Mental disorders express themselves in a variety of symptoms. Since its inception, psychiatry has tried to create order in these signs of illness. Over time, it has developed a system for making a diagnosis based on symptoms.
Diagnoses serve to facilitate communication among experts. They also form the basis for selecting appropriate therapies. And last but not least, they are necessary for health insurance companies and social security providers to cover the costs.
But psychiatric diagnoses are historically changeable constructs: some have disappeared, others have changed their name, and new ones are emerging. Certain illnesses that were initially classified as psychiatric illnesses are now defined differently.
From the perspective of the people affected, diagnoses can have a stigmatising effect. Others find it relieving when an unknown ailment is given a name.