Unskilled people are almost 10 times more likely to be admitted to psychiatric hospitals than employers or managers, new figures show.
The latest annual report on activities in psychiatric hospitals also shows widespread variations for admission rates in different counties.
Reflecting a long-running trend, those in traditionally lower socio-economic groups had much higher admission rates than better-paid workers.
The proportion of unskilled workers admitted to psychiatric hospitals was the highest of all listed categories (328 per 100,000 population), followed by skilled manual workers (186 per 100,000 population). The lowest rates were for employers and managers (55 per 100,000) and own account workers (68 per 100,000).
However, the authors of the report pointed out that caution should be exercised in interpreting the results, given that 43 per cent of occupations were listed as "unknown".
Overall, the Activities of Irish Psychiatric Services 2004 published by the Health Research Board shows there were 22,279 admissions to psychiatric hospitals last year, a decrease of 752 over the previous year.
This is in line with a general decline in admissions over the past 20 years, largely as a result of an increase in community care facilities.
The high rate of involuntary admissions continued last year. Some 11 per cent of all admissions were without a patient's consent. This compares to 9 per cent in Wales and 8 per cent in England.
Depression was the most frequent reason for admissions (27 per cent), followed by schizophrenia (20 per cent), mania (15 per cent) and alcoholic disorders (14 per cent).
Admission rates varied significantly in different counties. There was a seven-fold variation between counties in the first admission rate for alcoholic disorders, a six-fold difference for depressive disorders and a four-fold difference for schizophrenia.
Overall first admission rates were lowest in Co Monaghan (88 per 100,000) and highest in Wexford (302 per 100,000).
Dr Dermot Walsh, principal investigator at the board, said: "These regional trends could be attributed to variations in service provision and differences in clinical practice, but this would need closer investigation."
At least 14 children under the age of 16 were admitted to adult psychiatric units last year. A further 632 teenagers between 16 and 19 were admitted to such units. In dedicated children's centres, there were 62 admissions. Dr Walsh said the small number of such admissions reflected the shortage of appropriate in-patient accommodation for children.