More high school students are staying away from alcohol, despite - or perhaps because of - growing problems with youth binge drinking.
A new Auckland University analysis of a 2007 survey of 9000 high school students has found non-drinkers rose from 30 per cent in the earlier 2001 survey to 39 per cent.
Students who thought it was "not okay" for people of their age to drink alcohol regularly jumped even more dramatically, from 51 per cent to 65 per cent.
Ironically this could be partly because of growing awareness of what alcohol is doing to their friends.
Among high school students who do drink, the numbers bingeing on at least five standard drinks at a session in the previous month rose from 49 per cent in 2001 to 57 per cent.
The combination of fewer drinkers, but more bingeing within the group who do drink, kept the overall proportion of students bingeing in the previous month stable at around a third.
"There's a greater level of polarisation among young people," said research leader Professor Shanthi Ameratunga.
"There are quite alarming proportions of young people who report various adverse things that happened to them in the previous year that they attribute to alcohol.
"But when we dig below the surface, we find there are actually increasing proportions of young people who don't necessarily approve of high levels of drinking and to some extent delay drinking altogether."
The report found most high school students drank alcohol at least occasionally from age 14. Drinkers increased from 38 per cent of those aged 13 or younger to 54 per cent of 14-year-olds, 66 per cent of 15-year-olds, 74 per cent of 16-year-olds and 76 per cent of those aged 17 and older.
Most of the 14 and under group were given alcohol by their parents. From 15 on, they were more likely to get it from friends.
A tenth of 15-year-olds, 15 per cent of 16-year-olds and 21 per cent of 17-year-olds bought it themselves, even though the legal age is 18.
More than a fifth (22 per cent) of drinkers said they'd been injured after drinking in the past year, 20 per cent had done things such as stealing that could have led to serious trouble, 14 per cent had unprotected sex, and 10 per cent said drinking had affected their schoolwork or part-time jobs.
Eleven per cent of drinkers said they were worried about their own drinking and 12 per cent had tried to cut it back or give it up.
But the proportion of drinkers had dropped by more than 10 per cent since 2001 at all ages up to 15, and by 6 to 8 per cent at older ages. In 2001, 82 per cent of both 16- and 17-year-olds were drinkers, in line with the adult average of 84 per cent, but this fell to 74 and 76 per cent in 2007.
Massey University Professor Sally Casswell said the data matched her own research, which found drinkers aged 14 to 15 and 18 to 19 jumped between 1995 and 2000, after the drinking age was lowered to 18 in 1999, but fell back again in 2004. Drinkers aged 16 to 17 continued to decline through her three surveys.
"There appears to be a polarisation going on, or it could reflect, in part, new immigrants coming in from lower drinking countries," she said.
Immigration boosted numbers of Asian and Pacific students between the 2000 and 2007 Auckland University surveys, and Asians (35 per cent) and Pacific students (43 per cent) are much less likely to drink.
But Professor Ameratunga said that couldn't account for the whole increase in non-drinking.
Maori, who are most likely to be drinkers (73 per cent), were over-represented in the 2001 sample but formed a smaller part in 2007. European students are big drinkers too (66 per cent) and their share of the sample also fell.
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