransmitters dopamine, noradrenaline and serotonin. 

These neurotransmitters are natural chemicals that make us feel excited, alert and motivated. 

While other party drugs such as ecstasy work primarily to boost serotonin, methamphetamine works primarily on dopamine, flooding the brain with this chemical and preventing the natural flow of the chemical back into the neuron. 

" High levels of dopamine make the world seem very interesting and exciting," McGregor says. 

"However, if levels are too high then people lose their ability to make sense of the world, resulting in psychosis and bizarre behaviour.  Dopamine is also intimately involved in sexual motivation, and dopamine boosters such as methamphetamine produce sexual overdrive."

As the drug wears off, dopamine production becomes exhausted and the brain experiences a depletion or "comedown". 

"The world seems a lot less interesting, and dull," McGregor says. 

As the brain becomes accustomed to dopamine, users crave bigger doses of methamphetamine to achieve the same high.  "Long-term users develop a motivational toxicity where they can't do anything without the drug."

McGregor says long-term use of methamphetamine can also cause long-term damage to dopamine neurons as well as more general adverse effects on the brain.  Research from the University of California Los Angeles showed long-term methamphetamine users had a reduced volume of brain tissue in the prefrontal cortex, responsible for higher cognitive ability, and in the hippocampus, involved in learning and memory. 

Stimulation of the adrenaline receptors also affects the the central nervous system, causing increased physical activity, wakefulness and heart rate and decreased appetite - symptoms Beaver Hudson sees in his patients any given weekend in Sydney. 

Hudson points out, however, that symptoms are often difficult to attribute to methamphetamine use alone. 

"Nine times out of 10 there are always other drugs involved, they take something to mitigate the agitation they feel," Hudson says.  "The effects can accumulate."