Spectrums of conditions

Abstract

Psychiatric diagnostic constructs often have no zones of rarity between different diagnostic constructs, and they often co-occur. This happens even where clear disease processes are involved, such as the dementias. They may represent different areas of a spectrum of illness/condition and/or be part of a spectrum of illnesses/conditions. However, they share both these characteristics with many general medical diagnostic constructs. For spectrums of illness/condition this may be because there are no natural boundaries but that it is important or seems obvious to recognize different areas of the spectrum for reasons of clinical utility (such as different prognostic implications or treatments) or different clinical pictures. For spectrums of illnesses/conditions the reason for co-occurrence may be because different diagnostic constructs have similar causes/mechanisms. On the other hand, these problems of lack of boundaries are not present as commonly in general medical diagnostic constructs. Alternative mental health classifications do not have the same issues with co-occurrence. They may be more useful in research to discover reasons why co-occurrence of symptoms may occur but have pragmatic drawbacks for other classification functions.