The relevance of ‘mixed anxiety and depression’ as a diagnostic category in clinical practice

According to ICD-10 criteria, mixed anxiety and depressive disorder (MADD) is characterized by co-occurring, subsyndromal symptoms of anxiety and depression, severe enough to justify a psychiatric diagnosis, but neither of which are clearly predominant. MADD appears to be very common, particularly in primary care, although prevalence estimates vary, often depending on the diagnostic criteria applied. It has been associated with similarly pronounced distress, impairment of daily living skills, and reduced health-related quality of life as fully syndromal depression and anxiety. Although about half of the patients affected remit within a year, non-remitting patients are at a high risk of transition to a fully syndromal psychiatric disorder. The validity and clinical usefulness of MADD as a diagnostic category are under debate. It has not been included in the recently released DSM-5 since the proposed diagnostic criteria turned out to be not sufficiently reliable. Moreover, reviewers have disputed the justification of MADD based on divergent results regarding its prevalence and course, diagnostic stability over time, and nosological inconsistencies between subthreshold and threshold presentations of anxiety and depressive disorders. We review the evidence in favor and against MADD and argue that it should be included into classification systems as a diagnostic category because it may enable patients to gain access to appropriate treatment early. This may help to reduce patients’ distress, prevent exacerbation to a more serious psychiatric disorder, and ultimately reduce the societal costs of this very common condition.