Increasing prevalence of depression from 2000 to 2006

Depression is the leading cause of disability and is projected to become the second highest burden of disease (measured in disability-adjusted life years) by 2020, but only a few studies have examined changes over time in the occurrence of depression. The aim of this study is to provide evidence to the hypothesis that the prevalence of depression is rising in the Danish population. We will do that in a longitudinal design among adult Danes by studying the trends from 2000 to 2006 of major depressive disorder (MDD) as well as the distribution across the whole Major Depression Inventory (MDI) scale. In addition, we will investigate whether the trend in MDD is similar across socioeconomic groups.

A random sample of 4759 Danes in their forties and fifties were followed in a longitudinal study based on postal questionnaires answered in 2000 and 2006.

The prevalence of MDD increased from 2.0% to 4.9% during 2000-06. Also the distribution of the MDI score in its entirety moves higher up the scale, with the 90th percentile changing from 12 in year 2000 to 20 in 2006. The increasing prevalence is in absolute terms more pronounced among women in their forties and in lower socioeconomic positions.

The rising MDI score indicates that MDD as well as mental health generally is of public health concern.