One in five teenagers is drinking at least once a week by the time they are in fifth year in school, new research suggests.

“Significant bingeing” was evident at that stage, researchers said and the drinking patterns of boys and girls did not differ significantly, The Irish Independent reports.

And they warned that drinking posed increased mental health risks for teenagers, including emotional and behavioural difficulties.

When they reach the Leaving Cert class of sixth year, 92pc are drinking and one in four is consuming alcohol weekly.

The study – carried out by researchers in UCD and published in ‘Psychiatry Professional’ – followed the drinking habits and mental health of more than 6,000 pupils aged 12 to 19 in 72 secondary schools.

It emerged that 11pc of the teenagers had symptoms of mild depression and a similar percentage had moderate depression.

However, 4pc suffered severe depression, while for another four per cent it was classed as very severe.

The study showed that as the young person progressed through school they became more likely to start taking a drink and that bingeing became more of a problem as they got older.

While 83pc of first-years did not drink, this dropped to 68pc the following year. By sixth year just eight per cent were teetotal.

In the Leaving Cert class of sixth year, one in four was drinking weekly.

A binge for teenagers involved six or more drinks during one session. Nearly two in three first-years said they never binged, but by sixth year this fell to only one in 10.

One in three students was consuming five to six drinks in fifth year, but one in four were downing seven to nine. For one in eight of the students, a session involved 10 or more drinks.

The authors pointed to a “strong association between types of drinking behaviour and severity of depression”, adding of pupils: “The more they consumed, the greater risk of depression.”

The involvement of parents, schools and the wider community, was essential in tackling the problem, the authors said.

“International research suggests that key components of interventions include school strategies focusing on strengthening personal and social-protective factors; family approaches, such as increasing family cohesion; and community strategies – for example, the reduction of alcohol availability through regulation.”