The two major classifications for mental disorders, ICD-11 and the DSM-5, have recently been updated1,2 but it is not clear that either is suitable for routine use in primary health care (PHC) settings. Mental disorders are described as though they are separate from one another, with clear borders between them, and within these borders are relatively homogeneous. In fact, neither of these is true, since there are unbroken continuums between them, and there is considerable heterogeneity within their borders.3 Both the ICD-11 and the DSM-5 make arbitrary divisions between the various overlapping syndromes of common mental disorders, and when more than one are present, treat them as though they are two quite separate illnesses. But in general medical settings, this type of comorbidity is the rule, not the exception. It is convenient for clinicians to use categorical models, but dimensional models fit the data far better when these are used with large data sets such as in the World Health Organization’s (WHO) first major study in primary care, carried out using a research interview to detect common mental disorders in 14 different countries.4 The model of best fit is a dimensional model with a common general factor on which all symptoms load, and three subsidiary factors dealing with anxious, depressive, and somatic symptoms.5 Major depressive episode and dysthymic disorder also load on the depression factor; and somatisation disorder, hypochondriasis, and neurasthenia also load on the somatic factor. Anxious symptoms only loaded on the general factor; there was very little specific anxious variance on the anxiety factor.
ANXIOUS AND DEPRESSIVE SYMPTOMS
The most common psychological disorders in general medical practice consist of two highly correlated sets of symptoms …