If one of the major current challenges in the classification and diagnosis of mental disorders is the issue of multi-morbidities, a further one is the subtreshold states. These challenges could be partially considered as the by-products of the prevailing current categorical approaches in our classification systems.

The categorical approach needs and is based on vertical and horizontal boundaries to differentiate different states of human behavior. While, at a horizontal level the boundaries between mental disorders are elicited by strict diagnostic criteria, the issue of drawing a threshold at a vertical level requests some dimensional approaches. These thresholds in the description of many mental disorders in our current categorical approaches are defined by a combination of some dimensions; i.e., the duration of the symptoms, the severity of the symptoms, and the effects of the symptoms on social functioning and abilities.

Another problem in defining the thresholds for mental disorders is the consequence of the cross-sectional approach. Since, the clinical pattern of many mental disorders change in time, the cross-sectional approach does not reply to the requirements of a historical perspective from which the variation of a mental disorder over and under a given cut-off line in due course could be understood. It is a widely shared opinion that the necessity of defining thresholds for mental disorders is not only taking the clinical, scientific and research motives into consideration, but also the forensic and administrative grounds.

This presentation will mainly discuss the phenomenon of threshold and subtreshold states in the context of psychopathology, clinical practice and classification systems.