Trends in the relationship between psychological distress and depression diagnosis in the general adult population 2011-2022

Background: Various explanations have been proposed for increasing trends in diagnosed depression in the UK, including increases in the proportion of the population that experience symptoms, changes in the threshold for seeking treatment and changes in clinical recognition or coding practices. Identifying trends over time for the relationship between the experiences of psychological distress and receiving a diagnosis can help explain wider trends in the incidence of clinical depression, such as whether the threshold for seeking treatment and receiving a diagnosis of depression has changed. Aims: This study aims to examine trends in the incidence of diagnosed depression, and relationships between psychological distress and recent depression diagnosis among UK adults between 2011 and 2022. We also assess whether the difference in psychological distress between adults with and without a recent depression diagnosis has changed over time and examine these relationships across subgroups (sex, ethnicity, age, cohort, education and financial stress). Methods: Data were from 66,360 adults (341,764 observations) aged 16 or older from the UK Household Longitudinal Study (UKHLS) across nine fieldwork periods spanning 2011-2022. Psychological distress was reported with the GHQ-12 used as a continuous variable and as a binary variable indicating caseness. Recent depression diagnoses were self-reported. Analyses we run for the overall population and stratified by different sociodemographic characteristics. Results: Incidence of diagnosed depression has not increased over time in the overall sample, but there was a notable increase in some sub-groups, most clearly seen for women aged 16 to 24. There has been a clear increase in the number of cases of psychological distress, but who have not received a recent diagnosis of depression. The level of psychological distress experienced by adults recently diagnosed with depression has slightly increased over time, whilst the difference in psychological distress experienced by adults with and without a recent depression diagnosis remained stable. Subgroup analyses show differences in the distress experienced by those with and without a recent diagnosis based on sex, age, cohort, ethnicity, education and financial situation: temporal trends were mostly similar across groups. Conclusions: Stable trends in (a) the distress experienced by adults recently diagnosed with depression, and (b) the difference in psychological distress experienced by adults with a recent depression diagnosis compared to adults without suggests little support for the hypothesis that depression is being diagnosed at lower levels of psychological distress. Instead, our findings suggest there may be a growing population who are not receiving clinical support for high levels of distress.