A study of almost 1,000 students attending post-primary schools in Cavan, Monaghan, Louth and Meath has found that more than 20 per cent of respondents had significant levels of depression.
The study revealed that adolescents from single-parent families and those with low levels of physical fitness were more likely to experience depression.
Researchers used confidential self-administered questionnaires to measure symptoms of depression in the adolescents, who were aged between 13 and 17.
Some 31 per cent of females, compared to 9 per cent of males, had a significant level of depressive symptoms. When age, sex and social class were discounted, adolescents from single-parent families were found to be three times more likely to be depressed than those who were living with both parents.
Respondents who reported that they had a low level of fitness were almost twice as likely to have symptoms of depression than those with high fitness levels.
The researchers also measured levels of self-esteem among the students. On average, males had a significantly higher self-esteem score than females; respondents of both sexes with low self-esteem scores were at least 13 times more likely to have depressive symptoms.
Mental health problems in young people are increasing and the number of adolescents taking their own lives is rising. Suicide is the most common cause of death in 15/24-year-old males in the Republic.
Writing in the current issue of the Irish Journal of Medical Science, the authors say: "Depression in adolescents is a strong risk factor associated with depression in adulthood, and proactive efforts should be selectively targeted at adolescents who have been exposed to identifiable risk factors."
Noting that the number of households containing a lone parent with children had increased by 24.5 per cent between 1996 and 2002, the authors, from the department of public health, HSE North-Eastern Area, said: "This increasing rate of marital breakdown in Ireland has serious implications for the mental health of our adolescents. With self-reported depression at a high level among adolescents, and given the strong association between depression and being from a lone-parent family, it is vital that we selectively target those adolescents who are exposed to this risk factor," lead author and research officer Anne O'Farrell told The Irish Times.
Dr Declan Bedford, a specialist in public health with the HSE North-Eastern Area, said: "We need to take a population health approach to improving the mental health of these young people, as many of the factors that influence mental health are outside the health service."