Derived from the European tradition in psychiatry, this approach argues that certain diagnoses should not be made (those lower on the hierarchy) if other diagnoses are present (those higher on the hierarchy). In this perspective, mood disorders sit at the top of the diagnostic hierarchy. Thus, if a patient has a psychotic symptom, such as hearing voices, then a psychotic disorder like schizophrenia should not be diagnosed unless mood disorders are first ruled out (e.g., the patient is not hearing voices due to psychotic unipolar depression). Similarly, if a patient appears to have borderline personality disorder, this condition should not be diagnosed unless either mood disorders are shown to be absent, or, alternatively, if the patient with a mood disorder is currently euthymic (not in an active mood episode). The same issue holds with attention deficit hyperactivity disorder (ADHD). It should not be diagnosed in the presence of active mood disorder.
In other words, mood disorders can produce, in addition to their own mood symptoms, almost any other psychiatric symptoms; thus, mood disorders are the conditions that are most likely to be missed when other symptoms are present.
The assessment of a possible diagnosis of mood disorders is important, therefore, not only in those persons with mood symptoms, but in persons with any psychiatric symptoms of any kind.
The diagnostic hierarchy of psychiatric disorders
Diagnoses should be made top down; thus, in general, disorders lower on the hierarchy should not be made in the active presence of disorders higher in the hierarchy.