Prevalance and structure of anxiety-depression in an Australian community sample

Aims: To describe the prevalence and factor structure of anxiety-depression in a community sample and to derive indicators for treatment planning. Method: A sample of 398 members of the electoral roll for the New England region of Australia were recruited at random and completed the Zung Self-Rating Anxiety Scale and the Zung Self-Rating Depression Scale. Results: The prevalence of anxiety-depression was 28.1%, over twice that for either anxiety or depression alone. The anxiety-depression construct comprised four underlying factors: cognitive agitation and depressed mood, pessimism, cardiovascular reactivity, pain and sleep disturbance. There were different patterns of these four factors across anxiety-only, depression-only and combined anxiety-depression, with evidence of a unique symptomatological profile in participants with clinically significant levels of anxiety-depression. Conclusions: Treatment decisions for anxiety and depression need to go beyond consideration of the two disorders separately to include the underlying factor severity of the combined construct of anxiety-depression.