ABSTRACT
This chapter is devoted to ‘Diagnosing Mental Illness’. The chapter starts with an anonymised clinical case history focused on the diagnostic process, before exploring the purpose of diagnosis in psychiatry, the merits and demerits of diagnosis, and appropriate use of diagnostic systems. This discussion includes considerations of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) (Text Revision), the World Health Organization's ICD-11: International Classification of Diseases (Eleventh Revision), and general approaches to diagnosis in practice. The emphasis in this chapter is on skilful use of diagnosis as a tool for shared understanding and research, rather than dogmatic approaches to symptom-based syndromes in individual cases. Despite the limited role of biological tests in diagnosis in psychiatry, diagnosis remains essential in order to create a common language to talk about psychiatric conditions and human suffering; perform research into new treatments; hopefully identify the causes of mental illness, and protect human rights. Used wisely, diagnosis helps.
