Researcher Dr Chris Wilkins said the trend was no surprise because the Kiwi drug market had always operated mainly among friends rather than through big dealers.
"It's a bit like selling Avon versus through Farmers," he said. "If you have Avon you have people selling on to other people, and that is what has made the illegal drug market so resilient - you take out one person and they might only have three customers."
Massey's annual survey interviews drug users found by word of mouth and through help agencies in Auckland, Wellington and Christchurch.
The most dramatic recent change has been the sudden appearance of new synthetic cannabis drugs - and an equally dramatic reversal in the latest survey for 2012 after Kronic and related products were banned in August 2011 and harmful side-effects became better known.
The effect was most dramatic for Ecstasy users, who are mainly university students.
None of them used synthetic cannabis up to 2009, then suddenly 21 per cent used it in 2010 and 45 per cent in 2011, but the number dropped in the latest survey to 24 per cent.
Read the full report here:
The number of Ecstasy users who smoked natural cannabis dropped from 89 per cent in 2010 to 84 per cent in 2011, but rose again to 90 per cent in 2012 as people were scared off the synthetic products.
Dr Wilkins said he saw the same pattern for BZP party pills after they were banned in April 2008, plunging from 46 per cent of Ecstasy users in 2007 to 25 per cent in 2008 and 15 per cent in 2009. They were down to 9 per cent in 2012.
"There might be a high point of the market of people who wouldn't otherwise use illegal drugs. They are attracted to the legal part of it," he said.
"So when you do make a former 'legal high' illegal, those people are not interested, because as a group they are quite conventional and law-abiding."
The survey found no significant change in the availability of methamphetamine since 2006 apart from a downward trend in Christchurch.
Police "P-lab" discoveries have dropped from a peak of 211 in 2006 to 94 in 2012, suggesting a probable decline in P use.
However, the latest two surveys have found an increase in the number of users of the imported crystalline form of the drug, known as "Ice".
Drug trends
• Dealers take to texting and Facebook.
• Synthetic cannabis use leaps, then falls.
• Local P manufacturing declines.
• Imported 'Ice' rises again.
On the web
www.shore.ac.nz/projects/idms-study.htm.
