Reducing the legal age for buying alcohol in fact increases the physical assault in young men - a research by the University of Otago, New Zealand, suggests.

The team explained that when the alcohol buying age was reduced to 18 years in December 1999, the incidents of assaults in young males between the age of 15-19 years increased.

"Our previous research and three other studies showed deleterious effects of the 1999 law change on traffic injury and this was consistent with studies of similar law changes in Australia, the USA, and Canada. There had been no such studies of the effects on assault which is an increasingly important problem in New Zealand and other countries that have liberalized access to alcohol among young people," lead author Professor Kypros Kypri said in a press release.

For the study, researchers examined medical data gathered from hospitals across New Zealand. They concentrated on the number of patients admitted for assault injuries, especially during weekends. The data included assaults record of four years before the change in the legal alcohol buying age and up to 12 years after the law was put into effect. Researchers compared the assault rates in three age groups, which were between 15-17 years, 18-19 years and 20-21 years.

The analysis showed that the assault rates increased for the age groups between 15 to 19 years. More specifically, when the researchers compared assault rates between the age groups of 15-17 and 20-21, they found that after the changed buying age, the number of assaults increased by 25 percent in the younger age group. When they compared the rates in 18 to 19-year-olds to the rates in 20 to 21-year-olds, the team found that the younger group's rate increased by 20 percent.

"Increasing the minimum alcohol purchasing age should be considered as a countermeasure for the rising incidence of assault in many middle and high income countries, including New Zealand," Professor Kypri said

The study, 'Effects of lowering the minimum alcohol purchasing age on weekend assaults resulting in hospitalization in New Zealand,' was published in the American Journal of Public Health.