The number of young Australians choosing not to drink has increased by more than 50 per cent since 2013.

The International Alliance for Responsible Drinking (IARD) has analysed data from 63 countries trying to understand whether underage drinking is going up or down globally.

It reports that it has declined in more than two thirds of the nations studied. Britain has seen a 46 per cent drop in consumption while 20 per cent of New Zealand 15-17-year-olds are also drinking less.

However among the most significant findings is a 55 per cent increase in Australian under-18s who are opting out of drinking altogether.

But according to Dr Michael Livingston from La Trobe University's Centre for Alcohol Policy research, people around the world are looking at the findings and "scratching their heads".

"It's not just something that's happening in Australia, there are similar trends in around the high income world ... so immediately that rules out anything particular that we've done here," he said.

Researchers have an abundance of theories but none are backed up conclusively by data, Dr Livingston says.

Some studies from Europe and Australia point to changes in parenting with carers less likely to supply alcohol to kids, more concerned about drinking among teenagers and more aware of the potential harms of drinking.

While other substances may be an option for some, it might not necessarily explain why the young are abstaining from alcohol either.

According to an Australian Institute of Health and Welfare study, the proportion of those aged 12-24 who have experimented with illicit drugs also dropped between 2001 and 2016.

Those aged 18-24 recorded the biggest fall of almost nine per cent.

There's also various conjecture about the impact social media has had on underage drinkers.

"There are more risks of being out of control when you're 15 because your photo can be put up on Facebook and Snapchat," Dr Livingston said.

According to a 2018 World Health Organisation report, since 2000 the percentage of people who drink around the world has decreased by almost five per cent.

There is a "reshaping of the market" going on, Dr Livingston says. Some lower income countries like China and India who don't have a long-standing drinking culture are experiencing a rise in alcohol consumption.

"If you're an industry, that's where you want to be selling your product," he said.

The IARD is a not-for-profit organisation dedicated to reducing alcoholism and concerned by the association between underaged drinking, impaired brain development, increased mental health problems and increased risk of alcohol dependence in later life.