ONE in five teenagers is drinking weekly by the time they are in fifth year in school, according to a new study.
The researchers said "significant bingeing" was evident at that stage and that there was little difference between boys and girls in their drinking patterns.
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.
They warned that teenagers who drink are at increased risk of developing mental-health problems, including emotional and behavioural difficulties.
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 4pc 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 8pc 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."
Commenting on the findings, the authors said: "Tackling underage drinking in Ireland requires a multi-faceted approach, with the involvement of parents, schools and the wider community.
"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."
Dr Claire Hayes, clinical director of the depression-support charity Aware said: "This is a brilliant opportunity for people to benefit from an established approach to dealing with difficulties which we may all face in life.
"One-to-one cognitive behavioural therapy (CBT) sessions can cost more than €80 each and there are waiting lists of up to one year in many areas.
"It is really good news that Aware is able to provide this free group programme using principles of CBT, and independent research found that many people who complete the Life Skills programme said that it had had a very positive impact on their life."
She added: "We hope that people across the country will take this opportunity to make positive changes in their life."
The online application is available at www.aware.ie.
Topics covered in the programme include recognising and controlling unhelpful thought patterns, building self-esteem and identifying behaviours in life that can lead to difficulties.