3.3 Understanding diagnosis – key issues
Diagnosis of mental health conditions is commonly based on one or other of two classification schemes. These are (i) the Diagnostic and Statistical Manual of Mental Disorders, currently in its 5th edition (DSM-5 [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] ), published in 2013 by the American Psychiatric Association, and (ii) the World Health Organization’s ‘International Classification of Disease’ or ICD, which has been revised at the time of writing (ICD-11, which became available on 18 June 2018). You can read about DSM and anxiety in a short paper by David Kupfer from the Department of Psychiatry at the University of Pittsburgh School of Medicine, published in 2015 (a link to the article is provided in the References section).
There continues to be considerable controversy and debate around the use of one system over the other in mental health research and clinical practice. The ICD was initiated more than one hundred years ago as a means to help classify disorders in medicine more generally, and it has been argued that this system also ‘allows greater clinical discretion in making a diagnosis’ for mental health conditions (Tyrer, 2014). The DSM was specifically developed for mental and behavioural disorders, and its reliability in test-retest situations has continued to improve through subsequent iterations, particularly since its third edition (DSM-III), which was published in 1980. Nevertheless, there continues to be a split between those who adhere to the DSM versus those whose preference is for ICD, and criticisms have been directed against both systems (Tyrer, 2014).
Added to the above are further complications:
assessment, diagnosis and treatment of psychiatric (behavioural and mental health) conditions have evolved over many decades around the world mainly from research carried out in ‘specialist’ settings such as hospitals and clinics (institutions), as opposed to more ‘natural’ environments such as within the community;
there are differences in approach to diagnosis (e.g. ‘patient-centred’ versus ‘disease-based’); and
symptoms may overlap between diagnostic classifications (comorbidity), or may not meet the criteria for a particular disorder, but still require treatment. Taking these issues as well as the views of patient groups and advocates into consideration, there has been a move over recent years, and particularly within the UK, towards a more integrated (‘individualised’ or ‘tailored’) approach to diagnosis and management of mental health that takes the lead from and involves the patient as a service-user (Gask et al., 2009).
Much of the controversy and ensuing debate around diagnosis has arisen due to the fact that a clinical diagnosis is not always straightforward. Psychiatric diagnoses have historically been based on presenting symptoms, and to this day psychiatric nosology remains almost exclusively based on presenting signs and symptoms and descriptive taxonomy. Taking anxiety and depressive illness as examples, the first thing to note is the overlap in signs and symptoms between these conditions, termed ‘comorbity’. Then there remains a fundamental lack of standardised ‘biological’ parameters (‘disease’ identifiers or ‘biomarkers’) that could arguably represent a more objective measure to support clinical diagnosis. Biological and genetic markers which can be used to screen for conditions such as diabetes, cancer or metabolic diseases, to help identify and delineate a specific ‘disorder’ or a pathophysiological (i.e. ‘disease’) state, continue to remain elusive for most psychiatric conditions.
It was anticipated that psychiatric diagnoses in DSM-5 would include, in addition to signs and symptoms, brain imaging, biomarker and genetic data, and in doing so add some measure of sensitivity and specificity to diagnosis, but this has not been realised (Nemeroff et al., 2013). Diagnosis according to the DSM remains ‘phenomenologically-based’. DSM-5 does, however, have an increased focus on trauma-related and stressor-related disorders, which could lead to increased recognition and understanding of adversities, in particular those that may be experienced during childhood and adolescence. Indeed, one of the biggest shake-ups from the previous edition has been to the classification of anxiety and related disorders. The DSM-5 chapter on anxiety disorder no longer includes obsessive-compulsive disorder, post-traumatic stress disorder, or acute stress disorder.