In 2015 Anne Case and Angus Deaton wrote a paper documenting mortality increases among white middle-aged lower socio-economic status people in the United States. The paper attracted a lot of debate both in terms of its political implications and the complexities of the statistical analysis used to calculate the trends (see e.g. Gelman and Auerbach reply, Case and Deaton reply; Noah Smith summary of the debate).
Case and Deaton have recently released another working paper that increases the scope of their original work, including the addition of a wider set of comparison groups, including Ireland. The paper is available at this link. The key table that includes Ireland is below, showing the well-documented declines in mortality during this period, that were partly offset by increases in deaths from drugs, alcohol, and suicide. The late Brendan Walsh had an excellent paper that shows what lies beneath the suicide aspect of most of these trends for Ireland, in particular the competing roles of high but declining rates of alcohol consumption and initially low but then sharply increased rates of unemployment. Richard Layte and others have written about the patterns of mortality during the bulk of this period. The declines in mortality from heart disease among this age group really gives some pause for thought.