Testing the diagnostic expansion hypothesis with a population-based survey of attitudes to depression in Australia.

Introduction: There is growing concern about the increasing use of psychiatric terminology to describe behaviours and experiences that do not meet criteria for diagnosis of a mental illness. We aimed to conduct a nationally representative online cross-sectional survey exploring diagnostic labelling of vignettes describing a person with different levels of depression symptoms or risk and whether this was associated with mental health-related intended actions and psychological distress.

Methods: Australian respondents (n=6142) were randomly assigned to read one of five vignettes describing a person in the following situations: (1) currently well (family history of depression), (2) currently well (own history of depression), (3) subthreshold depressive symptoms, (4) major depressive disorder (MDD) and (5) MDD with suicidal thoughts. They were asked what, if anything, was wrong with this person. Further questions covered intentions to seek professional help or take self-help actions; psychological distress and personal experience of depression.

Results: Labelling non-clinical or subthreshold vignettes with diagnostic labels was relatively common, with a depression label applied by 19.8% [99% CI 16.6, 23.6], 31.3% [99% CI 27.4, 35.6], 47.7% [99% CI 43.4, 52.0], 68.6 [99% CI 64.5, 72.5] and 77.2 [99% CI 73.1, 80.7] of respondents to vignettes 1 to 5 respectively. Younger people were more likely to give a depression label. Across all vignettes, labelling was associated with a greater likelihood of intentions to speak to a health professional or take medication but not with psychological distress or reductions in effective self-help.

Conclusions: Findings suggest that public messages should have a more nuanced approach, making it clear that, for some mental health difficulties, non-medical solutions may be more appropriate, while also taking care not to increase the proportion of people with more severe problems who meet diagnostic criteria but do not seek help.