A 2015 study by Angus Deaton and Anne Case found that income inequality could be a driving factor in a marked increase in deaths among white males between the ages of 45 to 54 in the period 1999 to 2013. So-called "deaths of despair", including suicide and drug/alcohol related deaths, which have been pushing down life expectancy since 2014, reached record levels in 2017. Some researchers assert that income inequality, a shrinking middle class and stagnant wages have been significant factors in this development.