|1.3 Bipolar Disorders: Contemporary Diagnostic Definitions and a Course-Based Typology|
Current diagnostic formulations of mental disorders describe the primary symptoms of each mental disorder without making direct references to the cause of the “illnesses”. There have been several debates on this practice of categorising and “lumping” mental disorders in this respect, primarily from psychologists and psychiatrists who are taking a dimensional or experimental view of these conditions (Bentall, 2006).
Interestingly, the very same discipline of psychiatric researchers investigating the biological and genetic causes of psychiatric disorder who are largely responsible for our current “nosological” standardisation, are now trying to redefine mental disorders given that the original categories do not appear to provide specific enough “phenotypes” for genetic investigations (Duffy and Grof, 2001)
Nevertheless, current clinical and research practice as it is reflected in the World Health Organisation and the American Psychiatric Association in their diagnostic manuals (ICD-10 and DSM-IV) recognise four different episodes that characterise Bipolar Disorder: Mania, Depression, Hypomania, and Mixed episode (Mania + Depression).
In order to meet the criteria for being present, each episode is characterised by a key number of basic symptoms. Additional criteria that refer to the duration, functional impairment and causal factors (aetiology) are laid out in order for a researcher or a clinician to be able to accurately diagnose the presence of an episode or else a syndromal state of Bipolar disorder.
Bentall, R. 2006. Madness explained: Why we must reject the Kraepelinian paradigm and replace it with a  complaint-orientated'approach to understanding mental illness. Medical hypotheses, 66, 220-233.