As in all medical disciplines, diagnosis in clinical psychiatry should be reached in a step-wise approach: after assessing the chief complaint of the patient, a careful examination of the psychopathology follows e.g. by using the AMDP system [1Guy W., Ban TA (Eds.) The AMDP-System  New York: Springer, Berlin Heidelberg (1982). 

Cliquez ici pour aller à la section Références] to preliminarily conclude the process with a syndromal classification [2Hippius H. Psychiatrie  Geriatrie/Psychiatrie. Taschenbücher Allgemeinmedizin New York: Springer, Berlin Heidelberg (1979). 67-138

Cliquez ici pour aller à la section Références]. This syndromal classification is of great importance as it guides the initiation of therapy in daily life practice. After gaining additional information (e.g. investigation in the course of the disease, brain imaging, thorough assessment of cognitive function, exclusion of organic causes) a final diagnosis is possible. Unfortunately, a premature jumping to diagnosis is not uncommon (with the potential consequence of incorrect therapies).

In addition to these difficulties, recent neurobiological research has shown that nosologic assignments through conventional diagnostic classifications are far less specific than assumed, revealing a large overlap between diagnostic categories [3Cross-Disorder Group of the Psychiatric Genomics Consortium Genetic relationship between five psychiatric disorders estimated from genome-wide SNPs Nature genetics 45.9 2013 ; 984-999

Cliquez ici pour aller à la section Références, 4The Network and Pathway Analysis Subgroup of the Psychiatric Genomics Consortium Psychiatric genome-wide association study analyses implicate neuronal, immune and histone pathways Nature neuroscience 18.2 2015 ; 199-209

Cliquez ici pour aller à la section Références], e.g. between Schizophrenia and affective disorders. Consequences of this finding are discussed both for the construction of future classification systems and for therapy.