New insights could boost treatment for P addiction

File photo / NZ Herald

A Kiwi researcher's discovery of new ways methamphetamine can alter the brain could help the development of new drug-based therapies for addiction treatment.

In 2009, New Zealand had one of the highest rates of P users in the world, and today, more than 25,000 Kiwis were estimated to still be using the drug.

Now, new research by a Victoria of University of Wellington graduate has provided valuable insights into how the brain's natural reward pathways are strongly stimulated following exposure to methamphetamine.

As part of his PhD in Biomedical Science, Dr Peter Bosch studied thousands of genes and proteins within this "reward system" to identify what was altered following exposure to the highly addictive drug.

Dr Bosch uncovered a number of genes and proteins which previously hadn't been associated with the drug, along with those which had already been linked to it.

He said identifying these previously undescribed genetic and protein changes represented an exciting target for future drug-based therapies in the treatment of addiction, including relapses, which are a major challenge.

"The brain reward system is a group of cells that send signals when we do anything rewarding, such as exercising, eating food or drinking water," he said.

"Drugs of addiction - like amphetamines or cocaine - target the reward system, activating that particular part of the brain."

Dr Bosch said the biggest challenge for researchers was trying to prevent users from relapsing, which occured in 80 to 90 percent of cases for psycho-stimulant addictions.

"There's something going on in terms of how the brain has responded to the drug, that sets the brain up to relapse at another stage in life," he said.

"By identifying the genes that have been altered, we can explore possible reasons for why some people are more vulnerable to drug relapses."

Dr Bosch said that although New Zealand were among the highest users of methamphetamine worldwide, the genetic and cellular modifications induced by the drug were not completely understood.

"There's not a huge amount of research on methamphetamine compared to other drugs of abuse, like cocaine."

In 2009, New Zealand had one of the highest rates of P users in the world, with 2.2 per cent of the adult population using the drug.

Although the rate of pure amphetamine use had halved since then, and the drug's street price was starting to climb, more than 25,000 New Zealanders were still estimated to be using it.

According to the latest Drug Use in New Zealand Survey 2007/2008, published in 2010, one in ten New Zealanders - representing 285,400 people - had used a stimulant, such as meth, cocaine or ecstasy, for recreational purposes at some point in their lifetime.

Men were significantly more likely to have ever used stimulants, and most had tried stimulant drugs for the first time at age 21 years or older.

Methamphetamine use was similar across socio-economic groups, but was slightly more common among middle to upper socio-economic groups.

The most recent New Zealand Arrestee Drug Abuse Monitoring (NZ-ADAM) report, in 2008, which measured drug and alcohol use among people who have recently been apprehended by police, found that 10.5 percent of people arrested tested positive for methamphetamine.

Methamphetamine was the third most common illicit drug detected in arrestees, behind amphetamines (11.1 percent) and cannabis (68.5 percent).

In other recent New Zealand research on the effects of P, a study co-authored by Dr Trecia Wouldes of Auckland University this year found that children whose mothers used P while pregnant found it harder to learn to walk, draw and grasp objects.

The study was part of on-going joint research between New Zealand and US researchers, which tracked the neurodevelopment of 107 children in Auckland whose mothers used methamphetamine during pregnancy.